Biggest misconception of brushless...MUST READ BEFORE BUYING ANOTHER MOTOR

[OptimaMan]

I believe the biggest misconception in brushless motors is that "higher Kv is faster". Yes, it's faster given the same voltage, but if you have the ability to mix and match your cells to alter voltage, you can get every motor to rev to the physical limits of the motor (the rotor breaking apart due to centripetal force). So, you can get a slow motor to go the same RPM as a "fast" motor. Generally "slower" motors are more efficient also so you will build up less heat which means higher efficiency - longer battery and magnet life. Now, let's say you get a 6000 rpm/volt motor vs. 3000 rpm/volt motor. You would have to put 2x the voltage on the slow motor to get the same rpm.... but the 6000 rpm motor needs 2x the amp draw to get the same torque as the slower motor. Because you need 2x the amp, that means you need two times the capacity battery pack...and a little more due to the fact it's LESS efficient!!!


SO, for brushless, slower motors (to a point) are more powerful because they are more efficient.

Once again, here I go again... a brushless motor is only as powerful as it is able to dissipate heat. If you put 1000 watts into a motor, and it's 80% efficient, you've got a 200 watt soldering iron - if it can't dissipate the heat fast enough, you'll destroy the motor.

If you put 1000 watts into a motor that's 90% efficient, you only need to dissipate 100 watts... So, let's put 2000 watts into this motor - at 10% loss, you're losing 200 watts to heat. Of course I'm simplifying and not mentioning other parameters... but I'm doing it do illustrate a point here.

See, you want to get the MOST efficient motor possible and simply raise the voltage to get the speed you want.

So, if you want to buy your next BL motor, go slower and higher voltage.

[heavytank2]

So, instead of getting that 1920/5 you mentioned on my pan car post. I should get, oh... 1920/8? And slap on another cell or two?

[Craps]

Great post!

Now tell me if a Hacker B50 10XL motor with two 7.4 volt battery packs (14.8 volts total) is right for the Mugen 1/8th scale buggy on its way to me.

I may try two 11.1 volt packs also with this to have a total of 22.2 volts to use.

Of course you know I am talking about the TP8000 Li-Pos.

[DaFF]

OptimaMan,

Although I did understood your point about getting a slower (less Kv) motor, but lets think about this:

In order to raise your voltage for getting higher rpm out of your slower motor, you do need to get more cells (given that it's not always possible to get a higher ratio tranny)

By getting more cells (let's say 3 x 3.7 v instead of 2 x 2.7 v lipo) you will end-up with a heavier battery pack.

By getting a heavier car, you lose a lot on efficiency compare to a lighter setup.

Which can of defeat your thinking about lower kv motor are more efficient than higher kv motor (which is still true if you think motor only)

That's the reason why I am thinking that for example in your brushless HPI PRO 4 touring car you are better with :

- A Lehner 1015/12 with 6667 Kv rating running 7.4 volt lipo ( 7.4 x 6667 = 49 336 rpm theorethical)

- Than using a lower 3100 kv motor that would need to be run at least @ 11.7 volt ( 11.7 x 3100 = 43 290) and will still not be as fast as the Lehner setup

With the Lehner, you'll be lighter, will get more accel and top speed and to top it all, the lipo battery will be way cheaper ( 7.4 v versus 11.7 v pack)

Did I mentionned as well that if you try 11.7 volt on the Lehner 1015/12, you'll have an electronic rocket ?

Anyway, this is only my view on this subject, I am no brushless expert !

Please, let me know what you think.

BTW, great and interesting post you started here.

L8ter

DFF

[OptimaMan]

You guys have a point - but I do have a counter. Yes, by going higher voltage, you need more cells... but by being higher voltage, you need less capacity because amp draw is less... so instead of getting a 8000 mah 7.4 lipo pack, you can get a 6000 mah 11.1 lipo pack...

Or instead of 6000 mah 7.4 volts, get 4000 mah 11.1 volts which is the EXACT weight and size and the max output in watts is going to be the same for both packs.


It's all about power - 11.1 volt at 10 amps is 111 watts. 7.4 volts at 15 amps is 111 watts. Now, you get a slower motor that is 90% efficient, vs. a faster motor that is 80% efficient and the output of the 90% at 11.1 volt at 10 amps is 99.9 watts output while the 80% motor output with an input of 111 watt is only 88.8 watts!!!

I still contend that slower motors are more efficient - if you look at all the dyno results of the Lehner motors, you'll see that the 3100 motor is capable of almost 90% efficiency where as a 5300 is at most 80% and I'm sure the 1920 5 turn is probably closer to 75% efficient.

So, how does one go about selecting the proper motor for a vehicle for max power and efficiency?

