1/8th scale Electric Racing!!!

[Combatcm]

Ok I found a mount I'm going to use. Its an associated motor mount. I dremeled out the middle hole so the center diff joint can pass through. I fit it up and bought an E maxx pinion to fit it up, however the pinion doesn't work, is this the reason they have those mod 1 pinions? Anyway judging by the closest and furthest motor placement I can pretty much fit anything I want in there. I just drilled 2 holes in the mount and lined them up with the brake assembly holes, which fit really well, I just need to find where to mount the bottom one. They will all be bolted with nuts.

It's so sweet.

[Combatcm]

Mod 1 pnions are for buggy spurs right? I wouldn't want them to fit like the e-maxx ones.

[starluckrc]

Yes....you need mod 1. If you run a hardened steel spur, you need hardened steel pinions. I have the ones Craps had made, and I believe those are the only somewhat affordable ones around. If it's an Ofna diff with 51 tooth spur, you are better off switching to the plastic spur to run the cheaper stainless pinions.

[Rotary Rocket]

Yes....you need mod 1. If you run a hardened steel spur, you need hardened steel pinions. I have the ones Craps had made, and I believe those are the only somewhat affordable ones around. If it's an Ofna diff with 51 tooth spur, you are better off switching to the plastic spur to run the cheaper stainless pinions.

I did not know OFNA had a plastic spur to directly replace the steel one for the center diff?!

[DualBL]

it depends on the buggy...
On my Hyper7, the spur, is integrated into the diff, and I don't believe you can get a plastic one... I believe the 9.5 has a similar setup.
here's a pic of what I mean by "integrated"
http://www.ofna.com/images/man-hyp7pro-2.jpg

for the MBX R2, the diff can be assembled seperately, and the spur gear is attached later, so I believe you can get plastic/nylon gears for them. I wish the Hyper7 diff was the same, because it would be alot easier to fit a 32p spur gear on these types of diffs...
-Nick

[Combatcm]

Ok I guess I'm going to have to stick with the hardened pinions. Your talking about these right? They won't grind on me?

http://starluckrc.com/catalog/product_info.php?products_id=42

I can't pick a motor though, I will run both dual 6 or 7 cell packs, but even with a 16T pinion and the 10T motor, I'm guessing the buggy will go well over 40mph which is good enough for anything. But I mean, if I'm gonna pay $600, why make it go just as fast as other buggies. I think the inablilty to gear down the 8T if need be is the reason I don't want it. Ehhh, I'll stick with the 10, I want more run time, which is good, cause I'm going to have to buy a bunch of new packs. I also need to pull 10 minutes for races.

I'm going to stick with the warrior 9918, this will put all the conversion gear to about 350, as opposed to 350 for the schulze ESC.

[starluckrc]

The hardened steel pinions aren't listed. They are a limited production run. Once they are gone, that will be it unless someone can do it for us cheaper. These are $25 each to cover the cost to have them made.

[Combatcm]

that's not that bad considering hardened clutch bells are around $16, and even then, where else can you get them?

[Combatcm]

Hey starluck, I was wondering if you got my order, I bought the 9L through the main page, and I sent an extra 25 to cover the pinion. I would of sent it in one payment, but I just wanted to through the site.

What do people think of this ESC, it is marginally less expensive than the other ones,

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=5927251980&ssPageName=STRK:MEWA:IT

[Chase023]

I might have hardened Module 1 pinions for sale soon because I am getting some made for myself soon.

I will let you guys know if anyone is interested but like Jamie said it is expensive.

[studysession]

If you do a seach on google - you can find a few sites in the US and out of the US that sell MOD 1 pinions.

[Combatcm]

Hey, someone post some videos of these things. I can't wait, that video that was posted with it running on 12 cells and it was a rocket.

I need some information on braking. It seems that this method would be more stable when braking because of the all wheel drive, but it will have limited tuning. Mines got the stock fluid in it and need to change.

I was actually thinking of throwing the linkage back for just for the rear, and maybe using a 3rd channel to lock them to spin the car like a handbrake. Or use front and do burnouts at the start.

[racinlosi]

Well, I guess I ended up keeping mine. So if you think you will sell yours, you won't. Your love for it will kick in harder than normall, and be forced to keep it!:D

[DualBL]

Combatcm, pics and vids?
enjoy: http://8ths.dualbl.com

racinlosi: good boy.

-Nick

[studysession]

Very nice Nick!

[Combatcm]

I will try to post some videos of mine soon, I still need the ESC.

[racinlosi]

racinlosi: good boy.

-Nick


Lmao Dual!

I am building a computer right now because the one I have, well, sucks! So I am thinking about getting a 8L or 10L Motor from Starluck and a Warrior 9918 for my buggy afterwards, but it might be a while seeing the computer I am building is going to cost alot of $$$. But if all my idea's are put to work, I might want to do a Dual BL setup with 28 cells, 14 each motor(this is just in the thinking prosses right now). That and I need a rear chassis brace for the buggy also! So now I need to get to my serious thinking and look at all the idea's I have possible for my buggy in a good price range, lol. :D

[Combatcm]

I got my motor today, these things are really big. The pinion is nice and meshes great.

Does anybody know where can get those L shaped battery mounts? A lot of people use them and I don"t know where people find them.

[studysession]

1st - what motor is that? 2md - what L-shaped battery mounts?

[Combatcm]

http://home.comcast.net/~milemarkers/Grenadier-HDRearMechanics.jpg

Like those ones.

The motor is a feigao 9L.

I think I'm going to make a mechanical rear brake that activates only at the end of the trigger throw, so it won't strain the motor. When I raced I always whipped the rear through the sharp corners. I can't think of a way I can dial rear bias with no brakes except for the motor. All my diffs right now are stock loose.

[studysession]

OK - They are called Battery Cups - made by Team Associate for pan cars. Get them at Tower Hobbies.

[Combatcm]

Thanks.

[glassdoctor]

Thanks.

What you need to for your brake action, is a one-way for the front.

Someday when I finally get my BL buggy done, I plan to try a one-way that is made for the Revo. I don't recall who makes it, but it looks really nice.

It will mount in place of the front driveshaft on the center diff. Then you will need a shortened shaft to reach the front diff. If that doesn't make any sense, then think of it as part of the front driveshaft. It will allow the front wheels to freespin off-power, so you only have rear brakes.

I run my 1/10 4wd like this. Most people prefer racing with a one-way. I don't know any 1/8 buggies that run one though, because you can adjust f/r bias, as you know...

[Combatcm]

such as

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXCJV1&P=7

You just have to hope the action goes in the right direction.

[Craps]

Anybody interested in buying my electric 1/8th scale buggy?

I am thinking about selling it and was wondering if there is any interest in it for some serious speed and the ultimate set up that I have read about in here. I don't think I have seen a better set up than my buggy has for some pure out right speed and power.

Just wanted to see if there is interest out there?

I may keep the Schulze 40.160 ESC and I may just sell it as a roller with a B50XL motor mounted up?

I am going to be really hitting the World Record Speed Run Project very heavy and do not have time for the 1/8th scale project anymore. My project is going in a direction nobody has even considered yet for this and I will have huge advantage with it depending on the track they choose to have it at. I can't say what it is, but with my history in here, it will blow your mind with what I am planning to build. :eek:

[Rotary Rocket]

Craps,

Are you going to attached 4 motors directly to each wheel and get about 60000 rpm out of it...

:D

[Craps]

Craps,

Are you going to attached 4 motors directly to each wheel and get about 60000 rpm out of it...

:D

RR
No, you are way off and I will be running just one motor, but the chassis/car is the big secret and will be a big difference depending on what venue they choose to run this at. The propulsion system is totally different than anything mentioned in here and will be very powerful as in the 30 to 50 hp range.

If you are going to the event, better bring your "A" game if you are going to beat me!

Enuff said!

Does anybody want to buy my 1/8th scale?

[OptimaMan]

30-50 HP??? !%^$%*@#!$@$# You're not talking about electric then. I don't know of any brushless motors in the 30,000 watt range!! Or even batteries to support that kind of power. You're not talking like little jet engines or turbine engines are you? Just very curious Craps...

[e_lm_70]

30-50 HP??? !%^$%*@#!$@$# You're not talking about electric then. I don't know of any brushless motors in the 30,000 watt range!! Or even batteries to support that kind of power. You're not talking like little jet engines or turbine engines are you? Just very curious Craps...

Even a jet engine (in the RC word) is not capable to pump more then 10HP ! And if you want to take the jet power and convert in rotational power ... then the efficiency could be quite poor !

e_lm_70

[Craps]

30-50 HP??? !%^$%*@#!$@$# You're not talking about electric then. I don't know of any brushless motors in the 30,000 watt range!! Or even batteries to support that kind of power. You're not talking like little jet engines or turbine engines are you? Just very curious Craps...

I have said too much already and you guys keep thinking small will be fast! You have been used to small scale and small batteries. It's out there, you just have to know where to find it and how to get it. The propulsion and fuel system are pretty generic, but the car/chassis will be state of the art and one of a kind that incorporates this particular propulsion system that nobody has even come close to thinking of and it fits within the rules.

Enuff said!

[Combatcm]

This other digicam I have takes way better pics. Check out the center of gravity...this thing is low! Anyone like the motor placement?

One problem is the batteries have very little room. Between the rear suspension plate and the center spur, there is about 5mm of play when the battery is on the chassis. So I most likely will not fit both battery cups that I wanted. I don't want to get custom packs because I like the low profile of the 6 cell packs, and I don't want to rely on all custom packs. I could mount them on the rock guards but it will handle better with them inside. Every spot on the plate will be taken, this chassis is stacked!

[Rotary Rocket]

Very nicely done. You will have the best handling buggy if you can pull off this set up.

You should also think about flip floping the steering servo and motor. The motor will produce troque steer to the left with your motor in its current position.

[studysession]

RR - Why will it do that?

Combatcm - love how you placed the motor. I might try the same thing myself.

[Combatcm]

I think he means that since the motor weight is on the left and the car will also torque steer to the left, it might handle wierd. Its too much work for me.

[studysession]

I am thinking of getting the Warrior 9918 for the Hyper 7 conversion I am doing. Will be a few weeks because of funds. I want to run 12 or more cells.

What would be to many cells to run on this?

BTW nice pic.

[Rotary Rocket]

I think he means that since the motor weight is on the left and the car will also torque steer to the left, it might handle wierd. Its too much work for me.

Torque steer has to do with the rotation direction of the motor. Due to the motor direction your buggy will want to rotate on its longitudinal axis to the left, so by placing the motor on the right side of the buggy you will make this negative effect be less noticable.

Keep in mind this is in the current direction of the motor, so for people who have their motors faceing forward you would want to place the motor on the left hand side.

[pinolelst]

torque steer ?? Not sure if that small a mass that close to the centerline would have much effect if any on steering particularly since the driving forces are at the far outer corners of the vehicle.Maybe a tendency for a slight chassis roll??. Maybe your experience dictates otherwise though not having a central motor mounted electric like that myself.If you hold your car by the front bumper in the air and apply full throttle does it torque to the side laterally or want to rotate longitudinally because of the motor and gearing??
Just trying to educate myself. TIA

Peace

[sugs]

I've been playing around with that motor position for a while now. I think it gives the most room for the batteries, plus the added bonus of having them more centered. I'm guessing there will be a little torque steer, but not enough to adversly affect the handling of the car. You could probably compensate for it by adjusting battery position. Just my two cents.

[Combatcm]

But then you think about how the center diff has more mass and spins the opposite direction

It's not really aproblem for me. It works really well in its current position. Mainly because my motor mount flexes a bit when a lot of pressure is applied, and the motor is actually resting on the chassis brace, so that when the spur and pinion try to separate they wont, because the can will press the brace and not move.

[studysession]

If for the direction the diff is spinning. Just change any 2 wires and the motor will go other direction. Problem solved.

[studysession]

Later I will mount mine like that and take a couple of pics. I still do not have the controller yet for my H7 though. Still just using a brushed motor to compare position and stuff.

[studysession]

Question -
What OFNA Diff's come with or allow the plastic spur gear?

I have been searching EBay trying to figure out which ones had plastic spur gears OR what would be good replacement for stock center Hyper 7 diff that does now allow replacement for plastic center gear.

Thanks!

[Combatcm]

9.5 doesn't, I think someone said the H7 doesn't work also, And I know the LX pro, MBX have the bolt on spur, and the comp might. You can throw a LX pro one on maybe.

[OpIvy]

yeah, MBX R2, and the some other's might..
9.5, and Hyper7's don't work.
check out www.ofna.com, and go to the pdf assemblies of the buggies, and it shows what kind of diffs allow the spur to be changed w/ out opening the diff.
-Op

[studysession]

Cool thanks!

[studysession]

OK - I am currently high bidder on an EBay auction for a diff for an OFNA LX. The plastic replacement gears for the OFNA diffs. What pitch are they?

Thanks!

[starluckrc]

mod 1

[studysession]

Then which ones do people put on that make it 32p? And how do they attach to the OFNA diff?

[studysession]

....................................

[OpIvy]

Most use Emaxx spurs, and drill the center out.
-Op

[studysession]

Not sure why but having trouble uploading pictures here.

Anyhoo - Hopefully no problems with shipping. But I won the auction for the OFNA diff.

Is this correct TMaxx slipper spur gear I need for it???
http://www.carttonic.com/catalog/index.php?file=catalog&action=catalog_productinfo&uid=466&clist=0,10328,10502&pi_id=12265

Thanks!

[Mr. Constructor]

Yep, seems to be a good choice, but the holes for attaching it are 4 and not 3 so you have to bore new ones, but anyway this could be a good option !!

Good Luck !!

By the way, how much was the diff at all ??

[studysession]

The diff was $20 + shipping brand new with full brake assembly and everything to hold the center diff into place on an OFNA LX. Bought diff on EBay - hopefully it arrives.

Just now need to get a plastic spur for it.

[studysession]

Saw some diffs for same mak of buggy ended for cheaper prices. Could not believe that they were going for so cheap. I saw the cheaper ones after I already won the auction for the one.

[studysession]

Anyone know of a spur that will match up to the OFNA diff that does not need any kind of modifications?

[rstnboy]

I don't know of any 32 pitch gears that don't require modification. The gear I used to do the proof-of-concept testing (using E-Maxx motors and pinions) was a hollowed out E-Maxx gear. It worked ok but I decided to go ahead and change everything to Mod 1. Here is the link to the Mod 1 spur I used:

http://www2.towerhobbies.com/cgi-bin/wti0001p?&W=000568591&I=LXBM16&P=K

I didn't have to modify it in any way - it directly bolted in.

[Combatcm]

Ok, everything is in and I just soldered all the connections for it. But there is a problem, the manual sounds like it was just translated by a text translator and just left the way it is. I really need some help. Programming ESC's is not my specialty, I usually just plug it in forward/neutral/brake/done, and if it doesn't work, do it again.

I also notce that is says something about a switch, but there is no switch.

The main problem is it doesn't go into "programming mode". The motor just starts twitching the second I plug it in. It does receive signals, but it doesn't go full throttle, and I had to set the trims to make it stop.

I won't post any pictures till it is done.

[OpIvy]

you have the 9918 correct?
if i remember correctly..
you need to pull one of the 2 jumpers.
one jumper is for BEC, and one is for programing.
I can't remember which one to pull, or if it needs to be in, or out to program it..
on my 7018, the jumpers were kinda hidden under the heatshrink
hope that helps a little..
-Nick

[Combatcm]

I got it, my ESC was mounted so there was no way to check in it. I looked next to the positive power wire and there it was, took some needle nose pliers and got it out. From then on it was normal programming through the manual.

My buggy is finished. There are some things I could help a little, but it is runnable. The mounting is kind of sloppy, and I never got around to slotting the motor shaft, but I threw some threadlock on it and I hope it doesn't break free. The only problem is its 1:45am and...wait, its electric. I guess I can give a run before sleep. Uhhhgg, now I have to charge two packs. I did get a pair of maxx packs, they said SCR on them and they are good cells.

[Rotary Rocket]

If you are using the buggy center diff (with a 51 tooth spur), what size pinions are you guys using?

I got a 12 tooth Mod 1 pinion from Starluck, with a 51/12 gear ratio what is a good brushless motor to use on 12 cells in a 1/8 buggy?

I will actually be using 4S4P LiPo (8000 mAh). Would a Hacker 7L be too hot of a motor for a buggy geared 51/12?

Thanks for sharing your experience.

[Combatcm]

I got it running. This setup really packs a punch. I would estimate speeds of 45mph, but I have a GPS so I can give the real speed later. To me it's fine, but to other people the cogging might be to much. If you ease the throttle it will cog to 1/4 and then start jittery movements from there. At half throttle it will start moving pretty good, and if you jam the throttle going more than a slow walking speed the tires will light up.

After running my maxx paxx, the best run I had was 2 minutes and 14 seconds of yard bashing. This does not seem right at all, but I may be underestimating these motors. I'm going to deep discharge them and see if its helps, I now need to rely on my myriad of mismatched packs.

It makes all these wierd electronic signal noises.

[Combatcm]

I ran it with one 1500 hobbytown pack and a real 1900SCR pack, and I made it to 4 minutes. They said those maxx packs were 1900SCRs pffffft. If I can't revive them trinity is going to have some explaining to do. But it doesn't help that the second I opened the box a big card that said "No Warrenty" popped out. Oh well. I'll see if I can get some more info on another board.

[studysession]

You are only getting 4min run times?

[starluckrc]

You need good GP3300 cells to get the best out of the system. Even my nice 2600's drop voltage bad under load. Our batteries were never meant to do what we push them to with the big brushless systems.

[Combatcm]

Yeah, just 4 minutes. It was actually exactly 3 45. That is all you can expect out of sport 1500's. The motor averages some 60 amps constant. Those maxx paxx had me stunned when I did 4 or 5 runs around my yard and they started to die, they are cycling now. I'm going to get a pair of 8 cell double hump packs from CBP when I get a chance. Either Nicd 2400's preferably or GP's.

[Craps]

My 1/8th scale has been sold!

I still have the electronics.

Now for the Speed Project to blow everybody's minds!

[Mr. Constructor]

maybe you could gear it higher ?? (smaller motorpinion, wich one are you using now, motor and maingear??)
at wich motor, 4min seems to be very hard and the cogging isn´t normally that bad on those esc´s not even with their bad software !

3300´s hold up for around 12 + min in my 8ths, but the gearing is way more imoprtant on BL than on nitro or normal electrics !!

(have you ditched off the orange dip, then programmed it and before disconnecting the batts take the orange back or the esc might loose its programming !!)

[TXTRCR]

I love the smell of burning brushed motors in the night time. I saw every ones posts, and i got inspired. I had a 1/8th scale roller( Ultra LX Pro) and a Starter box so i desided to put the two together. It took about 2 hours of cutting and grinding and stripping parts off and putting them back. I took the gear off the center diff and installed the pulley from the starter box, took a little bit of grinding on it but the four bolt holes lined up perfectly to the differential. I then cut the twin motor mount in half and mounted it on the left side of the buggy ( looking at the buggy from the back of it). i used the 550 motor that was in the starter box and ran a belt from it to the diff. i then took the entire radio tray off the right side and cut off every thing but the steering servo mount and i remounted it to the frame. I stacked 12 cells on the right side behind the servo, 6 cell packs two layers. i mounted an astro flight 212d speed controller under the rear center drive shaft. Pretty challanging to drive as it only has GO!, no stop no reverse. the motor lasted alot longer than i thought it would, i figured on it smoking in the first pass. I got about 4 or 5 passes of what looked like 15 to 20mph and when i pulled through the grass to get it back to the garage the motor let loose a couple of flames and a big ball of smoke. The motor is still smoking as i type this. This stuff is fun. i plan on swapping the 550 for a 775 Cordite SS1. that should prove to be more fun that anyone should be allowed to have at one time. 30+mph and no brakes, i think ill wear shin guards on the next run.

[rstnboy]

I finally got everything put together including the nice-to-have items like battery boxes and a heatsink for the 8L motor. I am using the Ofna MBX R2 buggy with a Warrior 9918, Feigao 8L, and 12 GP 3300s. Modifications include centering and raising the center diff, laying the steering servo on its side under the front drive dogbone, fabricating/modifying numerous braces, constructing a motor mount, and making a mounting bracket for the ESC just forward of the rear shock tower. The maiden voyage was tonight and it was something to behold. I don't have an accurate speed measurement but it was faster than my E-Maxx on 14 cells by a huge amount :eek: . Here's links to some pics (just replace the ****** with r-c-p-i-c-s without the dashes):

http://www.******.net/img/43707
http://www.******.net/img/43706
http://www.******.net/img/43705

[TXTRCR]

i posted the top view, hope you dont mind. its a very clean setup nice work

[studysession]

Start posting new stuff here:
http://forums.radiocontrolzone.com/showthread.php?t=183460

[ineed2selmycars]

I got it running. This setup really packs a punch. I would estimate speeds of 45mph, but I have a GPS so I can give the real speed later. To me it's fine, but to other people the cogging might be to much. If you ease the throttle it will cog to 1/4 and then start jittery movements from there. At half throttle it will start moving pretty good, and if you jam the throttle going more than a slow walking speed the tires will light up.

After running my maxx paxx, the best run I had was 2 minutes and 14 seconds of yard bashing. This does not seem right at all, but I may be underestimating these motors. I'm going to deep discharge them and see if its helps, I now need to rely on my myriad of mismatched packs.

It makes all these wierd electronic signal noises.



the noises could be from the throttle trim being just a tiny bit to much or to low... when u let go of the throttle does it keep rolling or stop fast?

[mikeyr00]

Hey that Ofna is pretty cool looking. I did just about the same thing with mine, moving the server that is. I have mine posted in the other thread listed above. How did you attach the servo? I used some servo tape and it seems to be working pretty well. I'm also using the HV Maxx setup from novak so there is pretty much no cogging at all, only when the batteries get low. I drive in the living room a lot harrasing the dog. I'd like to get mine as clean looking as yours but I just havn't had the time to mill out the parts I want. Does mounting the motor high like that cause any stibility problems? If it roles, does it hit the motor at all? I didn't think the two screws into the rear plastic diff mount could hold the motor that high and handle the torque. Great job!

Mike

[Gojira]

hi,new to the forum just have a few ? why not use a center slipper like the one on the hpi nitro mt2 that and whats the issue of converting the gears to 48pitch any replys welcome

[Craps]

Update!

I abandoned my project months ago due to the center diff ripping out everytime I ran because of the huge amount of torque the Hacker C50 10XL motor had with over 22 volts hooked to it and I really think I needed to upgrade to newer model of 1/8th scale like the Mugen MBXR-5 instead of the MBXR-4 I was running.

I am toying with the idea again to build another and I still have the ESC and Motor. I may build an electric truggy since there is alot more room under the body to have 18.5 volts and enough mahs to run a 45 minute main non-stop along with larger tires to plant the excess power.

I may even go with the OFNA model due to the center diff is steel and has the spider gear system with more gears that would hopefully be tougher.

The pinion gears I had made with the mod1 pitch were sold out very fast by Jamie at www.starluckrc.com and I have not heard of anybody tearing one of those gears up.

Good luck to all!

[scoob]

Craps, PLEASE DO IT!!! I would love to see that thing run at NVR. 4WD man, I guess I am just obsessed with that lately :) .

[Combatcm]

The pinion gears I had made with the mod1 pitch were sold out very fast by Jamie at www.starluckrc.com and I have not heard of anybody tearing one of those gears up

Hell yea, aside from being a little shiny on the mesh, the pinion gear and the spur have no wear.

Though I could use a 12T or 11T for a truggy covnersion.

[vad]

Update!

I am toying with the idea again to build another and I still have the ESC and Motor. I may build an electric truggy since there is alot more room under the body to have 18.5 volts and enough mahs to run a 45 minute main non-stop along with larger tires to plant the excess power.

I may even go with the OFNA model due to the center diff is steel and has the spider gear system with more gears that would hopefully be tougher.

The pinion gears I had made with the mod1 pitch were sold out very fast by Jamie at www.starluckrc.com and I have not heard of anybody tearing one of those gears up.

Good luck to all!

Craps,
Did you ever try out 12 cells for racing and any other motor than the 10XL.

In the MT unlimited class you should have anyone complain about you racing them, from my understanding there are no rules set for the MT unlimted class.

[Craps]

Craps,
Did you ever try out 12 cells for racing and any other motor than the 10XL.

In the MT unlimited class you should have anyone complain about you racing them, from my understanding there are no rules set for the MT unlimted class.

I raced it with the li-po equal to 12 cells that is 4 li-po cells (14.4 vs 14.8 volts) and I thought it needed more. The system was way over discharging the pair of 1st Generation Thunder Power TP8000-2S4P Batteries that were rated back then at 5C discharge rate. Now the newer ones are rated at 12C to 15C and can probably take it. I also went to 6 li-po cells that is 22.2 volts and burn up a Schulze 18.97 ESC, so I went to the big 40.160 ESC. The 22.2 volts is overkill and generates way too much heat. It needed a 5 li-po cell pack that has 18.5 volts and for the 45 minute non-stop run will take around 10,000 to 12,000 mahs to power that system.

As far as complaining about the rules for Unlimited MT, let me build that and try to race it. You think they whine and cry now about the Production vs Truggy thing, they will really cry about the huge power/runtime advantage electric has. Been there done that with the 1/8th scale buggy!

Note: Craps don't use or recommend NICKEL batteries for RC!!!

[Gojira]

im building a hyper7 what motor or motors do you recomend for use with 12-14 nimh cells and 18/52 gearing I would like to be as fast or a lil faster then a nitro buggy nothing to crazy

[tcolesen]

If you are on a budget, then a Feigao 9L should work well. Maybe a 10L (it would be a little slower though).

[Gojira]

are the nemesis blue motors any good,i was thinking of getting the 10L

[tcolesen]

Those and the Feigao motors are the same. Are you looking at the ones from Fine Design RC? If so, go with Starluck RC and get a Feigao for much cheaper.

[Gojira]

thanks for the heads up on the motor,what esc would you recomend and thanks for the help

[tcolesen]

The BK Warrior 9918 is what many people run.

[vad]

has anyone had a chance to race, not bash with a schulze 18.129 or 18.149? Please post opinion about these ESCs. I know they are pricey, but Im looking for a very smooth ESC, on throttle, off throttle and braking, for a 1/8 scale converstion with a 8L or 10L motor and 12 cells.

[Craps]

has anyone had a chance to race, not bash with a schulze 18.129 or 18.149? Please post opinion about these ESCs. I know they are pricey, but Im looking for a very smooth ESC, on throttle, off throttle and braking, for a 1/8 scale converstion with a 8L or 10L motor and 12 cells.

They will not work with the Futaba HRS reciever nor they can not handle 22.2 volts. Can you say fire!

[Gojira]

can u run an 8L in a buggy on 14.4v or do u need good lipos to get it to perform corectly

[tcolesen]

The 8L is often considered too "hot" for 1/8 buggies. I run one, though, and it does heat up more than I would like, and does the same to the controller (4s Lipo). At this point I am running it on 3s Lipo to keep the temps down, even though I have low gearing (overall ratio of 13.23).

[Gojira]

cool thanks for the info,I think im going to run an 9L on 16.8v of 3800 mah nimh. two 7 cell packs they move the emaxx with no problem

[studysession]

I have been using a 10L on 12 cells. I am very happy with it.

Here is my Hyper 7 PBS:
http://www.rcuniverse.com/magazine/article_display.cfm?article_id=467

[Gojira]

I have been using a 10L on 12 cells. I am very happy with it.

Here is my Hyper 7 PBS:
http://www.rcuniverse.com/magazine/article_display.cfm?article_id=467
what batteries and how fast of a top speed are u getting

[Gojira]

oh yea and what causes cogging?

[tcolesen]

If you look at the bottom of his review, it says what gear was used. Cogging is like stuttering of the motor usually caused by the BEC not delivering enough power, or the regular batteries not supplying enough power. This is why you need good batteries with brushless.

[starluckrc]

On 14 cells, the 10L will be plenty in the buggy. Most nitro buggies are turning around 30k rpm or less under load. Your buggy will be much happier (along with the motor, batteries, and esc) if you shoot for the mid 30k rpm range and definitely stay below 40k.

[evilGearhead]

hey, quick question,

would the novak hv-maxx system for the e-maxx be sufficient enough for a buggy conversion?

12 cells

[tcolesen]

There is someone who will try it out, but we haven't heard the results. Theoretically, I think the HV-Maxx might be too weak.

[Craps]

Just wanted to bump this thread to show others here this isn't my first rodeo!

[glassdoctor]

That was a good thread Tim... no doubt there are a lot of guys that were'nt around back then.

It's funny now to look back and see all the nickel cells and even brushed motors being run.

[Craps]

You know me I have been li-pos and brushless from day 1 and i don't know of anybody that has been racing with li-pos on the off road longer than me. I went through alot of the bashing and hate with them too. Now look at everybody racing with li-pos and brushless with ROAR on the verge approving li-pos that I always heard they would never do and racers would never accept them!!!!

This has been a hell of a year for me!

[chewie]

in my 8ight i used a 8xl. power was insane and top end was around 45 mph... i was using 5000 maxamps 7.4 volt packs wired in series.. the feiago motor blew up on me... you could say i got my 80 bux worth from it.. but thats about it..
i currently bought a rc8 just to do the conversion for.. im waiting for it to come back
dan at rcproductdesigns.com is doing the conversion for me.. hes a great guy to deal with..

there will be a class for these at the crcrc midwest championships. and we need people to enter.. so if your interested in being a part of electric 1/8 history.. cmon and join us..

[Craps]

I thought I would bring this thread up since I started in March of 2004 and have been racing 1/10th scale trucks for the last few years since I had the my electric 1/8th scale. I am now returning to the electric 1/8th scale now that Novak has a great conversion kit that is the best on the market.

My Nanda Buggy with Novak Power!

http://i29.photobucket.com/albums/c264/Dice193/Electric%208th%20scale/DSC04552.jpg

http://i29.photobucket.com/albums/c264/Dice193/Electric%208th%20scale/DSC04555.jpg

http://i29.photobucket.com/albums/c264/Dice193/Electric%208th%20scale/DSC04556.jpg

http://i29.photobucket.com/albums/c264/Dice193/Electric%208th%20scale/DSC04559.jpg

http://i29.photobucket.com/albums/c264/Dice193/Electric%208th%20scale/DSC04560.jpg

The Nanda is very similar to a Kyosho and I even used the Novak Kyosho conversion kit that was a perfect fit.

I did mount the ESC on the same side as the motor and in the front. I like dual battery trays with one on each side to balance the buggy.

Nanda 1/8th Scale Buggy
Novak Conversion kit (Kyosho)
Novak HV Pro ESC
Novak HV 7.5 motor
Elite li-po batteries 2S 6600 mah 7.4 volt 30C rated (X 2)

I'll be using 2 Thunder Power chargers and balancers to individually charge at 6.6 amps.

[kufman]

Novak has a great conversion kit that is the best on the market.

I like your enthusiasm, but you are dreaming.

[Craps]

The motor mount system and the ease of assembly is alot better than the motor plate bolt together systems. I have now owned both and perfer the Novak over the other type anyday.

Novak has done they're homework on this one with great set up!!!!

[kufman]

The motor mount system and the ease of assembly is alot better than the motor plate bolt together systems. I have now owned both and perfer the Novak over the other type anyday.

Novak has done they're homework on this one with great set up!!!!


It is only great if you own a Novak motor... other than that you can't use the Novak conversion. :confused:

[Caster Racing]

We got pictures of the pro kit and are going to be ordering some soon. The fusion sport is out there and makes life convenient if you don't want to mess with conversions...

casterracingusa.com for details....

[rccardude04]

A customer of ours has the Novak system.

It ran pretty well, nice throttle response and all.

I do not like their motor mount. It's easy, but if you really load it, the thing can flex. Brushless makes more torque than nitro by a long shot, and this can cause unwanted twisting in the chassis that can totally hose up your gear mesh. Other than that, it's not bad though.

My issue is with the motor/ESC. Most offroad tracks are kept watered, and Novak controllers, especially the HV ones, really don't like getting wet. They tend to get cranky.

-Eric

[Ball Racing]

I love my losi motor mount system, one screw, and take the motor off.

[Craps]

No signs of and I don't see how the Novak motor mount system in mine can flex like the motor mount plate bolted to or even made as part of the center diff tower because the motor is held down in the center of it rather than hung off the front of the motor with the weight of the motor hanging off the face of it. I have seen how the torque of the motor flexes this type of motor mounting that tears up pinion and spur gears.

I have had both kinds and Novak's center motor mounting system is the best one by far. Novak has done they're homework on this system.

Thank you Novak!

[Craps]

It is only great if you own a Novak motor... other than that you can't use the Novak conversion. :confused:

I perfer the sensored Novak system over the sensorless motors of my past. Sensored motors dominate the 1/10th scale world because of there smoother intial power band.

Of course the Novak running on 4S is not as powerful as the old 6S powered system I used to have, but I am not making straightline speed runs in the street knocking down mail boxes. I am racing on real off road tracks against nitros on tracks that need a useable powerband and throttle curve that with Novak on 4S is plenty of power to get the job done and will be faster on the tight technical parts of the track where races are won than some over powered system that all it does is spin the tires making it hard to drive smoothly and tears up the drive train.

My Novak is for making fast lap times on real off road tracks and not for how fast I can knock down the mail box in front of my house.

Novak has done they're homework and provided a great conversion for 1/8th scales.

[GSMnow]

I have to agree with Craps about the OVERPOWERED setups. Have way more power than the chassis can put to the ground just makes it near impossible to drive smooth. Running my Mamba Max in a 2WD stadium truck was too much power to race. Putting the same MM 5700 system in to my 4WD buggy was a night and day difference. It is just about as fast, but so much easier to control. On the data logger, I can see how much power it takes to spin the tires. The current falls off when they break loose. My under 4 pound 1/10 takes about 300 watts without too much wheels spin. It peaks over 500 watts if the track conditions are perfect so the tires hook up, but even in the best conditions, this power level lasts a fraction of a second. The whole infiend runs bewteen 150 and 300 watts when I am not braking and/or turning. I am trying to scale this up for an 8 pound 1/8 scale. Twice the weight should need twice the torque to match the acceleration G's. If I am confined to the same track, the top speed will be about the same, so that should mean just twice the watts, or 1000 watts available, and 500 to 600 watts relatively constant in the tight accel areas. I am also looking at just 4S. 14 volts (4S under load) makes 1000 watts at just 70 amps. Geared to hit about 40 mph, it should top 1G acceleration in the 60 to 80 amp range. This is very mild compared to many of the 6S and up conversionns.

As for sensored vs sensorless. I honestly believe it makes less difference than you think. My Mamba Max system is incredibly smooth once you are rolling over 1 mph, and even the standing start is great. This is not the case with many other sensorless systems though. Some are down right terrible at low speed so it is certainly not a blanket statement. Sensored systems will alwyas have the edge at very low rpm, but not much racing happens that low. At higher rpm, the "smoothness" of the Novaks seems to be due to their higher series resistance which gives the motor a little softness in responding to input, but it also makes some heat. I was able to do a side by side comparison between a Sidewinder 5700 system and a Novak SS5800 with a sintered rotor upgrade. The track was very tight and neither car could top out in the space. Both were geared for about 35 mph on 6 cell NiMh with IB4200 packs. The Novak almost had a sluggish feel. It was not slow by any means, but it would never snap from a trigger input like the Sidewinder. I had to roll on the trigger with the sidewinder, where I could yank it pretty hard on the Novak. Whe I got the feel of both cars, I went for top lap times, and I was just a tick faster in the sidewinder on my best laps, but a little more cinsistent, with a better average lap speed on the Novak. I think this was all due to it just having less torque available to the wheels so I didn't need to be as careful and the wheels would not spin unless I did something stupid. But even my best lap on the Novak could not match the good laps on the sidewinder. There was a clear max power deficit. To be fair to Novak, the 8.5 turn 5800 is rated at much less wattage than the Sidewinder 5700 package, so it makes sense. But now the bad news. When I really got dialed in with the Novak and was getting on the trigger as soon as possible out of every turn to really take advantage of the "smooth power", I only got about 8 laps before I thermalled it. The motor and ESC were both blazing hot. I ran the entire pack out on the Sidewinder, and was pushing it as hard as I could without looping it and it only got the motor and ESC warm, but the battery was smoking hot when it hit the 5.0 voltage cutoff. A Novak 6.5 would be a more fair comparison to the MM 5700 on the power side, and probably would not have thermalled so easilly.