1. How much voltage can your car hold? If you're using sub Cs, you'll obviously be limited in space in most vehicles. If you're using LiPos, you'll have a much bigger range of voltage.

2. With that max voltage you plan on using in your system, get the motor with a Kv where it will just be at redline (before rotors fly apart) with that voltage.

3. Plop that bad boy in it, get the right gearing, and get ready to REALLY FLY!

Most vehicles should be able to fit 22.2 volts (lipos) without too much trouble. My 22.2 volt 3000 mah configuration of lipos is only slightly bigger than a 6 cell pack and it can give out a continous amp draw of 24 amps which is approximately 500 watts (more than enough for my pro 4).

[Miha]

... and due to less amps there will be less trouble for the controller. You can buy cheaper less Amp controller. And also frying controller shouldn't be the issue anymore.

[DaFF]

OK, thanks guys for the clarification.

DFF

[re-inferno]

however, there's a major error in this theory!

A motor with less Kv draws less current at a given voltage than one with higher Kv

But: if you raise the voltage for the low Kv motor to gain rpm, current draw will also rise because Amp draw is proportional to tha current due to R=U/I (with a relatively constant R because we're talking of the same motor at differen input voltage)

So, that's not the point, why you should buy lower Kv motors

Instead, they generally have a better efficiency due to the windings being more dense, so a Lehner 1525-9 will have a better efficiency at a given current than a Lehner 1525-6 at any current!

Another point is the lower inductivity of a low Kv motor, that allows for easier BEC operation and better scalability (adding more celles for more speed, when needed - you can't do that with a 9000rpm/v motor if you want to go slow - it will have bad efficiency at low current)

[OptimaMan]

re-inferno - you sound like you know what you're talking about. Yes, you are most definitely correct in saying that higher voltage will result in more amperage (V=IR), however, my point was that if you got a motor that was 6000 vs 3000, and ran the 6000 so it was running at 60,000 rpm with 10 volts vs. the 3000 at 60,000 rpm with 20 volts, the 3000 rpm motor is drawing 1/2 the current of the 10 volt system with 6000 rpm motor. Actually, slightly less than 1/2 the current due to the higher efficiency (like you said, about the denser windings, less slotting, etc.)

So, I stick to my original point that a slower motor with higher voltage is a better way to go...

And Miha has a great point - less current, smaller cheaper controller! You no longer need to get controllers that need to handle 100+ amps continuous. A 25 volts controller that's capable of a "mere" 25 amps can pump out 625 watts of power!!! Plenty for most 1/10 buggies, tc, (maybe not an emaxx).

Heavytank: yeah, you got it. If you want to run up to 10 cells, the fastest most powerful motor for TC, Buggies, stadium trucks is the 1920 5 turn. If you want to more run than 10 cells, I wouldn't recommend this motor cuz you might blow it up. At 10 cells and this motor in a pan car, I wouldn't be surprised if you went close to a 90 mph. In my XXX-S graphite + with 11.1 volts (9 cells approx), geared not too tall, my TC was going well into the 70 mph (tested with GPS), but 1/10 scale TC's just aren't designed to go that fast on a semi-rough paved road. It was self-destructive.

[OptimaMan]

Daff: BTW, do you have any idea how SMALL the 1015 12 turn motor is??? It's max power is probably around 100 watts and that's being generous. It's good for the 1/18 scale, but definitely too small for 1/10 scale.

My feeling is that for 1/10 and 1/12 scale lightweight pan, TC, and buggies, a 400 size BL is the ideal platform due to size, weight, power handling. A 500 size BL is better for max power applications (speed runs, trucks, etc.)

I consider the C40 series 400 size (rotor diameter), and I consider the Basic series a "short" 500 size. The 15series motors from Lehner is a 400 size also - but you'd need to get an adapter to fit into 1/10 cars. My 1515 6 is super fast with standard 6 cells - easily gets beyond 50 mph with short gearing too.

Too many motors.... Need a way to do a dyno kind of test with them...

[heavytank2]

I totally agree, in real cars we don't have the mystery performance figure known as turns and winds, etc.

If you had an actual dyno, for the entire chassis, you could tune it VERY VERY specifically, down to gearing changes on torque/rpm, and peak torque at which RPM etc. Basically anything that a real dyno would do. This would be for the tuner.

For motor comparison it'd be nice to have a plain motor dyno. Hell, even for nitro, all kinds of motors. Because when you goto buy a brushed motor its 14x2, great. And this tells me what? There are lots of 14x2s out there, and besides the labor for a handwound, what justifies the ENOURMOUS price increase? "Its put together tighter, blah blah" Look. Machine wound, I am assuming these are computer controlled to count number of turns, and what not. Now, generally a computer is better because it virtually eliminates human error, and is generally more effiecent.