Scaling this knoweldge to the 1/8 buggy is not that easy. The Mamba Monster 2200 KV system is TOO MUCH POWER, even on 4S. The solution to this is proper current limiting, but noone is doing it yet. My proto type 1/8 test is going to be using a 1/10 Mamba Max ESC on 4S with external BEC. And I think I have landed on the Medusa Afterburner V2 36x60 mm 2000 KV motor. The constant current rating is 87 amps, at 4S that is about 1200 watts, or maybe too much, but close. I will probably gear a little faster to tone the torque a touch. I will report when I get it together.

[SpEEdyBL]

I have to agree that sensored makes less of a difference. I own an MMM esc and an HV-maxx esc and the MMM, when used with the novak hv 4.5 motor is smoother through the top 95% of the powerband than the HV-maxx esc. The smoothness of the MMM breaks are unbelievable. It just seems that the MMM has more "steps" or more levels of throttle input than the hv-maxx.

The MMM still cogs when you jam the throttle. You cant do a wheelie with the MMM when you can with the HV-maxx, but you can roll the throttle up from as low as a 1mph crawl with the MMM.

And of course these results would be even better if a neu motor was used.

[GSMnow]

The MMM still cogs when you jam the throttle. You cant do a wheelie with the MMM when you can with the HV-maxx, but you can roll the throttle up from as low as a 1mph crawl with the MMM.

And of course these results would be even better if a neu motor was used.

For my 1/10 truck, I am still torn over the choice. I have the Mamba Max ESC, and want to go Super Stock (13.5 turn) but the ROAR legal Novak style motors just don't run as well sensorless. A similar KV motor without a stator stack seems to run so much better. The Neu motors do have a stator stack, but they are also 4 pole which certainly changes things. The Novak HV motors are just the same ROAR design, just longer, so no surprize you still have the minor cog issue. If you have it rolling at 2 mph and punch it, it should pull a wheelie for you. My 2WD truck would pull a wheelie from 20+ mph.

Brushless 1/8 is growing, and it will become huge. I just hope the rules don't kill it. Keep it pretty open and simple and many drivers will show up. Unlike ROAR 1/10, powerful sensorless motors need to be allowed.

[kufman]

Just because you run a 6s setup doesn't mean that it is overpowered. If you use the appropriate motor and gearing, you gains are in terms of ESC loading. Higher voltage, less current = a happier esc. How many real hybrid automobiles do you see using a 12V system? None is the answer. Higher voltage is the way to go for efficiency and reliability. Running 4-pole and 6-pole sensorless motors is just like running a sensored 2-pole. Running my 6-pole mega on a Mamba Max, RS-Pro or Schulze U-force, I can't even tell it is sensorless.

I stopped by the Novak booth today at the hobby show in Chicago and had a nice little chat with Charlie and Bob. They are nice guys to talk with even if I disagree with how they make their products.

I also stopped by the Tekin booth and saw their new 1/8th controller and it should be a great little controller when it is done. :D

[Craps]

I was able to do a side by side comparison between a Sidewinder 5700 system and a Novak SS5800 with a sintered rotor upgrade.

First off you are comparing an old out of date Novak system that has been replaced by the Novak GTB ESC for around 3 years now.

I use the Novak GTB with a Novak Velociti 7.5L motor in my 1/10th stadium truck using a 2S 8000 mah li-po in 30 minute races with no fans and no problems at all. I finished 2nd in both RC Pro Nitro Series gas/electric truck class in the Northeast and the East Divisions. I will be racing for 45 minutes without a battery change at the RC Pro Nitro Series National in Texas next month with no fans.

I have raced long race 1/10th scale electric since 2003 using li-pos and brushless the entire time. I have used alot of systems from Schulze, Plettenberg, Mamba, MGM, Hacker, Lenner (sp) and settled on Novak after getting beat by one often. My laptimes were faster right off the batt due to smoother powerband and no intial start up cog.

I will give everybody a tip in all electrics racing in long races and that is to oil or lube the bearings at least about every 1 hour of runtime or do like I do and lube right before every 20+ minute main after the quals. This will stop the heat problems and will make the motor last alot longer too!

I am just now getting back into the electric 1/8th scale and I went ahead lubed the bearings when I installed it brand new. I am still not sure the fans are really needed if the gearing is right and everything is lubed properly.

Let me add that better racers than me that kick my butt in a spec class like the slash class use a Mamba system in 1/10th scale truck and I lap them because they can not get the sensorless close to being smooth on a dried out slick track where a very sensitive and smooth throttle is needed in those real tight corners. I will admit he is faster than me on the straight a ways, but that is not where offroad races are won! I will give up 10% of most tracks that are a long straight a way to be faster on the other 90% of the track that you actually have to turn left and right on!

Sensored motors DOMINATE the 1/10th scale racing world.

I am not wanting this to be a bash thread, but an informative one for all to share info. With that being said, please race with whatever you are most comfortable with or even whatever you can afford.

Good luck to all!

[GSMnow]

CRAPS..
I won't say the Novak is not a good system, it is smooth and trong. But are the HV's strong enough for a 1/8?

Her are my observations from 1/10 4WD...
I wish it was possible to do a true apples to apples comparison. Unfortunately, the nice smooth sensored motors run like crap on sensorless controllers. And noone that I know of makes a coreless sensored motor to see how it would run on the Novak ESC. I will admit the SS5800 system is not new, but they really have not changed that much. It is very smooth and rock steady from a dead stop. For parallel parking in my living room, the system is unbeatable. And in my 2WD truck like you are talking about, it is much easier to drive. In the 4WD though, I have put the hurt on a few novak powered B44's with the Mamba Max. There is one who keeps beating me, but it is all driver, not the motors. I think he is using an LRP Shpere with either a 6.5 or 7.5 motor. I think the motor was a Tekin but I could be wrong. One time after the race we swapped cars. He was totally shocked at how much more guts my car had. He didn't like my setup (too much push), and yet he still turned faster laps in my car than his own. He also had quick enough reactions that he had no trouble managing wheel spin so his corner exits were amazing. And of course the flip side, I was slower in his car than mine. Yes, in the slowest turns on the course, his was easier to place, and he had a little more steering in steady state, where the motor has NO effect. I have a little push dialed into mine because I am not as quick to respond as he is. Such is getting old. When the track was good, from the start tone, I pulled 6 feet on him into the first sweeper. Cogging is not an issue in a race.

I still feel a hybrid approach is the best. If sensors are available in the motor, use them for starting and even as a timing ref at speed, but have an ESC with enough processing to do dynamic timing advance. The Speed Passion GT does it, and I think the Losi Xcelorin Sensored does it as well. I think the Losi will only run sensored though, no sensorless mode. I would like it to be able to run in full sensorless mode for when the tiny sensor leads get yanked out of the motor in a minor hit on the truck.

And the reason sensored DOMINATES 1/10 is because only sensored motors are legal in big events, and like I said earlier, they don't run well on sensorless controllers. The new software in the Mamba Max does run them okay, but nothing like a good coreless motor, or a 4 pole like a Medusa or Neu. All the big sponsored drivers have deals with a sensored system supplier. The rules are very grey for a coreless motor in mod, but even there the rotor in the Mamba Max motors is way too big at over 18 mm. In the hands of a driver with the ability and reactions, the Mamba Max just plain flies on a track. It is far from a bash only system. It is not perfect, and neither are the Novaks. My lowly 5700 KV motor only revs like an 8.5R Novak but it cranks out more watts than a 5.5R by puming out way more torque.

This thread is about 1/8, and the buggies are all 4WD. I feel the 8 pound 4WD chassis can take the power of a solid 4S Sensorless system without the wheelspin issues of the 1/10 stuff. Here is the Novak spec chart
http://teamnovak.com/products/brushless/motor_spec_chart.htm
And it shows the issue I have with trying to make a 1000 1/8 setup. The 890 watt rated HV 4.5 has a KV of 5000 which ends up turning close to 70,000 rpm, about double a nitor motor so you will have a tough time gearing it right, and it is still way down on power from an average .21 nitro. It does have the much fatter torque curve, and great smoothness, so yes, it will be easy to drive, and on a very tight course it may do well. I am looking at a 2000 to 3000 KV motor to get nitro like rpms for proper gearing. The HV 7.5 is just down to 3000 KV and it is only rated at 620 watts. I feel that is not enough power for an 8 pound car trying to hit close to 40 mph. The Medusa 36x60 motors in the 2000 KV area will take more than 80 amps. At 14 volts that is 1120 watts. It should be an easy 1000 watts on a good 4S LiPo. I did the math on KT and all, and it will make over 1G of acceleration at less than 80 amps when geared to top out over 40 mph.

Now it is true that having too little torque to spin the tires is easy to drive, but it is not the fastest possible, but yes, it might be faster in poor conditions with a driver that can't react to the wheel spin.

This is still theoretical for me as I have not gotten my Medusa motor yet. I am looking forward to putting the numbers to the test. I have a few excellent 1/8 racers out here and I can't wait to see how it stacks up. I would have had a motor but I was talked out of the Feigao in favor of the Medusa, but I need to save up another couple weeks for it. It is not quite twice the price, but still nearly 1/2 a Neu. I can't wait to try it and report what I find.

[porra]

Just because you run a 6s setup doesn't mean that it is overpowered. If you use the appropriate motor and gearing, you gains are in terms of ESC loading. Higher voltage, less current = a happier esc. How many real hybrid automobiles do you see using a 12V system? None is the answer. Higher voltage is the way to go for efficiency and reliability. Running 4-pole and 6-pole sensorless motors is just like running a sensored 2-pole. Running my 6-pole mega on a Mamba Max, RS-Pro or Schulze U-force, I can't even tell it is sensorless.

HV is definetely the way to go. My MBX5T uses 8S lipos with my own 10S 120A ESC and it powers a 1515/2Y and I get MAX amp spikes of 60A. Here is a crappy video (2 part as it was 17min long) that I made to test a ESC for a client: http://www.youtube.com/watch?v=6RUtxc4-ZRQ, http://www.youtube.com/watch?v=kaH0ZdpP9Nc. I didn't charge my 2 4S 3700mAh packs before going out and I ran it at Trax70's off-road track with it for around 10 minutes.

[GSMnow]

Porra..
You were seeing 60 amp spikes, at 8S. That works out to a peak of 1680 watts, but what was the current holding at after the initial spike? I will bet the semi steady current was more like 30-35 amps. I only hold about 1/2 of peak. That is what I have been seeing on my 1/10 4WD. I see 80 amp spikes and hold just over 40 amps on 2S. How much does your car weigh? What are you geared for KV x volts MPH? My peak wattage of 560 watts is geared for just under 40 mph pushing 3.75 pounds. Pushing 8 pounds in my 1/8 conversion, I figure I will need about twice the wattage for the same speed. I am assuming you either weigh more or are geared faster than 40 to be seeing wattage that high. If not, I may have to adjust my numbers. I have not ordered my motor yet. Maybe the 36 x 60 Medusa on 4S will be too weak. I would love to see data logs on track.

[porra]

Porra..
You were seeing 60 amp spikes, at 8S. That works out to a peak of 1680 watts, but what was the current holding at after the initial spike? I will bet the semi steady current was more like 30-35 amps. I only hold about 1/2 of peak. That is what I have been seeing on my 1/10 4WD. I see 80 amp spikes and hold just over 40 amps on 2S. How much does your car weigh? What are you geared for KV x volts MPH? My peak wattage of 560 watts is geared for just under 40 mph pushing 3.75 pounds. Pushing 8 pounds in my 1/8 conversion, I figure I will need about twice the wattage for the same speed. I am assuming you either weigh more or are geared faster than 40 to be seeing wattage that high. If not, I may have to adjust my numbers. I have not ordered my motor yet. Maybe the 36 x 60 Medusa on 4S will be too weak. I would love to see data logs on track.

My MBX5T with the Mr. C. conversion and 8S lipos weigh around 8 pounds. Right now I have a 17T pinion and 48T spur (I usually have a 15T pinion, but only the 17T works with the finned Neu), so I'm geared for around 40mph. If you're going to use 4S you will see the high spikes, but when you go with a 8S and use a low Kv motor, you can really see the benefits and that will allow you to run smaller capacity packs to basically keep the same weight as using larger packs. I see people saying they run 30 minutes with 8000mAh (Sometimes more depending on how they gear) and I run that with only 3700mAh. Like I mentioned about 1000 times now with many people not aggreing with me, but here you go again: High voltage is the only way to go when racing 1/8 scale or larger vehicles. WHen I'm done with my TC3 chassis, I'll be running 4S 2200mAh in it with a low Kv sensored motor and you'll see that I can have a car as fast as one equiped with a 2.5T, but I'm going to be able to run cooler and longer.

[schenck77]

I am now returning to the electric 1/8th scale now that Novak has a great conversion kit that is the best on the market.

.


I also think you are dreaming or continue to have your blinders about everything novak makes. It has the orange case so it must be the best.:roll2:

The mount is good but only works with a novak motor. :mad: The brushless kit really needs to be updated though. I actually was excited when I first saw an hv pro listed online but that went away when I emailed novak and found out it was only an update to the current esc and not a new 6s esc that I was hoping for. There motors are also way to high of a kv rating.

With all that said I like novak's 10th scale motors a lot. However there 8th scale stuff is not there yet.

[SpEEdyBL]

I am now returning to the electric 1/8th scale now that Novak has a great conversion kit that is the best on the market.

ONLY the concept of being able to dissapate heat directly to the chassis is superior, but...

-You can only use novak hv motors.
-Novak motors are not ideal for 1/8 as you are limited to 9-12 tooth pinion gears in most setups, otherwise you get heat issues.
-Motor placement causes awkward mounting of electronics and batteries in some setups such as the 8ight.

[SpEEdyBL]

CRAPS..
I won't say the Novak is not a good system, it is smooth and trong. But are the HV's strong enough for a 1/8?

First to get a few things straight, Novak motors are rated with no load. A good rule of thumb is to multiply the no load kv by about .85 and that will get you the loaded kv for novak motors with proper gearing. The ss5800 you were comparing to btw, never actually had 5800 kv even with no load. I still don't know where novak came up with this number, but all their 8.5 turn motors are all rated at 5,000 kv w/ no load, and so was the ss5800 when the kv charts came out. Weird huh?

So back to the original question. Are the HV's strong enough for 1/8? I say yes, but like i said in the previous post, can only be used with small pinion gears such as 9 - 12 teeth, because of their high rpm/low torque design.

The novak hv 4.5 for example, is way overpowered for almost any track, and will outperform any nitro hands down. I actually just sent my hv 4.5 in to be exchanged with a 7.5 and have my fast motor be the castle neu 2650 motor, and gear higher or use 5s to compensate for the loss in kv. In fact, if you go over to the rctech.net forums, everyone has said that a 6.5 or 7.5 is either on par or faster than nitro, with much better acceleration.

My HV 4.5 could do wheelies in my 8ight, and maxamps 5000 cells weren't even up to the task when compared to my neu energy 4100 30c cells. Novak is right when they say the 4.5 is only good for short high speed runs. It's only usable for a full run when you use 9-10 tooth pinion gears on an open area.

Keep in mind that the power rating for novak motors a constant rating for a duration of 6 minutes. You only use 300 watts on average to get the typical 15 minutes out of a 14.8v 5000mah pack.

[Craps]

You guys can bash my simple Novak system all you want and you can quote those KVs and watts all you want because I am a racer and I see these overpowered systems that are totally useless for racing and making consitant lap times with that mattering most to me and not how fast I can knock the mail box down in front of my house with something that blows the tires off everytime you pull the trigger and tears the drive train up real fast.

This weekend was a good example that I finished 3rd in a 20 minute nitro race behind another Novak Conversion that finished a close 2nd behind a nitro buggy. There was those over powered systems in that race too that look great down the straight away, but are useless on the other 90% of the track where off road races are won.

My 7.5 motor went 20 minutes on a pair of 2S 6600 mahs Elite Batteries that had battery left over. No problem jumping everything with power to spare.

You guys that bash in the street knocking mail boxes over can keep on buying the over powered stuff. Not me! I am a racer!

[Ball Racing]

Get over this knocking mail boxes over thing

good grief

Oh, yeah chill,
remember you said you would play nice

I am not wanting this to be a bash thread, but an informative one for all to share info. With that being said, please race with whatever you are most comfortable with or even whatever you can afford.

Good luck to all!

[schenck77]

I never said the novak doesn't have enough power. I actually prefer my cars to be on the tamer side. The problem I have with them is the kv rating really doesn't give you much gearing options. Also the esc is outdated. Big and only supports up to 4s. Even on just 4s mine always ran way hotter then I would prefer.

[SpEEdyBL]

Craps,

Since you have posted in this thread, nobody here has bashed novak products, but you have bashed us as if you know a lot more about our setups and the intents of our setups than we do.

[kufman]

You guys can bash my simple Novak system all you want and you can quote those KVs and watts all you want because I am a racer and I see these overpowered systems that are totally useless for racing and making consitant lap times with that mattering most to me and not how fast I can knock the mail box down in front of my house with something that blows the tires off everytime you pull the trigger and tears the drive train up real fast.

This weekend was a good example that I finished 3rd in a 20 minute nitro race behind another Novak Conversion that finished a close 2nd behind a nitro buggy. There was those over powered systems in that race too that look great down the straight away, but are useless on the other 90% of the track where off road races are won.

My 7.5 motor went 20 minutes on a pair of 2S 6600 mahs Elite Batteries that had battery left over. No problem jumping everything with power to spare.

You guys that bash in the street knocking mail boxes over can keep on buying the over powered stuff. Not me! I am a racer!


I am not bashing the lack of power or the control, but I can't say that a conversion that limits you to one outdated motor system is the best on the market.

Out of curiosity (this is not an attack on you), how many were at your race last weekend? Up here in Illinois, we had about 30 turn out for 1/8th scale with 6 being electric. It was an unusual weekend because of the iHobby show. We had some out-of-towners at the race which made things interesting. I don't believe any of the electric buggies made the A, but I believe some of the electric truggies did. There were around 18 in truggy class with 3 being electric (I think). The track was a dust bowl which caused problems with the scoring printer... I think it is dead now. The track is built on a farm and the dirt is farm dirt, no clay. All of the corners are banked like a BMX track and the jumps are huge. There was a very interesting jump on the back stretch. It was a single into a table top into a second single. The table top had a jump on the end of it which could be used to jump over the second single jump that was after the table top. Tricky for all who drove no matter the power source.

[Craps]

I am not bashing the lack of power or the control, but I can't say that a conversion that limits you to one outdated motor system is the best on the market.

Out of curiosity (this is not an attack on you), how many were at your race last weekend? Up here in Illinois, we had about 30 turn out for 1/8th scale with 6 being electric. It was an unusual weekend because of the iHobby show. We had some out-of-towners at the race which made things interesting. I don't believe any of the electric buggies made the A, but I believe some of the electric truggies did. There were around 18 in truggy class with 3 being electric (I think). The track was a dust bowl which caused problems with the scoring printer... I think it is dead now. The track is built on a farm and the dirt is farm dirt, no clay. All of the corners are banked like a BMX track and the jumps are huge. There was a very interesting jump on the back stretch. It was a single into a table top into a second single. The table top had a jump on the end of it which could be used to jump over the second single jump that was after the table top. Tricky for all who drove no matter the power source.

There was over 20 1/8th scales with 4 of the electric. All 4 electrics were in the "A" main with the only 2 Novaks finishing 2nd and 3rd behind the gas one that won by less than 7 seconds about the time of a pit stop that was made to keep it fair. The electrics made 2 stops in 20 minutes and the gas guy made it on 1 stop at the 10 minute mark. This may change next week.

The other 2 electrics were of the non-sensored motor kind and were way overpowered making them difficult to drive with 1 of them not finishing the race. I will not mention the brands, but they are the kinds popular with the sensorless crowd.

It's not about how much power you have, but how you use the power you have by getting it hooked up to the track.

My Novak HV Pro with a Novak HV 7.5 has plenty of power to make every jump I want to make and gives me very consistant lap times.

Thank you Novak for doing your homework on the conversion kits!

PS. Hard to call sensored out dated when the sensorless came along first that the sensorless ESC has no clue on rotor position or the direction the rotor is turning. Give me sensored anyday for racing!

[kufman]

PS. Hard to call sensored out dated when the sensorless came along first that the sensorless ESC has no clue on rotor position or the direction the rotor is turning. Give me sensored anyday for racing!

Sensored motors were first on the market back in the 90's when Aveox started making them. The first sensorless I recall seeing was from Schulze, but that doesn't mean they were first. Tekin and Speed Passion now make hybrid ESC's that will use the sensors for startup and then switch to sensorless after that.
So far I am running very little power in my 1/8th. Just a Feigao 10L on either 12 NiMH's or a 3S lipo. I am hoping that Santa is allowed to ship Lipo in his sleigh... LOL!!! I have considered trying a Novak motor but I was hoping for something a little slower than the 7.5. I will run it on my Tekin RS Pro on something like 4 or 5S. I spoke with Bob at the iHobby show and he hinted that there might be a 4-pole motor in the future. I will keep my eyes open to all the products that are coming out this winter. I don't think I have seen anyone in this area run a Novak, but there might be a few at Leisure Hours this winter. The most common setups are Neu's, MMM's and a whole slew of different kinds and voltages of batteries. I need to sell some other stuff before I upgrade my RC8... or so the wife tells me, LOL!

[GSMnow]

The statement "overpowered" has a very different meaning to many people. My 1/10 truck with the Mamba Max was certainly overpowered, and with my skill level, it was tough to keep up with the better drivers, even when they were quite a bit sower down the long straight. But when I turned it over to a driver with fast enough reactions, the story was quite different. One driver was able to run laps with the best times of the day, even with my slow reaction friendly understeer setup. And he seriously complained my truck pushed like a pig, yet turned times good enough to TQ mod truck. How fast could he have gone with his setup on it?? I wish I had the data logger then. It was wild seeing him power it around without ever getting out of shape. I even questioned him abut the ESC and he had nothing but good things to say about the smoothness of control. Even to the point where he thought his 10 turn triple brushed setup has more punch at very low speeds, but the brushless just keeps pulling as revs climb, so it is much stronger above 20 mph. If geared correctly (and the right motor choice) the Mamba Max is a very smooth and well controlled system. Choosing the wrong motor and/or gearing it wrong can easilly make it much harder to drive but in my setup, it was proven to be a good amount of power for a highly skilled driver. Too bad my skills are no longer at the level. I left those reaction times about 10 years behind me. I drove an LRP powered truck with a 10.5 in it, and it was very fun to drive. I would love a bit more top end power, but down low it had just enough to get a tiny bit of wheelspin, but coming out of even the slowest turn on that track, I could just about slam the throttle full and the truck would hold it's line. At my skill level, I would like something in between. And that would be around a 7.5 turn ROAR setup. But that will have to run MOD and be up against people with the skill able to control a truck with the 5.5 in it. The Mamba Max 5700 is actually more powerful than even the 5.5R system, and it is plenty smooth, you just have less resolution because each 1/100th of an inch of trigger travel is a bigger change in power. Just because a system has sensors does not automatically make it smoother, slower, faster, better. I can not directly compare the Novak to a Mamba Max system. For my 1/10 I went with a Losi sensored setup for a few reasons. The big ones are the LiPo cutoff system, 3S LiPo operation, It cetainly does not run bad, but I don't think it is as smooth as the Mamba Max. Once my order of CC Bullets comes from Castle I will be trying the 13.5 motor on the Mamba Max. Good Luck, I hope all the electric guys start beating the nitros.

[kufman]

Craps,

What is your 1/8th geared at? What is the final drive of that buggy, 3.3:1?

[GSMnow]

My tank of a 1/8 conversion is going to be interesting and a bit heavy. I got my repaired Mamb aMax back, so now I just need the motor. I think I settled on the Medusa 36x60 2000KV. On 4S it should reach 28000 rpm. My fron tand rear diffs are 3:1 even, and the tires are stanbdard 1/8 buggy with about a 14 inch roll out. I want 40 mph capability, but wil start geared slower. I need 3000 rpm at the tires. 9000 rpm at the spur gear. That is just a 3.11 ratio from the pinion to spur. The standard Mod 1 spur for the car is 51 teeth. RC Monster carries from 10 to 25 tooth, so I am right in the middle I guess. They also have a 46 tooth spur. I guess I need to give my credit card a workout now.

[kufman]

My tank of a 1/8 conversion is going to be interesting and a bit heavy. I got my repaired Mamb aMax back, so now I just need the motor. I think I settled on the Medusa 36x60 2000KV. On 4S it should reach 28000 rpm. My fron tand rear diffs are 3:1 even, and the tires are stanbdard 1/8 buggy with about a 14 inch roll out. I want 40 mph capability, but wil start geared slower. I need 3000 rpm at the tires. 9000 rpm at the spur gear. That is just a 3.11 ratio from the pinion to spur. The standard Mod 1 spur for the car is 51 teeth. RC Monster carries from 10 to 25 tooth, so I am right in the middle I guess. They also have a 46 tooth spur. I guess I need to give my credit card a workout now.

LOL!! Mine is taking a breather for now. Going Lipo and 1/8th scale in less than 2 months was a bit of a load on it. It needs to rest up before X-mas arrives, lol!

[Craps]

We have around 15 E-1/8th Buggies here at the RC Pro Series Nats in Alavarado, Texas in the Diamond W Arena for a full "A" main for 2 exhibition races fro 15 minutes each with a motocross style start.

Monday was track building day.

http://i29.photobucket.com/albums/c264/Dice193/Electric%208th%20scale/1103081726.jpg

[GSMnow]

That looks very cool Craps. Can't wait to here how the race pans out. Try to get details on more of the cars to post, not just where the Novak powered ones finished.

I wonder if we could graft sensors onto a Neu 1512?? They would have to be just 60 degrees apart due to the 4 pole rotor. Of course, the 4 Pole Neus seems to run great sensorless so it is not a big deal. I will be trying my Sensored 13.5 motor on a Mamba Max as soon as my CC Bullet connectors show up. That will be in my 1/10 though. I need to wait for another check to order my Medusa motor for the 1/8 conversion.

[kufman]

That looks very cool Craps. Can't wait to here how the race pans out. Try to get details on more of the cars to post, not just where the Novak powered ones finished.

I wonder if we could graft sensors onto a Neu 1512?? They would have to be just 60 degrees apart due to the 4 pole rotor. Of course, the 4 Pole Neus seems to run great sensorless so it is not a big deal. I will be trying my Sensored 13.5 motor on a Mamba Max as soon as my CC Bullet connectors show up. That will be in my 1/10 though. I need to wait for another check to order my Medusa motor for the 1/8 conversion.

You would have to add little magnets on top of the rotor for the sensors to read. This is exactly how the old Aveox systems used to work.

[SpEEdyBL]

This is not the case with novak motors.

[Craps]

We were drag racing in the parking lot with a Caster Racing buggy with a Medusa motor in it against my Novak 7.5 and another Novak 6.5... I won with the Medusa 2nd.

[Ball Racing]

So you had better traction

[kufman]

This is not the case with novak motors.

With 2-pole rotors, the sensors can look directly at the main magnet. With 4-pole and above, the rotor is made out of stainless or aluminum and the magnets are secured onto that and usually wrapped in carbon or Kevlar.

[GSMnow]

If the rotor magnet extends out past the windings, then the hall sensors can directly sence it. But if the magnet of the rotor ends too close to the windings, then the hall sensors would get too much false magnetic signal from the windings and you could get poor timing accuracy or worse, it might just buck. So most industrial brushless motors have the separate pill magnets for the hall sensors, well away from the windings. Looking at the drawings of the Medusa motors, it would be a crap shoot. The windings are right to the edge of the rotor. The 2 pole coreless Mamba Max motors have the windings going well past both ends of the rotor magnet, so they would certainly have problems trying to put hall sensors right up to the rotor. My Losi Excelorin 13.5 motor has the hall sensors on a PC board sensing the end of the main rotor magnet. I found it very interesting that it has mechanical advance in the sensors for normal car rotation, even though the actual running timing is set at the ESC digitally. I can see this being a slight advantage as it is much easier to delay to retard the timing, but the ESC also has a reverse rotation mode, for use in the front of a Clod Buster for example. This makes it have to do much more advance ahead of the sensors to just get back to zero timing, let alone advancing it. I wonder if Losi (and the others) had to put the mechanical timing in the motor just to be compatible with the old ESC that could not do anything other than switch windings directly from the hall sensor signals??

Craps, as for your drag race... How controlled was it? Was there a traction limiting factor? How long was the run? Was there a point where the acceleration advantage changed (ie. the Novak got a jump but then the Medusa started to catch). What weere used for batteries and ESC's in both cases? Where everyones batts up to temp?

At my race last night, it was fairly cold out. It was obvious the LiPos were all soft for at least a lap or two. The 3 sensored B44's running 5.5 and 6.5 motors and my Mamba Max 5700 Losi XXX-4 were all geared for about the same top speed. I have my LVC set fairly high (6.4 volts) so for the first 2 laps, the sensored guys had a slight jump on my from low speed when the Mamba Max was going into current limiting to keep the LiPos above 6.4 volts. As of lap 5 or so, when I had another B44 right by me, I had a serious jump on him getting onto the straight. He was 8 feet ahead of me out of the sweeper, and had a better line, so he was on the power a good bit before me, but when I got into it, my car jumped in speed and closed the gap in a big hurry. I reached top speed, (about a matchj for him, when I got about 3 feet in front, and the we held that until the entry of the sweeper. I think his top speed was just a hair more, as he did inch up just as I had to lift for the curve. My car also was pushing a bit more, so I drifted up and took a wider line. After the 180 around a 30 foot radius, (I was 3 feet higher) we hit the double jump dead side by side. He had the inside for the 180 that followed, so he had a 3 foot lead out of it, but again, I was able to shoot up on him with the torque of the Mamba Max and I got the inside line on the 180 left hander.

I have now RACED my Losi Xcelorin sensored truck and my Mamba Max 4WD. I know the Losi is NOT a Novak. The Sensored sstem was easier to drive, but only because it is apple vs oranges. The 190 watt 13.5 spec motor is not in the same league as the low resistance coreless delta wound MM 5700 motor. But even with the greatly reduced torque, the sensored system was no "smoother" or any better at startup compared to the Mamba Max setup. I am actually able to creep around slower with the Mamba Max. The 13.5 even seems to have a "rubber trigger" feel where you need to over compensate with your finger to get what you want. In the tight infield, I found myself pulling a lot of trigger to get the car to accelerate, only to have to back off once it started to react. In most cases the torque was low enough, I could just jam full throttle, but if the track was dusty enough to wherer the wheels spun, it really took a big trigger drop before it re-grabbed and I could get back into the trigger. I really noticed this if I got a wide entry onto the straight and got off line onto the dust. My Mamba Max only needs a tiny blip lift for the tires to slow and re-grip the surface. The trigger input to torque ouput just seems faster and more solid on the Mamba Max.

I really want to do the apples to apples test. I will be running laps back to back with the Mamba Max ESC and the Xcelorin ESC. Both using the same 13.5 motor and LiPo pack in the same chassis, gearing, tires, etc. Hopefully I can borrow someone's 5.5 or 6.5 motor to also compare them at more power in the 4WD. Of course, I would love to try the Mamba Max motor on the sensored ESC, but it will certainly not be easy to add sensors to it.

The Medusa motor and the Novak motors are actually more similar to each other than the Mamba Max motors. Both the Novak and Medusa (and even Neu) use a steel lamination stator stack. This greatly increases the inductance which will cause more torque fall off with rpm, but in exchange, it has more torque for a given current and far less stray field since it is more focused into the rotor. This does yield higher max efficiency numbers with the trade off being a slightly narrower power band. Even as torque falls with revs though, the current falls as well so the efficiency holds up which results in a cooler running motor too. Only at very high rpm will the eddy current losses in the stator start to come into play. Pretty much any motor that can take over 1000 watts goes to a stator stack. The coreless winding stack in the Mamba Max (Feigoa, Hacker, etc.) has essentially no eddy current losses except for the can and/or flux band around it, and the lack of the stck in there allows for much more copper to be stuffed in. In my opinion, the lower resistance from the fatter wire for a given number of turns (KV) combined with the very low inductance is what makes the coreless motor have such extreme torque over a huge rpm range. In my truck, even at 30+ mph, the MM5700 still had the torque, to pull a wheelie from a roll. This same instant huge torque, is also to blame for it being harder to drive consistently on a tight course. Sensored or not, this instant extreme torque requires the finger reflexes of a ninja. The 4 pole stator design of the Medusa and Neu motors should be a pretty good median between the Novak and MM motors. Being 4 pole, the KV is cut down a lot, so the windings are far less turns, so the wirer can be very fat getting the resistance down. Of course, 4 pole is strictly illegal in 1/10 under ROAR.

[Craps]

A few pictures from the RC Pro Series Nats here in Texas!

Track Completed

http://i29.photobucket.com/albums/c264/Dice193/Electric%208th%20scale/1105081107.jpg

Driver's Stand

http://i29.photobucket.com/albums/c264/Dice193/Electric%208th%20scale/downsized_1105081109.jpg

Caster Racing's new E-1/8th

http://i29.photobucket.com/albums/c264/Dice193/Electric%208th%20scale/1104080853.jpg
http://i29.photobucket.com/albums/c264/Dice193/Electric%208th%20scale/1104080853a.jpg

[Caster Racing]

http://www.neobuggy.net/modules/news/article.php?storyid=5034

Newer Caster Racing e-1/8th.....

[porra]

http://www.neobuggy.net/modules/news/article.php?storyid=5034

Newer Caster Racing e-1/8th.....

That Hobbywing ESC looks good in there. It's a good thing what you're doing for 1/8 scale electric community.

http://i260.photobucket.com/albums/ii29/lutach/Hobbywing8thscalesystem.jpg

[Caster Racing]

It also looks amazingly like someone elses....We just chose to give credit where credit is due. If we make it, it has our name on it, otherwise, we are proud to let everyone know where it comes from. We will have some other interesting announcements in the next few weeks...exciting times for Caster Racing finally.

[porra]

It also looks amazingly like someone elses....We just chose to give credit where credit is due. If we make it, it has our name on it, otherwise, we are proud to let everyone know where it comes from. We will have some other interesting announcements in the next few weeks...exciting times for Caster Racing finally.

Looks good guys. Will everyone use 4S lipos or will they go with 6S to utilize the ESC to it's fullest?

[Caster Racing]

I know we will have 7.4 volt and 11.1 volt battery options....batteries will need to be wired in series......

So it will be both. 14.8 volts or 22.2 volts. I have personally only driven a sport with 14.8 maxamps batteries and it kept up with nitros perfectly with just a slight advantage. I think that 22 volts might be too much until the day comes when electric has its own class.

[GSMnow]

Which Medusa motor is that? I was thinking of the 36x60 2000KV, but I am starting to have some mixed feelings. At 4S the RPM is at the lower level of my gearing range, and I think 6S will be just too much power. I know what driving over powered is like, it is very tough to control, so I am back pedalling. I think I may go down to the 36x50 can, and go up a bit in KV for better gearing. Maybe the 3300 KV. This ends up being very close to the Novak 6.5 HV, and just a bit more than the 7.5 HV that Craps loves so much.

VS the 6.5.. 3300 to 3500 KV and 700 watts to 720 watts.
VS the 7.5.. 3300 to 3000 KV and 700 watts to 620 watts.

Will this poor 36x50 motor be overloaded? I will get it with the bonded heay sink if I go with it. On the flip side, I can always use it in a 1/10 since it is the standard 540 size. And it is cheaper too. Just $105.95 right now.

[porra]

I know we will have 7.4 volt and 11.1 volt battery options....batteries will need to be wired in series......

So it will be both. 14.8 volts or 22.2 volts. I have personally only driven a sport with 14.8 maxamps batteries and it kept up with nitros perfectly with just a slight advantage. I think that 22 volts might be too much until the day comes when electric has its own class.

You won't need to use the same Kv motor for 22.2 volts though. I run 8S lipos in my truggy with a 1515/2Y (1100Kv) motor and it's as fast or faster then a nitro, but I can get over 40 minutes of run time. Try running 22.2 volts with a 1500 or so Kv motor and you'll see some results. Are you guys still looking for drivers? I have a 200A sensored/sensorless ESC that I can use 4S lipos with and would like to have a buggy to try it on. Here is the thread about it if you want more information: http://www.radiocontrolzone.com/showthread.php?t=251978.

[GSMnow]

I just sent off an e-mail to Medusa to see if my numbers are right. From my math, I should see 1G acceleration at just 45 amps on 4S with the car geared for 40 mph and weighing in at 8 pounds. Surge currents will of course go higher, but the motor has a constant rating of 75 amps and a peak current of 90 amps for 30 seconds. If this really works out, I may have to try out one of their 28 mm motors for my 1/10 stuff.

[Caster Racing]

I personally run a 36x60x2000 Medusa.

Our new motor will be 36x60x2045. It is just a hair different.

[SpEEdyBL]

Stick with the 60mm cans. There's no way that a 50mm medusa will be able to keep as cool as a novak 6.5 or 7.5. The novak has 1.5 times the surface area and volume as a 50mm can and will disapate heat much better than the medusa.

[GSMnow]

When I first started this project, I figured a 60 mm can was the minimum, but I also started usngg numbers from Feigao, and I NEEDED an XL can to see safe constant heat disipation numbers. But when I started looking at the Medusa, the low internal resistance for a given KV rating just made the thermal disapation so much less. At 700 watts in, the Medusa is throwing off just 17.5 watts of heat off of the can, and it is rated to get rid of 40 watts constant on the small 50 mm can. The 60 mm can only increases the rated heat disipation to 45 watts, not a big difference at all when you figure n the internal resistance of the 2000 KV motor is still 0.006 ohms vs 0.007 ohms for the 3300 50 mm motor.

Porra...
If I was going with higher voltage, you are certainly correct. My 1/8 beast will weigh double my 1/10 4wd. With double the voltage, it will make double the power to move the double weight just as quick at just the same current. On a bigger track, or more open layout, I may want to gear a bit faster, but I just can't use any more speed locally. The 3300 motor is rated to 18 volts, so 5S is sorta in spec, but unloaded, it could exceed max rpm. 61,050 rpm at 18.5 volts. For a bigger track, the 60 mm 2000 or 2200 on 5S or 6S would certainly be able to be geared for more speed and still keep the over 1G acceleration potential. I have not recieved the reply from Medusa yet. I am very curious what they will say.

[porra]

Porra...
If I was going with higher voltage, you are certainly correct. My 1/8 beast will weigh double my 1/10 4wd. With double the voltage, it will make double the power to move the double weight just as quick at just the same current. On a bigger track, or more open layout, I may want to gear a bit faster, but I just can't use any more speed locally. The 3300 motor is rated to 18 volts, so 5S is sorta in spec, but unloaded, it could exceed max rpm. 61,050 rpm at 18.5 volts. For a bigger track, the 60 mm 2000 or 2200 on 5S or 6S would certainly be able to be geared for more speed and still keep the over 1G acceleration potential. I have not recieved the reply from Medusa yet. I am very curious what they will say.

I run 8S 3200-3700mAh packs in my trubby and it's light compared to the nitro version. You can still have this 1G accelaration even if you went with 6S and a 1500-1800Kv motor. You won't need large capacity cells and that's how you keep the weight down. You can lower you AMPs with a higher voltage and lower Kv, but you will have more torque and more efficiency than with the lower voltage/high Kv set up. I've seen my fare share of people using 6S with 2000Kv motor without success.

Edit: Here is a video of my truggy, I was testing one of my ESC for a client: http://www.youtube.com/watch?v=6RUtxc4-ZRQ, http://www.youtube.com/watch?v=kaH0ZdpP9Nc.

[GSMnow]

My intention is to have lower torque, basically just enough to break the tires loose, any more is just extra power I can't use. It is an experiment. If I go with the 50 mm can and it does not work out, I can always put it in a 1/10 and the KV at 3300 is just high enough to work on 2S, yet I could go to a 4S setup in a touring car and do blazing speed runs if I wanted.

Going to the 60 mm meduse, certainly makes more power, and torque everywhere. The problem i am running into is when the internal resistance is too low, the torque is to abrupt when you increase throttle. The perfect solution would be an ESC that is more like an engine throttle. In a real car, you push the throttle down, and you get more torque, and then as revs climb, the torque falls back down until it matched the drag needed to maintain speed. Old brush motors were pretty close to this because they had a fair amount of internal resistance. The current would increase and fall away fairly smooth based on the difference of the command voltage from the ESC and the back EMF generated by the motor. With a low internal resistance motor, this is not a smooth slope, but almost a vertical step.

Using even the 0.007 of the 50 mm motor, look what happens.
On a 4S system with the 3300 kv motor. You are rolling at 1/2 throttle, giving the motor 7.4 volts and it is turning at 24,000 rpm and pulling just 8 to 9 amps to maintain 20 mph. Now you get the the end of the sweeper, and pull just 1/8 more trigger for 5/8 of 14.8 volts. The is a tiny trigger movement. This ups the ESC output to 9.25 volts, but the motor is still only turning at 24,000 at the moment, so the back EMF voltage is 7.27 volts. At half trigger, it was only 9 amps with a voltage difference of 7.4 - 7.27 or 0.13 volts. This works out to a total resistance of 0.014 ohms, so the battery, wire, and esc adds about the same 0.007 as the motor itself. These numbers are very close to what I have been getting with the MM5700 setup in my 1/10 buggy. Witht he 5/8 throttle, just a 1/8 pull from 20 mph cruise we now have a voltage diference of 9.25 - 7.27 = 1.98 volts accross that same 0.014 ohms. 1.98 / 0.014 = 141.4 AMPS!!!! This results in huge wheel spin with almost no trigger movement. In reallity, the current is a little softer, and due to the wheels spin it never reaches that high, but I have seen 80 amps on my 4WD buggy many times as the wheels break loose and the current falls to 40 amps as the car is in a drift with the wheels spinning. I want to find a way to make the current increase less, and still reach the desired voltage. So far my only semi success had been adding some resistance. This throws away power to heat, not ideal. But from my testing, I know I want a motor with no less than 0.006 ohms. Lower KV motors do tend to have more resistance, but running at higher voltage again gives the huge torque increase. running at 29.6 volts (8S), a 1/8 increase in throttle is a full cell (3.7 volts). Even with a very high 0.017 ohm motor (Medusa 36x60 1000 KV) and a high .01 ohms for the wire and ESC for a total of .027 ohms,the current increase is huge. That works out to 3.7 / 0.027 = 137 amps. And that can happen at any point in the throttle, from a dead stop to 3/4 to 7/8 throttle. And that 137 amps at the higher voltage is even more wattage increase. Yes, high voltage will make a ton more power and is more efficient, but I see it making this touch throttle problem even worse. I tried a 3S powered 1/18th truck and saw the same issue. Going 2S with a bigger pinion was far easier to control.

Of course the idea solution would be a device to measure current and then control the pulses to the ESC to control torque. The problem so far is latency and overshoot. It would work much better if the current limiting control was designed right into the MCU that is already taking the RX pulses and driving the FET's. There have been a few curre nt imiting ESC's, mostly for brushed, but a few for brushless as well.

[porra]

You know that all this math you keep doing doesn't add up in real life you know. I have done many trial and error through out my 14 or so years messing with brushless. I tired everything there is to try and seen many numbers, but none of them made much sense and it takes a while to get the right set up done correct. The Medusa 50mm motor will do fine in your buggy. If you plan on using 4S lipos, go with the 2200Kv model and you'll keep the motor just above the sweet 30000rpm range which will give you a nice and efficient set up for your voltage. If you use a 51T spur, you will find that a 14T pinion will be just right. Most ESCs made for car will give you a lot of torque at start up and that's where you'll see the most AMP spikes and after the vehicle gets rolling you won't see those big spikes. I've seen all the math and they don't do anything in real life. With my 8S 3700mAh, Neu 1515/2Y I got over 40 minutes of run time. I had all the speed I needed and all the torque to pop wheelies on dirt.

[porra]

running at 29.6 volts (8S), a 1/8 increase in throttle is a full cell (3.7 volts). Even with a very high 0.017 ohm motor (Medusa 36x60 1000 KV) and a high .01 ohms for the wire and ESC for a total of .027 ohms,the current increase is huge. That works out to 3.7 / 0.027 = 137 amps. And that can happen at any point in the throttle, from a dead stop to 3/4 to 7/8 throttle. And that 137 amps at the higher voltage is even more wattage increase.

This is completely wrong. I've seen maximum of 60A spikes from my 8S set up. All this math will do is keep you from running a good set up when you actually think it's bad.

[SpEEdyBL]

The best solution to preventing wheelspin imo is just to run nimh. Motors do not like to spend a lot of time at the low end of their rpm range, otherwise they heat up. In fact all motors are 0% efficient at 0 rpm, and their efficiency goes up as rpm increases until somewhere near peak rpm (motors are also 0% efficient at peak rpm).

The lack of wheelspin that you are aiming for translates into a longer time when the motor is barely spinning, and that translates into more motor heat.

By using ni-mh's over lipo, you are effectively increasing the resistance of the entire circut (battery, esc, motor) without increasing the resistance of the motor. The lower resistance of the motor, the less heat created by the windings.

Example:

Two eqivalent setups are:
1. A motor with .005 ohms of resistance and a 15 volt battery of .035 ohms
2. A motor with .010 ohms of resistance and a 15 volt battery of .030 ohms

With both setups, you will get a maximum possible amp draw of 375 amps (15/.04, but with setup 1, you will get 1/2 the heat in the motor due to copper loss and only 20% more heat in the battery.

[GSMnow]

Porra...
You are correct that we NEVER see the calculated current spike numbers. The reason is because something is letting go and acting as a limiter. The problem I am seeing is that the limiter is the motor rpm jumping up and spinning the tires, even just 10% wheelspin will greatly drop the actual current down, but at the same time, the car is skating over the surface. My Mamba Max 5700 Losi XXX-4 buggy is doing this for a good chunk of the lap. I have the data logs to prove it, and the fatigued finger trying to control it. My power is second to none on the course, it is just hard to drive ecause the slightest blip of the throttle can cause near instant wheel slippage over the ground. In my particular setup, it take 40 amps when the wheels are spinning free of the ground. Any less current and I have grip to steer, but any more only lasts until the tires break loose. This equates to 280 watts in my 3.6 pound 4WD buggy. Your 8S 3200 setup running for 40 minutes works out to a constant current of just 4.8 amps, but even that is 142 watts. And your 60 amps peaks on 8S are an insane 1776 watts. I bet you sustain something like 20 amps as the tires are skating like mine. 20 amps x 28 volts is 560 watts, or double my 280 watts of 40 amps on 2S in a car about 1/2 the weight.

I don't doubt your setup works well and puts out a ton of power. I was tempted to go high voltage, but as you increase voltage, the resistance apears to reduce as a percentage of true power. This is great for efficiency and will certainly give the longest runs. Too bad it seems to also cause the trigger to lose all feel as the torque from a small trigger move is just too much. My data logs show the current hitting the wheel spin limit almost every time I pull the trigger.

Speedy...
At any given speed and trigger position, your math about the battery resistance doing the same thing as motor resistance is true, but only at near full trigger. I experimented a bit with adding resistance in both battery and motor leads, and I found a big difference in how it reacted depending on speed and trigger position. With a resistor in series with the battery, it still would blaze the tires at low speed very easilly, but it got very pokey with no torque when the speed came up. Adding 3 resistors in the motor wires softened the torque much more evenly across a very wide rpm range. At low throttle settings, the ESC is doing PWM at high frequency using the motor coil to store energy. This causes the motor winding to actually see more current than the battery lead, but at a lower voltage. Basic switching power supplies use this principal to regulate voltages down very efficiently by trading voltage for current. At full throttle, this sorta falls apart as the FET's go to near full on for each phase. The only switching being from phase to phase which is too low of a frequency for the tiny inductance of the motor to store much power.

To both of you (and others reading along) YES!!!! resistance is bad for efficiency and maximum power. We have reached the point where we have all the power we can use on the track. My goal now is to make that power easier to drive. With the MM5700 in my 2WD stadium truck, it was almost comical how easy it was to just pull the front tires right into the air. Even rolling at 20 to 3 mph, I just had to jerk the trigger a little and the front went air born. And that is a XXX-T MF2 with a very low CG. I spent a year trying to figure out how to drive the MM5700 to it's limit, but I still find it just too touchy for a critical lap. The 13.5 motor in my truck now is EASY to drive and I can slam the throttle all over the place. Wheelspin is rarely an issue. At low speed and a huge throttle pull,it will suck over 50 amps, but due to the internal resistance of that motor, it takes a huge yank of the triger to pull enough current for the motor out torque the tires.

For 1/10 I need a motor between the MM5700 and the 13.5, obviously. I still hope to try the 13.5 motor onthe Mamba Max esc, I just have not had any time.

[marinearmeni]

@ GSMnow
Have you had a look at the Tekno RC conversion kits? They utilize a clutch and mechanical brakes like a nitro. I can tell you from experience that the clutch makes the power of the brushless system usable on the track. It still has way more power and acceleration then nitros but you can use it.
Here's some vids.
This one is me running a 50mm Medusa 2200 on 4s through a MM
http://www.youtube.com/watch?v=cYsq4M_o8PI
These two are part 1 and 2 of my truggy race. I'm running either a 60mm Medusa 1300 or a Neu 1515 1.5Y on 6s through a MM.
http://www.youtube.com/watch?v=IHpjZ8f85Pw
http://www.youtube.com/watch?v=NTdA28m9wAE&feature=related
And this one is the owner of Tekno RC during a qualifier, Neu 1515 3D on 6S through a MMM.
http://www.youtube.com/watch?v=dLa6dF82SC0&feature=related
Besides my buggy, everything else was running 6S and the power is definitely usable.

[porra]

Porra...
You are correct that we NEVER see the calculated current spike numbers. The reason is because something is letting go and acting as a limiter. The problem I am seeing is that the limiter is the motor rpm jumping up and spinning the tires, even just 10% wheelspin will greatly drop the actual current down, but at the same time, the car is skating over the surface. My Mamba Max 5700 Losi XXX-4 buggy is doing this for a good chunk of the lap. I have the data logs to prove it, and the fatigued finger trying to control it. My power is second to none on the course, it is just hard to drive ecause the slightest blip of the throttle can cause near instant wheel slippage over the ground. In my particular setup, it take 40 amps when the wheels are spinning free of the ground. Any less current and I have grip to steer, but any more only lasts until the tires break loose. This equates to 280 watts in my 3.6 pound 4WD buggy. Your 8S 3200 setup running for 40 minutes works out to a constant current of just 4.8 amps, but even that is 142 watts. And your 60 amps peaks on 8S are an insane 1776 watts. I bet you sustain something like 20 amps as the tires are skating like mine. 20 amps x 28 volts is 560 watts, or double my 280 watts of 40 amps on 2S in a car about 1/2 the weight.

You might have to mess with your slipper a bit to get the power to the ground. I don't have a XXX-4, but from the ones I've seen it looks like it has a slipper clutch. Isn't the punch control on the Mambas supposed to help with this situation? Other thing you can do is mess with the throttle curve.

[porra]

GSMnow,

Just another suggestion. Have you thought about just using a lower Kv motor?

[Craps]

Maybe the 3300 KV. This ends up being very close to the Novak 6.5 HV, and just a bit more than the 7.5 HV that Craps loves so much.

VS the 6.5.. 3300 to 3500 KV and 700 watts to 720 watts.
VS the 7.5.. 3300 to 3000 KV and 700 watts to 620 watts.



Actually I am urging Novak to come out with an HV 10.5 motor that will be around 2000 KV with around 480 to 500 watts.

[kufman]

Actually I am urging Novak to come out with an HV 10.5 motor that will be around 2000 KV with around 480 to 500 watts.

That would be more useful in terms of 1/8th scale buggies.

What ever happened to that big race that was going to have some 1/8th electrics? Did that already take place?

[ta_man]

Using even the 0.007 of the 50 mm motor, look what happens.
On a 4S system with the 3300 kv motor. You are rolling at 1/2 throttle, giving the motor 7.4 volts and it is turning at 24,000 rpm and pulling just 8 to 9 amps to maintain 20 mph. Now you get the the end of the sweeper, and pull just 1/8 more trigger for 5/8 of 14.8 volts. The is a tiny trigger movement. This ups the ESC output to 9.25 volts, but the motor is still only turning at 24,000 at the moment, so the back EMF voltage is 7.27 volts. At half trigger, it was only 9 amps with a voltage difference of 7.4 - 7.27 or 0.13 volts. This works out to a total resistance of 0.014 ohms, so the battery, wire, and esc adds about the same 0.007 as the motor itself. These numbers are very close to what I have been getting with the MM5700 setup in my 1/10 buggy. Witht he 5/8 throttle, just a 1/8 pull from 20 mph cruise we now have a voltage diference of 9.25 - 7.27 = 1.98 volts accross that same 0.014 ohms. 1.98 / 0.014 = 141.4 AMPS!!!! This results in huge wheel spin with almost no trigger movement. In reallity, the current is a little softer, and due to the wheels spin it never reaches that high, but I have seen 80 amps on my 4WD buggy many times as the wheels break loose and the current falls to 40 amps as the car is in a drift with the wheels spinning. I want to find a way to make the current increase less, and still reach the desired voltage. So far my only semi success had been adding some resistance. This throws away power to heat, not ideal. But from my testing, I know I want a motor with no less than 0.006 ohms. Lower KV motors do tend to have more resistance, but running at higher voltage again gives the huge torque increase. running at 29.6 volts (8S), a 1/8 increase in throttle is a full cell (3.7 volts). Even with a very high 0.017 ohm motor (Medusa 36x60 1000 KV) and a high .01 ohms for the wire and ESC for a total of .027 ohms,the current increase is huge. That works out to 3.7 / 0.027 = 137 amps. And that can happen at any point in the throttle, from a dead stop to 3/4 to 7/8 throttle. And that 137 amps at the higher voltage is even more wattage increase. Yes, high voltage will make a ton more power and is more efficient, but I see it making this touch throttle problem even worse. I tried a 3S powered 1/18th truck and saw the same issue. Going 2S with a bigger pinion was far easier to control.
As someone noted, the math is keeping you from a better system.

I've read many of your other posts and it appears these calculations are similar to ones you have done on your Mamba Max/5700 system that led you to try the series resistance to soften the 5700.

I believe the factor you are neglecting, that is leading to calculated results that don't jive with other people's realities, is that you are now dealing with slotted motors that have significant inductance. Because of that inductance, the amp draw can't spike according to your calculations based simply on resistance.

It just doesn't happen in real life with these motors/cars that 1/8 throttle increase gives you tremendous wheelspin.

[Craps]

That would be more useful in terms of 1/8th scale buggies.

What ever happened to that big race that was going to have some 1/8th electrics? Did that already take place?

Had a full main of them start at the RC Pro Series Nats in Texas and only 2 finished with one of those dumping in a 15 minute main. It was a disaster for an exhibition class that was to showcase the class.

Oh well! We have around 10 of them commited to race at the Farm this weekend where the 1/8th scale buggy worlds was at a couple of months ago and the Fall Brawl at Myrtle Beach, SC has 10 already signed up for it there on December 6th and 7th. Maybe Ryan Maifield who is suppose to race there will bring the new E-RC8 they are working on.

Then there is the J-Concepts race in Florida on December 13th that has a class of E-1/8th scales that Ryan is suppose to be there too.

[porra]

Then there is the J-Concepts race in Florida on December 13th that has a class of E-1/8th scales that Ryan is suppose to be there too.

That place in Florida is where I used to race on-road. It's a very nice location and you should go there.

[GSMnow]

As I wrote before.... Yes, the current will not spike as high as the resistance alone suggests. There are two main reasons for that. The inductance is real, but very small and only slows the current built up a few milliseconds. Even the slotted motors are low, especially when it is just 4 turns per pole. I am hoping the inductance will help some, but I am not betting on it. In fact the current lag from the inductance is how PWM control of the motor current works at all, and it is done at a couple thousand hz. The RC control frame rate is just 50 to 60 hz on most transmitters, and only 120 hz on the latest Futaba FASST systems. So if the TX asks for more current, and it builds up to the point of wheel spin, you can't even correct for it for 1/50 of a second, and the current build up took just 3/1000 of a second due to inductance. The Mamba Max punch control slows the throttle rate to something like 0-100% in 1 second or so depending on setting, too bad it always does that, even when in the air off of a jump.

The big reason the current does not fully spike in my case is almost all from the slipper clutch and wheel spin allowing the motor rpm to come up far enough so that the effective voltage difference is less, and then the current to resistance formula is actually correct again. The theoretical 120 amp jump is only reaching about 60 amps when the tires break loose and spin. This let's the revs up a tick more and the current falls to just 40 amps. If I hold the car back and firmly to the ground, I do see over 80 amps, and I did catch spikes close to 100 amps, but then the Mamba Max cut into LVC as the batery voltage fell below 6.0 volts. The effective series resistance also appears to raise with current. At low current my low calculates to 0.015 ohms, but at 50 amps, it looked more like 0.025 ohms. I think that is the battery and/or FET heating.

I do also want to try a lower KV motor with taller gearing. In theory, when geared for the same top speed, the available torque for a given batter current will be virtually the same, but the higher KV motor has (MORE SERIES RESISTANCE) which should do exactly what I want. Noone around me stocks a MM4600 motor, or I would have tried one by now. I also want to try the Medusa 3300 50 mm in my XXX-4. I should be able to get the right pinion for it. I will need a 48 pitch around 29 teeth, and I can go smaller if I change the spur down from the 94 in there now. The Medusa has the same series R as the MM5700 motor though, so I expect about the same torque punch.

My series R experiment worked well. I liked the feel, but it caused other issues. Trying to get a low enough R with perfect balance on the 3 leads was not easy, and the heat and weight was just manageable in the truck, and won't fit at all in the 4WD buggy.

[ta_man]

As I wrote before.... Yes, the current will not spike as high as the resistance alone suggests. There are two main reasons for that. The inductance is real, but very small and only slows the current built up a few milliseconds. Even the slotted motors are low, especially when it is just 4 turns per pole. I am hoping the inductance will help some, but I am not betting on it. In fact the current lag from the inductance is how PWM control of the motor current works at all, and it is done at a couple thousand hz. The RC control frame rate is just 50 to 60 hz on most transmitters, and only 120 hz on the latest Futaba FASST systems. So if the TX asks for more current, and it builds up to the point of wheel spin, you can't even correct for it for 1/50 of a second, and the current build up took just 3/1000 of a second due to inductance.
I don't know what the actual inductance is but since people don't get the wheelspin (with the slotted motors used in most 1/8th scale conversions) that your calculations suggest they will, the inductance (or some other factor) is obviously large enough to have an effect.

You suggest the inductance will slow the current build up for a few milliseconds. That is more than enough to be a significant effect:

Take a motor RPM of 18,000 (2000KV at 9V - close to your example). That is 300 rev/sec (18000/60). So each revolution is 3.333 ms. I'm not sure about current switching in a 2 pole motor - it's either 3 or 6 times per rev, but lets say 3 times. So each on pulse for one coil is only 1.111MS long (assuming you just went to full throttle). If the inductance can delay current build-up for a "few" ms, that's more than enough to reduce it for a 1.111MS pulse for each coil.

PWM frame rate does not appear to be relevant.

[porra]

One thing I have learned early in the game with electric is if you want to prevent wheel spin, throttle control is your best friend. I used to race karts in Brasil and had a lead foot, but RCs are different and I had to learn how to keep the lead off my trigger finger lol. It's still awesome to punch it though lol.

[kufman]

Had a full main of them start at the RC Pro Series Nats in Texas and only 2 finished with one of those dumping in a 15 minute main. It was a disaster for an exhibition class that was to showcase the class.

Oh well! We have around 10 of them commited to race at the Farm this weekend where the 1/8th scale buggy worlds was at a couple of months ago and the Fall Brawl at Myrtle Beach, SC has 10 already signed up for it there on December 6th and 7th. Maybe Ryan Maifield who is suppose to race there will bring the new E-RC8 they are working on.

Then there is the J-Concepts race in Florida on December 13th that has a class of E-1/8th scales that Ryan is suppose to be there too.

Ouch!! Well, I guess things can only get better next time. What was the guy running that dumped in less than 15 min?

[GSMnow]

The inductance of my 13.5 turn Losi motor is 19.2 micro henries. I had to look up the formula to make sure this was right.
dI/dT=V/L This will show how little time it takes to charge such a tiny inductance. 19.2 micros henries is 0.0000192
change in current in one second = voltage/inductance
(delta I over 1 second) = (1 volt change / 0.0000192)
applying just one volt across the coil, a perfect inductor with no resistance would have the current ramp to 52,083 AMPS in just one second. In 1 millisecond, that is still 52 amps, and this is the iron core 13.5 with a KV of just 2500. At 1 volt it would only be turning 2500 rpm 42 turns per second. Each coil is on 1/3 of a turn. (1/42)/3 = 0.008 seconds, or 8 milliseconds. With the current building at 52 amps per millisecond, you get 416 amps! in 1/3 of a revolution. If you jack the voltage to 7 volts, you will find the same current at 1/3 revolution because the increase in current ramp up rate will match the rpm increase.

Basically, the DC resistance will have a much bigger effect on the max current. My 13.5 motor has a measured DC R of about 0.039 ohms. 1 volt across that works out to just 26 amps. Smaking the coil's DCR with 7 volts will make 180 amps, thanks to the inductance, it will take just under 1/2 millisecond to reach that. I should have used micro instead of milli when I posted about the charge time of the inductance. I have an LCR bridge burried around here somewhere. I will have to dig it out and get some real numbers on other motors.

I wish my finger was good enough to control the wheel spin. Sadly, it is not. My 42 year old reactions are not as fast as the teens and 20's I run against every week. And this does explain why a driver who trophied the Worlds can rip a faster lap than me, driving my own car. What I am trying to achieve is make the car easier to hold at the limits of grip, but it should still be able to exceed the grip which means it should be as fast as a car with unlimited power. The difference will be a more forgiving trigger. With my Mamba Max 5700 in the 2WD truck, a 1/8 travel blip was typically enough to spin the tires out of a corner. It has to be rolled on at exactly the same speed the truck accelerates across the ground. Any slower and you are not as fast as you could be, and any quicker and the tires either spin losing rear grip, or it does a wheelie and you can't steer, or it goes all the way over and lands on it's roof sliding backwards. My goal is to make the trigger feel more like a nitro throttle but without lag. I would like to get a solid 1/4 travel past current speed without spinning the tires. If I am at 20 mph (1/2 trigger), and pull to 3/4 trigger, I want it to pull 40 amps with rising voltage and falling current until the wheel speed is at 30 mph and the current rolls down until steady state at about 9 amps. So each 1/4 of trigger would mean 40 amps. From a dead stop that still commands 160 amps, so you still need to modulate some. To do this with just resistance would mean 0.046 ohms total from the battery cells to the windings. That is about triple what I have in the 4WD 1/10 buggy. The 4S 1/8 setup would need twice as much, so it is totally not practical. 0.046 ohms at just 40 amps would be a serious 74 watts of heat. That is basically a big soldering iron. That is why my series R experiment ended. It worked, I turned my fastest laps with it in the truck.

[ta_man]

Well, the inductance on the Neu motor in my Losi 8ight electric conversion measured at 9 micro henries, I run 5000 mAHr batteries rated at 28C (140 amps continuous) and I'm pretty sure my 58 year old reaction time is way worse than yours (I can't even think about trying to do mid-air corrections). With all that, I have no trouble with wheel spin or too much torque.

But if your calculations tell you a 50MM motor will be easier to drive than the 60MM, get the 50.

[kufman]

GSmnow,

Here is a simulation of your equations. I added some resistances for wire, esc, and battery. The voltage pulse is 7.4V high and 2ms long. Your math is close, but it assumes that the V= L*dt/dt is linear forever, which it isn't.

Circuit
http://kufman.com/img/rc/motor_simulation/motor%20circuit.JPG

Graph
http://kufman.com/img/rc/motor_simulation/motor%20circuit%20output.JPG

[kufman]

The other thing I forgot to mention is the effects of Eddy Currents and Core Saturation. The Eddy currents in the steel will oppose the applied field. I don't know how much of this there is, but it will have an effect. If the core saturates, the inductance is falling off so the di/dt will be much higher, but the field will not be getting stronger. I hope to have test setup soon that can look at these things. I have power supplies here at work that will laugh at the power required to run these motors. :-)

[porra]

Well, the inductance on the Neu motor in my Losi 8ight electric conversion measured at 9 micro henries, I run 5000 mAHr batteries rated at 28C (140 amps continuous) and I'm pretty sure my 58 year old reaction time is way worse than yours (I can't even think about trying to do mid-air corrections). With all that, I have no trouble with wheel spin or too much torque.

But if your calculations tell you a 50MM motor will be easier to drive than the 60MM, get the 50.

ta_man,

That can't be your real age. When I met you at Dirt Runners, I was under the impression you were around 40. Man, I want to look that young when I'm 58 too. I also want to drive like you at that age.

Regards,

Luciano (lutach in other forums).

[SpEEdyBL]

GSMnow, have you ever played around with the LVC on the Mamba max to reduce punch? For 2s, try setting it to something high like 6.8 volts. In theory this acts as a current limiter and reduces the throttle to keep the voltage above the limit.

[GSMnow]

Yes, I did use LVC like that. It worked great on the nickle batteries. Set at 5 volts is was nice to drive, but too soggy some times. With my weaker LiPo's (20C 3000) having it at 6.6 volts was a dog when they were cold, but then it ran well when the pack got hot. With my new 20C 5000's it still has rock solid wheel spinning torque with the LVC upto 6.8 volts. Looking at the data logs, I see why. Those packs hold over 7 volts to 60 amps and the wheels spin at 40 to 60 amps, depending on surface condition.

When I am ON I can turn a few good laps without blowing it. At the last event with the MM5700 set for full torque, no punch, LVC at 6.0 etc. I turned 4 laps within 2/10's of the fastest guys there. The problem was I am just not as consistent as them, because one tiny slip with the trigger, and I have to make big corrections. The car is just not forgiving at all because of the huge torque. On the old layout I dialed in more push as a band aid, but on the new layout I didn't have enough steering and had to make the car more responsive. And that made the throttle just too easy to get it out of shape.

In the bigger, heavier 1/8 buggy, it should react slower to everything I do, and the current spike from the throttle should be more manageable. I just want to start with something that won't overwhelm my ability. The 50mm vs 60 mm motor is a very tough choice. The price is very close, and not a concern. On 4S I can gear either for the speed range I need. The 50mm will fit in my XXX-4 and can gear to work in there on just 2S, and it may also be the ideal motor for the 2WD truck. The Medusa 3300 4 pole should run close to the Vellineon 3500, but more efficient for longer runs and lower temps. The VXL's do run well on our track. A few people have even put a VXL motor on their Mamba Max ESC for the lower KV to make it easier to drive. My local track will let me run the 4 pole motors for club races, but not sanctioned events. The dual (maybe triple) use of the 50mm 3300 makes it a compelling choice. The 60mm would be a dedicated 1/8 motor. If the 50 mm proves too slow, I can always move up.

I am trying to be open minded, but I know this looks like I already made up my mind and I am not listening. That is not the case. I appreciate all the advice and comments.

[porra]

GSMnow,

If you really want something that controls the throttle limit amount, please look here:

http://www.radiocontrolzone.com/showthread.php?p=2374567&posted=1#post2374567

You can fine tune the percent of throttle you need in the ESC via the program box option 6.

[chewie]

With my e rc8 running a neu 1512 1.5d/f. In air correctioons were a handful until I turned the braking down. I finally got a new pack and this motor is NUTS.

[ta_man]

In the bigger, heavier 1/8 buggy, it should react slower to everything I do, and the current spike from the throttle should be more manageable. I just want to start with something that won't overwhelm my ability. The 50mm vs 60 mm motor is a very tough choice. The price is very close, and not a concern. On 4S I can gear either for the speed range I need. The 50mm will fit in my XXX-4 and can gear to work in there on just 2S, and it may also be the ideal motor for the 2WD truck. The Medusa 3300 4 pole should run close to the Vellineon 3500, but more efficient for longer runs and lower temps. The VXL's do run well on our track. A few people have even put a VXL motor on their Mamba Max ESC for the lower KV to make it easier to drive. My local track will let me run the 4 pole motors for club races, but not sanctioned events. The dual (maybe triple) use of the 50mm 3300 makes it a compelling choice. The 60mm would be a dedicated 1/8 motor. If the 50 mm proves too slow, I can always move up.

I am trying to be open minded, but I know this looks like I already made up my mind and I am not listening. That is not the case. I appreciate all the advice and comments.

Just a FYI.

I don't know how the Medusa motors compare directly to the NEUs but a number of guys apparently tried the Neu 1509 motors in 1/8th conversions, figuring they were lighter and could run on 3S to reduce the overall running weight. The sum of the experience was that the 1509s just don't have enough power and heat dissipation capability to do the job under adverse circumstances (like warm weather). Just not enough headroom with the smaller motor. No one at RCTech has even considered a 50MM Medusa for this application.

[chewie]

I had mentioned the medusa motors but only a couple tried them. Ill stick to my neeu though but if I were to do it over instead of buying a feiago id get a medusa

[SpEEdyBL]

I think there were a few people on the rcm forums who have tried the medusa 50mm in 1/8 with success, and there were definately some who have tried the neu 1509 motors with success. You would assume peak efficiency for all 15 series neu motors would be roughly the same, so a neu motor 3/4 the size of another neu motor, would be able to make 3/4 the power.

Say you want 3/4 the power of your 1512 1.5y. The solution is to get a 1509 2Y, which has about the same kv. If it is in fact 3/4 as powerful AND you actually try to use 3/4 the power by staying the same on the throttle as you did before, it will create 3/4 the heat, so no increase in temperature.

If anybody is having heat problems with a smaller motor, they are probably trying to gear for the same speed as the bigger motor, with the intention to have less torque. Please note that you CANNOT get the same speed in the same amount of time with less torque, without changing anything else. The smaller motor has to spend more time drawing power in order to get to a given speed, and the longer a motor spends before it has topped out, the more it will heat up. The solution? Gear lower by about the square root of the ratio of sizes. Overall acceleration will still be slower, but it will take the same amount of time for the motor to top out.

GSMnow, I am starting to like your idea of the 50mm medusa motor in 1/8. I don't see why you wouldn't be able to slap a big heatsink on it to have it dissappate heat just as well as a bigger motor. As long as a motor is geared so that it can spool up quickly enough, it is not going to care whether it is in a tank or a go-cart. Temps should be the same. FYI you would probably need to gear with 9-10 tooth pinion gears if you went with the 3300 kv version in a 1/8 buggy, which is why I would still recommend a lower kv. What it all comes down to are these two choices if you choose to govern performance by the motor: Do you want a 40 mph vehicle that is punchy on the throttle or do you wnat a 30 mph vehicle that is softer on the throttle?

[GSMnow]

I tried the math and I figured 4S was the lowest I could get away with. At 3S the current goes up over 30% and the heat generated is way too much, even the 60mm motor would be hard pressed to take it. I think we all agree that higher voltage makes more power with greater efficiency. I am trying to find a sweet spot where it can make enough power to push the chassis as fast as it can go without having too much in reserve. My 4WD buggy makes about double the power than the tires can actually put to the ground. I would rather have just 20% more than it can put down. My theory is that it will be much easier to control without losing any performance because it is still capable of everything the tires can use. I hope to find out soon.

[SpEEdyBL]

Oh just edited my above post.

[kufman]

So.... do you guy think that a 60mm Medusa on 4s will be competitive in an 1/8th scale buggy? I ask because I am still trying to decide what to get. Currently I am running a Feigao 10L on 3S because that is what I had laying around. It is ok for power, but I don't think it would keep up on the track and I think the motor would overheat if I tried. I am mainly considering the Medusa 60 or 70mm, the Losi 2100, and maybe the Castle 2200 if it ever comes out. What do you guys think? :confused:

[chewie]

find a used neu 1512 2d

[kufman]

find a used neu 1512 2d

Actually I am trying to avoid the Neu's. They are rather expensive and open on the ends. Now days there are other companies that make 4-pole motors that seem to be up the challenge.

[chewie]

the neus are the most efficient motor out not to mention has the best customer service and durability why buy a ford when you can get a rolls royce for a lil more and outerwears makes mesh colored covers to keep dirt and water out but let air in

[marinearmeni]

Guys, 1509's work great in buggies, tons of power, plenty of torque and speed for the track. And I run a 50mm Medusa 2200kv in my Losi 8ight buggy, it too has plenty of power. I could use a little more snap, but it really smooths out my driving. Here's a video (http://www.youtube.com/watch?v=cYsq4M_o8PI) of my qualifier at ARC Raceway. As you can see, it's plenty fast. In the summer outside temps got past 100, but the highest I ever temped my motor was 178.
I have another video up of my truggy race where I'm running a Medusa 60mm 1300kv on 6s through a MM, that motor works great too.

[GSMnow]

There is one reason I am leaning to the 3300 instead of the 2200 motor. The internal resistance of the 2200 is the same as the 3300 which is odd, it must be a "Y" vs "D" wind difference or something like that. But that does make them produce the same heat at the same amps, so when geared for the same speed, they produce the same wheel torque when making the same heat. So going with either is a wash, and the 3300 will be usable in my 1/10 stuff on just 2S where the 2200 won't turn enough rpm for a reasonable pinion gear. A minor thing for the 1/8, the smaller pinion on the 3300 should also produce less side load on the motor shaft for a given wheel torque and road speed setup. Either motor should produce near identical results.

[SpEEdyBL]

The internal resistance of the 2200 is the same as the 3300.

That can't be true unless the rotor/stator sizes or are different. I would double check with the manufacture to make sure that isn't a typo. There are A LOT of typos/false info in online r/c advertisements that I notice all the time.

Or were you refering to the the 60 mm 2000 kv? In that case the 50mm 3300 kv would offer similar performance and heat.

[GSMnow]

I did find it very odd to see the exact same max current specs and internal resistance numbers. The higher KV should be less turns of fatter wire for lower resistance. This is why a higher KV will make more power for a given battery voltage, but the low KV will take more voltage to make more power. When I saw them listed the same, I had a very tough time saying the 3300 would be better, but the 1/10 use pushed it over the edge. Hopefully Medusa will respond to my e-mail soon.

[kufman]

the neus are the most efficient motor out not to mention has the best customer service and durability why buy a ford when you can get a rolls royce for a lil more and outerwears makes mesh colored covers to keep dirt and water out but let air in

Have you tested the efficiency? I doubt they are much better than any other 4-pole out there especially since they are just Aveox' design with a few tweaks. The Neu's were not designed for cars anyway, but airplanes just like the Medusa's. I may try one, but I would rather run something that is half the price even if it is only 98% as good.

The internal resistance of the 2200 is the same as the 3300.

This is very possible with one being a delta and other being a wye. The difference should be the square root of 3 or 1.73. If you draw out a delta and wye diagram you will see that the resistance of the wye is two coils in series and the delta is only 1 coil.

[GSMnow]

If I had the budget I would go Neu in a heartbeat. They are a very well designed package for great efficiency. They do have very low internal resistance, so it would blow away my torque limiting idea, but with the efficieny and power to spare, I could go about torque limiting in other ways and still not be lacking power. And motor heat will never be an issue. The Medusa is about 90% of the motor quality for about 60% of the price. The Medusa also has air vent holes in the ends. I have used air filter paper over my motors in the past, and will likely do that again. The Outwear filter is also a good idea. Air flow right over the actual windings is a good thing, and only the bearings will really be effected by dirt. They will take a bit of dirt through them much better than a brushed motor, thats for sure.

In a delta wind, the current is always going through one winding directly, and the other two windings connected in series, paralleled with the first. In a "Y" wind, the current is always just going through 2 windings in seies, and the third winding is doing nothing. Using the exact same windings, the KV nearly doubles and the internal resistance is quite a bit less than half if you changed from "D" to "Y". Since the KV only goes from 2200 to 3300, the delta winds of the 3300 would be more turns of thinner wire than a "Y" wind for the 2200. I opened the Neu motor page for an idea how it would stack up. They have a 1509 1.5D and 1.5Y. They come out to a KV of 4500 for the "D" and 2400 for the "Y". As for resistance, the 1.5D is 0.004 ohms and the 1.5Y is 0.007 ohms. If I try to match the 3300 KV of course they don't have the resistance on this one, but the 3600 which would still be able to be used in 1/10 ends up with a series resistance of just 0.004 ohms. That would probably push me to the 2700KV 2.5D with the 0.0082 ohm resistance.

Too bad Medusa does not list what the wind is as well, but if they are only going to list one, the KV is far more important.

[kufman]

Here is a question: Are the Medusa motors rebuildable? Can they be taken apart for cleaning and stuff?

[chewie]

I don't know but I know the neus are

[GSMnow]

Still no reply from Medusa. I want to order my motor soon, but the lack of a reply is a bit annoying. It would be nice if they just acknowledged that I wrote them. I wrote a question to Neu last year and got a reply in days, this has been almost 2 weeks. I guess I can wait a couple more days. The suspension on my 1/8 chassis still needs a lot of work. I am torn between making it run or getting a better chassis to start with. I would love to find a used 8ight or RC8to convert. I have virtually no money in this thing, and that was the basic idea, try out the power system and see if it is worth proceeding, but I am afraid this chassis may not be good enough to prove the power system. Once I freed up some binding, it now has slop, Ugh!! I was holding a nice rac roller RC8 yesterday, but at $580 I just can't do it now. I found the kit with an update pack for about $450, which is a much better deal as I like building them myself. I also found the 8ight for a bit less. I am leaning towards these two as I know every part is on the shelf within 2 miles of my house. If I like how the Medusa can throw around 8 pounds of buggy, I will be more willing to spend smome money on a chassis. So far everything I bought can be used elsewhere, so it is not going to waste. The biggest waste is the time I am putting into the chassis to make the suspension work. The drivetrain is actually good with nice steel ring and pinion sets and decent diffs. I replaced a couple bearings, but it worked out that they were standard sizes from an 8ight. I actually drove this buggy for about 3 tanks of nitro. Now I see why it handled so poorly. The front lower arms were nearly frozen from binding and one of the rear shocks had the piston broken apart so it had no dampening. No wonder I crashed it just about every time the nitor motor actually started to make power. The motor was so peaky too, it was a total handful. No torque, no torque, oh crap, spinning tires! This is the main reason I want to try it electric. Smooth electric torque anywhere I need it and working suspension should make it a lot more fun.

[porra]

Give them a call.

[GSMnow]

I recieved a reply from Jeff L. at Medusa. The maximum peak current listed should NEVER be exceeded. That is just below where the magnetic field will saturate the motor core which is very bad and will greatly heat up the motor. That is the one thing I didn't take into account because coreless motors can't be saturated, and are virtually always only limited by the resistance heating. He did not go into detials as to why, but did recomend staying under the input watts rating for long term. So at 11.1 volts (3S) you could run 63 amps, but at 14.8 volts (4S) the long term current should be 47 amps. Same watts in, but less resistive heating, so I am not sure why this would still be a thermal issue. I will write him back for more detail on this, but with my gearing I figured my long term power (anything over 20 seconds) should only be about 40 amps. Just scaling up what I get in the 1/10 buggy suggests my peak current should not go much over 60 amps before the wheels all start to spin. This is well under the saturation current spec, but will causemore than the 40 watts of resistive heating, so I will be running quite a bit of heat sink on the motor. I did order the 50mm 3300 and I should having it around Wed. as it already shipped. I will certainly try it in my 1/10 cars just to get an idea how much more power it has compared to the Mamba Max 5700 motor. On 2S I will need about a 29 tooth for the 4WD and in my truck I need a 26. I know I have the 26, I may have to find the 29 though. On 4S for the 1/8 I currently have a 93 tooth 48 pitch spur in it. I figured back that I will want about a 17 tooth for the current track layout for 40 mph, but I will start with just a 14 tooth for just over 30 mph.

I hope to have a report by next weekend

[ta_man]

I was wondering how you were going to gear that 3300 KV motor for use in a 1/8th buggy. So you mentioned a 93 tooth 48P spur gear. I doubt the 48P gear will hold up for long unless it is steel. If you go to MOD1 gears and a 52T spur (pretty big for MOD1) you would need around a 9 or 10 pinion for 40MPH. I don't think anyone makes a MOD1 ponion small enough to get you down to 30 MPH with typical buggy diffs. You many need to change your diff ratio (to "truggy" gearing) to get the speeds you want.

[porra]

Just let him do it just to see that his math will be thrown out the window fast. I say, he'll be bursting upwards into the 150-180A. He will probably see somewhere around 30-50A Avg. which will heat things up well.

[GSMnow]

I built my own spool to replace the center diff. Right now it will take diff style gears with the 3/8 inch center bore. I used 48 pitch for testing as I have every pinion in that pitch. Of course they are 1/8 shaft. So since I went witht he 50 mm motor, I got it in 1/8 shaft as well. If I go to a bigger motor later, I will go witht he 5mm shaft then. The higher rpm lower torque motor should be good witht he 1/8 shaft, but time will tell. I can easilly switch the spur to a 32 pitch which is 2/3s of the way to Mod1. I think that will hold up just fine, but I will prove out the gearing with the 93 tooth 48 pitch first. I can also easilly mount a metal spur if needed. I will have to look into sizes if needed. I will let you know when I get the motor. I will have the data logger in the car to get real current figures. I don't think I will need it, but they do have a return policy I could change to the longer can if needed.

[ta_man]

I was going to ask if you found a source for 5MM shaft 48P pinions or you got a 1/8" shaft but you beat me to it.

Don't be surprised when, you come into a corner and hit the brakes, the shaft snaps off and your car continues on at full speed. If you try the brakes on asphalt, you won't have to wait that long to snap the shaft. There is a reason Novak changed their HV motors to 5MM shafts before offering their 1/8th scale conversion kits. 1/8" shafts and 8 pound cars without slippers don't play well together. Especially with a center spool, since there isn't any opportunity for the wheels at one end of the car to slip a little on braking.

[SpEEdyBL]

Whether the shaft will break or not depends on how far out the pinion gear is. Before I switched to the 5mm shaft on my novak HV4.5 motor, the shaft would break rather quickly in my ofna mbx r2, but never broke in my 8ight with the spur rather close to the motor. Also, 48p is much easier on shafts than mod1 because the ripple forces are less severe. And even so, the 3300 medusa should have much less torque than the novak hv4.5. If it doesn't then you've got the wrong motor.

[kufman]

And even so, the 3300 medusa should have much less torque than the novak hv4.5. If it doesn't then you've got the wrong motor.

I wouldn't bet on this. The medusa is a 4-pole motor while the novak is a two pole with a large air gap.

Anyway, I finally got to test my RC8-E today on a real track, Leisure Hours in Joliet IL. I am still running a Feigao 10L with a 3S battery which ended up being just about all I needed for the 125'x65' indoor track. I wasn't quite as fast down the straight, but very close to the nitros. Jumping was a breeze. Double, tripple, no problem. Although I didn't have the ideal tire (Panther Switch 2.0) I still had descent traction with my Sports Werks premounts. The track was wet enough that there was no dust and I think I could have used slicks and been ok. The last run of the day resulted in 14.5 minutes of runtime that took 3500mAh from my 5000mAh pack. Not too bad for the cars first real outing.

[chewie]

Speaking of leisure I can't wait until the chi town shootout. Ill have to let you wheel my e rc8 with the neu 1512 1.5d/f

[GSMnow]

And you guys beat me to the full explanation. Due to the higher rpm of the 3300 motor (still lower than a 4.5 HV though) it is running a very small pinion due to the lower torque as well. My predicted currents and torques should be fine on the 1/8 shaft and I do have the gear very close to the motor bearing. Even at 2G's of braking force, the side force at the pinion only works out to about 90 oz max, just over 5.6 pounds. Doing the same math with the 2200 KV motor worked out to over 9 pounds of side force. There are times when higher rpm can work for us. Just in case, I may make up a guard that will ride close around the pinion, if the shaft does start to flex, it will rub on the guard and keep it from bending further. Since this is most likely to happen under braking, a little extra drag won't hurt much, and any scrapes in the guard will prove the shaft is not strong enough. This is an experiment in minimal setup. We will find out how well the math really works. The real data from my Mamba Max suggests it will work, we should all know by the end of the week.

[ta_man]

Indeed, an interesting test. My first 1/8th electric ran a Novak HV 6.5 motor geared 9:46. The KV of the Novak 6.5 is also 3300, though the loaded KV worked out to only around 3000. The equivalent of my 9:46 gearing using your 93T spur would have been 18:93. The actual speed was 38MPH. So you are pretty close with your eventual 17:93. If the Medusa holds rated KV under load better than the Novak, that will be real close, speed wise. The question will then be whether the 50MM motor, at about 15% longer than a Mamba Max motor, will give you the power to make a competitive buggy.

I'd be concerned that by the time you see scrapes on your pinion backup device you are already inducing cyclic fatigue stresses on the shaft.

[SpEEdyBL]

I wouldn't bet on this. The medusa is a 4-pole motor while the novak is a two pole with a large air gap.

It is absolutely a myth that 4 pole motors have more torque than 2 pole motors just because they are 4 pole. If the medusas were 2 pole and had the same specs, we would still be having the same discussion. A 3300 kv 4 pole will have the same torque as a 3300 kv 2 pole motor with the same current. Sure the novak is higher kv, but it is also capable of drawing more amps.

[GSMnow]

There are two things that limit the maximum torque of a motor. The obvious one we all know about is the DC current limit before excess heating. This has everything to do with wire gauge vs number of turns etc. This is where the 4 pole motor has an advantage. It may not seem obvious, but since the motor is effectively running 1/2 the speed due to having to do twice as many cycles per revolution, it is actually more like a 2 pole motor with double the KV geared down 2 to 1. Each coil is far less turns so it has less resistance and will take more current than a 2 pole of the same physical size for a given KV motor. And if you take the physics further, you can see that running a higher KV motor geared for the same wheel speed will give virtually the same end results for current draw and acceleration. For a given motor design, the higher the KV the less turns of fatter wire, so the internal resistance goes down so the current capacity goes up. As long as the voltage does not exceed the motor sped limits, the high KV motor could make a little more power for a given voltage.

The other current limit which is not as obvious is the saturation of the laminated steel core in the motor. This lessens the gap between the 2 pole and 4 pole motors because the poles must be half the size and therefore can not take as much magnetic flux per pole. But having 4 poles all pulling the rotor around is still an advantage. The Medusa 50 mm is a little shorter than the HV Novak motors, but the stator stack is still much longer then the opne in the normal 540 sized ROAR motors since there are no sensors in the back taking up room. The Neu 15 series motors are also larger in dia than the Medusas or the ROAR 540's at 40 mm vs 36 mm. This gives the Neu a further advantage to handle a stronger magnetic flux.

Do to the conservation of energy rules, a motor of 3300 KV will make 1345 / 3300 = 0.40757 oz in of torque for every amp supplied. The no load current draw is subtracted from this to get the true output torque. So it does not matter if the motor is 2 pole, 4 pole or a 24 pole out runner, If it is 3300 KV running at 20 amps, it will be putting out very close to 8 oz in of torque. In the case of the Medusa, the no load current is 1.35 amps, so 18.65 amps is going into making torque. So 7.6 oz in. The RPM drop from unloaded KV is determined by the electrical resistance of the entire circuit and a little of resistance from the air gap, but that seems to be a very small effect from the formulas I have seen. The biggest resistance seems to be the batteries is most modern setups now. My Reedy 5000 pack measures about 0.018 ohms vs the Mamba Max ESC at 0.0003 and the Medusa 3300 motor at 0.007 What this means is a nominal 14.8 volt battery loaded down to pull 10 amps of current will show an effeective voltage at the windings of the motor at .018 + .018 (2 packs in series) + .0003 + .007 = .0443 ohms x 10 amps = .443 volts of drop. 14.8 - .443 = 14.357 volts, so the motor rpm will be dragged down to 47,378 rpm vs the no load zero loss speed of 48,840 rpm. a loss of only 1462 rpm, or less than 3%. Now this is just at 10 amps, which is just a bit more than my 1/10 pulls when it is topped out on the long straight at Hot Rod Hobbies. The big 1/8 may suck a bit more then that, but it won't be too far off.

Coreless motors like the Mamba Max, Hackers, Feigoas etc do not suffer from core saturation since there is no metal core to saturate, and the lack of a core allow for more wire to be used in place of stator laminations, so they can usually be built to make more power for a given case size of motor. But since their inductance is so low, they tend to need more turns of wire to get the KV down close to the lamination equipped motors. Also some of the flux is wasted compareed to the lamination motors which focus more of the flux at the rotor, so in practice the ROAR Medusa Neu style motors with the laminations are more efficient at lower rpms. As rpms climb, the cores start to have eddy current losses so the coreless motors start to have an edge again at high rpm, but they are still not perfect. To get some control over the lost flux out of the motor can, they use a "back iron" between the winding pack and the can. This acts as a shield and also turns the field back into the motor, but since the field is moving with the rotation of the motor, the back iron is also going to have eddy current losses and is a major source of the motor heating at high rpm. If you ever pull the rotor out of a Mamba Max, you will feel the rotor magnet pulling into the windings. That is the back iron attracting the magnet. An aluminum can full of copper wire would not attract a magnet.

I am looking forward to putting the theory to test when the Medusa arrives. I will try to do as much head to head testing as I can with the Mamba Max 5700. The internal resistance is actually very close, so I might just have to set each one up in my 1/10 and gear them for the same 20ish mph and data log them. These are totaly different animals, so it will be fun to see. I may just toss in the Losi ROAR 13.5 just for giggles too. Then I will have a roughly 2400 KV 2 pole lamination style motor with a tiny rotor, the coreless 5700 KV 2 pole big rotor Mamba Max, and the 4 pole lamination stacked 3300 Medusa. If I run them all within limits, the math should transfer. I will have to gear it slow to compare all three. 25 to 78 on the 13.5 is about where I end up racing it, 12 to 87 on the 5700 is close and about as slow as I can fit, and 20 to 87 on the 3300 Medusa falls right in line.

[tireshredder]

Back it up a bit!
Sorry,
gsmnow is right!
Too much power can be the problem.
Not too much fun when only the ass comes around the corner.
I have a Hot Bodies Lightning Street 1:7 that is in need of brushless conversion! Mamba Monster looks like too much.
4s 5000mAh LiPo
The 4.27 Nitro shredded the tires to the rims.
My shopping list is:
CCMax/Medusa motor or
CC Monster/ CC monster motor
I fly 3D with Hacker / Phoneix power. More is always BETTER!!!

Car is not the same! Never too much power in a plane! Cars suck when you have more power and are slower on track!!!
Traction control on the way!!!

True wattage output feedback loop, Please!

Or we need a high power tourqe converter with all the loss.
Later

[tireshredder]

You should charge for the physics lesson.
We need:
Smarter ESC's and ESC users.
Power is more than we can use!
This is all good and esc firmware will get better!

[tireshredder]

Questions,
Why do current ESC's seem to drive rpm/trigger?
Can you make a power/ trigger ESC ?
sensored Vs.sensoredlesss has the same problem,
Later,

[kufman]

I think we are missing one of the advantages of a 4-pole motor and that being there there is more than one coil pulling at the same time. The other difference is that in a 4-pole motor each pole face doesn't have to pull as many degress of rotation as it does in a 2-pole. I know you guys claim that a 4 or 6-pole motor doesn't have more torque but they do, especially when compared to a novak 2-pole which has very little torque compared to other companies. The main problem with the novak is the tiny diameter of the rotor and the large air gap. I once did an experiment where I put a Feigao rotor in a novak 5800 can and let me tell you that motor was a beast! The rotor was the same length, but it was larger in diameter which cut down the air gap and the torque went way up. Unfortunately it still suffered from the normal novak wobble due to the long spaces at the top and bottom of the rotor that are not supported. The wobble could also be improved by ditching the plastic end cap on the sensor end of the motor, it can't support the bearing properly. If companies want to reduce the eddy currents in the lamination stacks they need to start using thinner laminations. The current laminations are very thick compared to what can be made.

[kufman]

I will have to gear it slow to compare all three. 25 to 78 on the 13.5 is about where I end up racing it, 12 to 87 on the 5700 is close and about as slow as I can fit, and 20 to 87 on the 3300 Medusa falls right in line.

You would gear the Medusa slower than the 13.5? That doesnt make sense. :confused:

[SpEEdyBL]

He's gearing all motors for the same speed to compare data.

Another note on number of poles vs. torque. Higher pole motors can't fit any more total wire into the can than lower pole motors. Also you can't get a given rotor to have more magnetic strength just by dividing into more poles the same way that you don't get more pizza by cutting it into more pieces. Maybe we are arguing that the design of medusas are capable of more torque than novak, but comparing two individual motors, the motor that is capable of greater speed w/o overheating with the same gearing, has to have more torque.

[kufman]

He's gearing all motors for the same speed to compare data.

Another note on number of poles vs. torque. Higher pole motors can't fit any more total wire into the can than lower pole motors. Also you can't get a given rotor to have more magnetic strength just by dividing into more poles the same way that you don't get more pizza by cutting it into more pieces. Maybe we are arguing that the design of medusas are capable of more torque than novak, but comparing two individual motors, the motor that is capable of greater speed w/o overheating with the same gearing, has to have more torque.

My main point is the number of degrees of rotation that the different motors have to pull through per phase excitation. This will have an effect on torque.

I am guessing that in his experiment he is assuming that the 13.5 has a Kv of 2400? If that is his assumption, his gearing is correct. In general, he will not see the potential of the 4-pole motor with such a light gearing. That is another thing I have noticed about 4 and 6 pole motors, they don't like to be reved out like two poles. They seem to prefer to always be under load. With my Pletty Shadow, it would get hot if I was under or over geared. I don't think I really ever found where it was overgeared, it was a beast in my TC3.

[GSMnow]

Within the tollerance of the 48 pitch gears I own, those ratios should all top out at very close to the same speed with all three motors running on 2S. The oddball is the Losi 13.5 as it is revving well past the KV x volts rpm even on the Losi sensored ESC. I certainly didn't expect that.

2 pole to 4 pole is the biggest change as the poles are 1/2 the size. The tiny Novak ROAR rotor certainly does add a variable. I was very surprized to see how big the gap is around the rotor in the Losi motor. The Mamba Max 5700 has a very small gap, roughly 0.5 mm all the way around. Without the stator stack though, the wires probably do need to be much closer. I drove my brother's Novak SS5800 with a sintered upgrade, and my 13.5 Losi seems to be about the same power. But the comparison is not totally fair as I have a 5000 LiPo on the 13.5 vs a 4200 NiMh on the Novak. Too bad he lives too far away to do a true head to head with them, using the same batteries. Not that my 13.5 works them very hard, I get 37 miunutes on the race track.

With a 36 mm can, I think 4 pole seems to be the sweet spot. Hopefully I will know very soon when my Medusa appears.

Oh, even on a 2 pole design, both ends of the rotor always have either an attractive or repulsive force acting on it. In a 4 pole, you do have twice as many, but at 1/2 the strength. I would not be surprized if the 4 poles of the rotor are actually less than 1/2 the flux of the 2 pole rotor ends. It is just physics, you can't get something for nothing. Half the mass of Neo per pole could only hold 1/2 the flux. The poles do run closer to the stator in rotation, but once again, the stator poles are half as wide as well as the pole of the rotor being half as wide. So even in 1/2 the degrees, they are actually further apart, but in that amount of rotation, the ESC has to switch to the next coil so it should be a wash. For a given KV the 4 pole will start to work better and smooth at a lower rpm, so that may be a slight advantage for a heavy car. Not really an issue with a sensored setup as they will pull stall torque til they melt.

Max torque, and max SUSTAINED torque are very different as well. Which can keep cranking out the power before it starts to overheat? I can gear the crap out of the 13.5 and it will pull hard, but it got way too hot so I had to back off the gear to match the speeds of the other Super Stock guys.

[GSMnow]

My point of ligh gearing the hotter motors is to compare the efficiency. If it goes as fast, and pulls less current doing it and runs for a longer time, then we know it is making the power by using less energy in. If I have time, I will also gear up the Mamba Max and Medusa , but I can't push the 13.5 much more without heating it too much. Maybe someone could bring a Novak 6.5 to the party?

[GSMnow]

The Medusa motor is here!

I also have the BEC and all the rest. I should have it installed in a day or two. I still need to do some suspension work on it, but the motor is already in. The shaft is even with the end of the gear, no overhang, is should be fine. The huge heat sink I picked up only needs a few fins trimmed to clear the front drive shaft. Too bad I won't be able to get any real test data for a few days. We are in the middle of getting all the rain So Cal gets in a whole year, falling in just 2 days. I am sure the track is a total mud pit by now. My yard is sinking and some streets are being closed in case of mud slides.

First test will be with a 14 tooth pinion and only 2S to wring things out. Even with 4S and the 14 inch roll out tires, it should be easy on it. 2450 wheel rpm works out to 32 mph give or take. 2S will only be 16 mph.

[SpEEdyBL]

Well I hope for the best of luck to you.

I just got my HV7.5 motor in the mail as an exchange for my HV4.5. I'll post results comparing it to my feigao 9L powerband wise. Should be interesting because the novak is slotted, the feigao is slotless, both have very different shaped rotors, but they both have about the same kv. The 9L has 2700 kv and the HV7.5 has 3000 kv unloaded, so probably more like 2500 kv under the same conditions as the 9L. The 9l should be the more powerful motor due to lower resistance, but the HV7.5 should generate a lot less heat, so I am expecting to find some kind of a balance where both motors have their advantages for a given speed. I can already say, that the HV4.5 is more capable than the 9L, but its like comparing a skyscraper to a baseball stadium. The HV4.5 can do wheelies in my 8ight, the 9L cannot. The top end power of the 9L doesn't seem to be affected by higher gearing, while the HV4.5 begins to feel weak like it is being overcome by wind resistance when geared slightly too high. I've never geared the 9L to go faster than I had normally geared the HV4.5 though. The 9L just gets too hot too quickly with a 14 tooth pinion gear (46 mph).

Anyways I am going to test both the HV7.5 and the 9L on 4s lipo. I also have a 5s pack, but I am scared to use it with my 9L, due to to overheating issues, which are most likely related to partial demagnetization of the the rotor.

[GSMnow]

SpEEdyBL, I will be very interested to hear your results. I think a lot of the Feigoa motor heat is due to eddy currents in the back iron. I don't know what they are using. If it is laninated rings, maybe they are too thick, it not enough cross section and the aluminum can is pulling eddy current. Whatever the case, is, they do make heat, even just revving up unloaded.

Well, the main reasin I signed back on was to give a very early test run opinion. I threw the front end back together, handling is not part of the package right now, one shock does not even have oil in it, but I just wanted to make it roll under it's own power. I started with the 15 to 93 gearing and just 2S. It stopped raining and the sidewalk is drying, so I gave it a few launches, sorry no data logger in it yet. On just 2S this is about 15 mph gearing. It just spins all four tires right to 15. It was pretty silly to watch. The speed is so slow it only takes the car about 4 feet of travel to hook up and be topped out. Needles to say everything was stone cold. I did notice something odd though. On just 2S light throttle makes the motor buck and jerk a bit. Not really a normal cogging, it just needs more trigger before it can turn the motor. I tried it back on the ground, and sure enough, when trying to creep it, it does take a fair amount of trigger before it will roll, but with the 6.5 pounds of mass, I could not see any of the totally unloaded bucking.

Well, I had to try it for a minute (or 6) and stick 4S in it for a quick sped run. I used my tiny 2S 3000 Max Amp packs that have both been heated to 160F and cycled well over 100 times. In my 4WD they are way down on punch from my new packs, so I was not expecting much. I was only hoping to be able to roll up on it and get it close to true top speed. Up to 7 pounds now with the 2 packs and the BEC strapped on, I gave it a quick pull, WOW!! It shot forward with all 4 tires spinning and it veered off and launched off the curb before I could get out of it. The street is still wet, but much wider, so I did a soft roll o0n and did a few flying passes. With the 15 to 93 in it still, I think it is just a tick slower up top than my XXX-4, certainly no slouch and as I got a bit brave, I was able to get it from a stand still to nearly topped out in about 10 feet on the wet asphault.

After the 6 or so minutes of launches and a few figure 8's in the street, I took it in for a look over. Outside air temp is probably just under 50F now, that will not be the norm while racing. The motor was cool to the touch still, but I do have a large heat sink on it. I could feel some warmth on the ESC, but not bad at all. The poor little Max Amp packs were probably the hottest, but even they were just warm. In use with the Mamba Max, these packs wer down to where they fell under the LVC at less than 40 amps, and I think that is still the case. If the ground dries more, I will try the data logger in it tomorrow.

So far, So good.
I have to say the motor is very well made. Certainly looks a step above the Mamba Max CM36 design. The rotor is interesting though. It is actually made up of four 90 degree slabs. I would estimate they are 3 to 4 mm thick, glued around a form on the shaft, it just might be the metal of the shaft. It is hard to tell looking in the end vent holes. I can tell though, the rotor O.D. is small, pretty close to the 2 pole in the ROAR motors.

I need to get off the computer now, it is almost 1AM here, I won't be doing any more street blasts now.

[kufman]

The rotor is interesting though. It is actually made up of four 90 degree slabs. I would estimate they are 3 to 4 mm thick, glued around a form on the shaft, it just might be the metal of the shaft. It is hard to tell looking in the end vent holes.

This is the norm for 4 pole and above motors. The rotor is usually stainless with the magnets glued on. Sometimes there will be a carbon or kevlar wrap around the magnets to prevent them from flying off. Here is a picture of my Lehner basic 4200 rotor (left, 2-pole) and my Plettenburg Shadow (right, 4-pole).

http://kufman.com/img/lehner+pletty_rotor.JPG

The Pletty is the smoothest running motor I have ever owned.

[GSMnow]

I will post back here when I actually get to race my conversion, but for the wring out testing with the Medusa motor I am starting a new thread. "Budget 1/8 brushless conversion"

[kufman]

Vids of the A and B mains from last nights electric 1/8th races at Leisure Hours.

A-Main
http://www.youtube.com/watch?v=idDD51q8SFg

B-Main
http://www.youtube.com/watch?v=84KTeSuHY20

[SpEEdyBL]

Here are my findings with the Feigao 9L vs. the Novak HV7.5. My running area was on the street outside my house, which btw, badly needs some repaving.

Vehicle: Losi 8ight
Transmission ratio: 13/43
Esc: Mamba Monster
Battery: NeuEnergy 30c 4100mAh 4s
Weight rtr: 7.5lb.
Ambient air temp: 55F

9L geared 14/49
After running this setup again, I have to take back a few previous statements I made. The 9L can do wheelies just as easy as the HV4.5 was able to, and with this gearing, it seemed just as fast as the HV4.5 ever was. I couldn’t get it to top out in the 300 feet of straight I had, while it pushed hard throughout the entire power band. However, temps on the motor were 140F after only 1 minute of running, even with the RC-Monster heat sink installed. The magnet is probably getting and more and more demagnetized every run, which would explain the rapid overheating, and higher kv than what it is rated for.

9L geared 10/49
I let the motor cool back to 100F and ran for another 2 minutes on the same pack. Like one would expect, top speed was a lot less and the motor topped out more quickly - in about 150 feet or so. But again, motor temps were 145F after 1 minute and 180F after 2 minutes. There is definitely something wrong with the motor. With similar gearing it did not heat up nearly as much when it was new, and top speed was not nearly as high.

HV7.5 geared 12/49
This is Novak’s recommended gearing, so I figured I would start with it. I used the same pack from the previous runs, but only got about 5 minutes give or take until the lvc kicked in so I couldn’t gather any fair data, but I did notice that there was more cogging than with the HV4.5. I realized I had 20% punch control set on the esc and decided to set it back to 0% (Fixed the problem somewhat, though cogging is most apparent when you try to roll the throttle). Just to make it fair I also decided to up the timing from 0 degrees to 5 degrees because Novak esc’s have some timing advancement at the sensors. Not only that, but wye wound motors can benefit from a little timing, while delta wound motors do not.

Anyways, with the pack fully charged, I got a full run in that lasted about 16 minutes. Power was significantly less than with the 9L. Very controllable, only a little wheelspin on wet pavement and no wheelspin on dry pavement. Still the motor topped out rather quickly. It only took about 100 feet of acceleration for the whine of the motor to plateau. I took temp readings twice during the run. At 6 minutes, the motor temped at 130F. At 11 minutes it reached 140F where it remained for the rest of the run.

HV7.5 geared 14/49
I actually tested this gearing before the second run with the 12 tooth, so the esc settings were the same as with the 9L. This time, the power band felt much broader. The motor took longer to accelerate and would continue to accelerate very slowly as it neared top speed, instead of completely leveling off like it did with the 12 tooth. Temps were 145F on the motor after 5 minutes and 160F after 8 minutes, and it was then when I terminated my run. The pack took 2300mah afterward so I probably would have gotten about 14 minutes of runtime had I used the whole pack.

In the end, the comparisons between the 9L and the HV7.5 were pretty much what I had expected. The power of the HV7.5 was what I was looking for. It should make a great racing motor and it’s just the right speed in front of my house where I can stay on full throttle throughout the entire 300 foot straight and not have to worry about bumps and flipping out. Since the HV7.5 with a 14 tooth was about the same speed wise as the 9L with a 10 tooth and loaded kv for the HV7.5 is probably about 2,500 (85% of Novak’s unloaded values is always a good rule of thumb for all of their motors) then this means my 9L is probably spinning at around 3,500kv instead of its rated 2,731kv. A raise in kv is typical for a partially demagnetized motor.

So here is a theoretical speed chart using 2,500 kv for the Novak and 3,500 kv for the Feigao. This is assuming no voltage drop and not tire ballooning (they cancel out somewhat anyways and I rounded down for the higher gearing and up for the lower gearing). These speeds also seemed reasonable.

9L 14/49: 59 mph
9L 10/49: 43 mph
HV7.5 14/49: 42 mph
HV7.5 12/49: 37 mph

Next I am going to test the HV7.5 on 5s so stay tuned, but I still have to schoolwork and finals to get over with, so maybe in about 2 weeks. And as soon as I can get my hands on a Castle-Neu 2650kv motor, I’ll test that as well, so then ill have two slotted motors that each have about the same kv, but much different power capabilities, and can each be safely run on 4s and 5s. OMG I’m never going to spend this much time writing post for a loooooong looooooong time. lol

[kufman]

Very interesting info Speedy.

I raced this weekend against a guy who ran a 5.5 on 4s and mechanical brakes. He was very fast and set the TQ for the night. He has to use truggy diffs in his 8ight-E to get the gearing correct. He has also killed 4 rotors, but hasnt seen any temps above 140.

My setup was a 10L on 3S power and geared at 46/16*4.3 = 12.36. I also have a large heatsink that is there as much for it weight as it is for the extra cooling. I saw no more than 125F on the motor and 150 on the controller (mm no fan) after 5 minute races. I was much slower on the straights than the 4s and 5s cars, but I was able to make up some ground on the infield. Unfortunately, my car isn't in the A-main video above because I feel to the back of the pack on the start but managed to get up to 4th by the end.

Pics of the heatsink

http://kufman.com/img/rc/RC8/RC8_Heatsink_Finished.jpg

http://kufman.com/img/rc/RC8/RC8_Heatsink_Finished2.jpg

I didn't use the fan when I was racing.

[SpEEdyBL]

Wow. That is some hardcore cooling. Thin fins definately help alot. My 9L would probably have to sit in a tank of water to stay cool during race. I've tried it on 3s and it still heats up to about 160F after only few minutes no matter what gearing.

I can see how the novak conversion concept of the motor being bolted directly to the chassis by a heatsink that wraps around the stator offers huge advantage at disappating heat. I was running the HV7.5 bare during testing and would guess it took about 8 minutes for the motor temp to reach equilibrium. My poor tekin 632 in my xxx4 with the sticker covering 2/3 of the can and a dinky mounting plate only slightly larger than the motor mounting face don't help to dispate heat. You can pretty much calculate what temperature it will be at any time during the run. If it's 40 degrees warmer than ambient temperature at 5 minutes, it will surely be close to 80 degrees warmer than ambient temperature after 10 minutes.