So what I am saying is, I see no justification for "hand wound" (as if there is proof, they could be just benched like batteries and the good crop is "hand wound"). And secondly, the lack of access to a dyno sucks.


The only time I've seen my motor with its specs listed was in an old RCCA mag that just listed peak torque and RPM values. Whoopie. Not specific enough, is the torque range flat? How is the powerband over an array of voltages? How does each motor react to loads similar to 4wd and 2wd drivetrains?

Thing is though, the reason none of this has been went over by a dyno is lack of need. You don't NEED an RC car to live, but companies DO need a dyno when working on the newest real-car engine of their line, etc. We are just a hobby. But hell, anything is possible, we are pretty much running out of technology for RC cars, what can you possibly do next? Turbo your 4 stroke? Where is the need in that? Brushless motors were first used in robotics/tools, I can almost bet you. They were just brought over, first in airplanes and such, and look how long it took to get to cars.

In the long run, you might see transistors improve and what not. As fetts have for many years in a row now. But even those are used in tons of industrial uses. Robotics again, probably.



BTW: After all that rambling, I recall from another post that a chassis dyno did exist for a bit, not sure if it does anymore. And dynos for the motor only do exist because RCCA used one in that mag I brought up.

[DaFF]

Originally posted by OptimaMan
Daff: BTW, do you have any idea how SMALL the 1015 12 turn motor is??? It's max power is probably around 100 watts and that's being generous. It's good for the 1/18 scale, but definitely too small for 1/10 scale

Optima,

Yes, I guess you are right for a 1015 not being powerfull enough for a 1/10 scale car.

Eventough I wonder what a 1/10 featherweight PRO 4 would require in terms of motor power...

For your info, the 1015 is a 200 W motor (info from Bishop website):

http://www.b-p-p.com/Lehner.htm

Lehner 1015 Series

Class: 200watt Speed 280/300/370/400 replacement
Size: 22 mm diameter x 31mm long. 1/8" shaft
Weight: 52 grams
Applications: An excellent choice for small lightweight airframes 20oz and less. Use when weight is critical and power demands will be in the 200watt range or less. Perfect for such planes as the Tantrum, GWS Formosa, Spitfire, P51, Zero, SlowStick, Corsair, MiniFlash, Jumping Jack, Flubber, etc. Also perfect for 1/18th scale micro trucks & cars such as the RS4 & Losi Mini-T

In a featherweight 1/10 car like yours, I wonder if a 1020 would work:

Class: 300watt Speed 300/370/400 replacement
Size: 22mm diameter x 36mm long. 1/8" shaft
Weight: 62 grams
Applications: An excellent choice for small airframes 28oz and less. Use high performance batteries for maximum power output. Use when maximum peformance is needed at the lightest possible weight in planes such as the Tantrum, GWS Formosa, Spitfire, P51, Zero, SlowStick, Corsair, MiniFlash, Jumping Jack, Flubber, etc. One of our favorite combos is the 1020/15, 5:1 GWS GB, APC 11x7, & a 3 cell nets over 47oz of thrust and 298watts!

I have no idea what the weight of a 1/18 car is, but I guess you are not too far with your PRO 4.

Using an even smaller, lighter motor would only go toward the right direction ...

I should mention as well that using a 1020, you would cut quite a bit on the price of the controller. I mean, you would be able to use a Warrior, look here

http://www.rumrunnerhobbies.com/controllers2.htm

For years everyone has tried to find a more economical possibility into the Brushless controller arena - now we have the solution! We would like to present to you our new "WARRIOR" series controllers.


Technical features:
- Two selections: 40 & 70 ampere up to 18 cells
- 3 amp BEC with off pin (BEC 100 % functionally to 12 cells)
- 15° of motor timing (in addition, it can be ordered with 30 degrees timing)
- Programmable: Forward - reverse - brake
- Water cooling & heat sink can be provided at an additional charge.
- Dimensions: 78 x 30 x 10 mm
- Weight: 20/28 gram (without cables)
- Software: 1.39/1
- Heat dissipation by high copper layers
- Partial load range optimizes


I guess 40 or even 70 Amp would be plenty for those 1020 motor.

I heard the Warrior are good esc for brushless car...

If it would work, that would do an extremly light setup, with a light price too !

Let me know what you think...

DFF

[OptimaMan]

I have a motor roughly equivalent to a 1015 motor (HiMaxx 5400 motor) . A 5400 rpm/volt one. I run that in my mini T which weighs in at a whopping 1.0 pounds. Running that at 11.1 volts and gearing very short (small pinion), I get radar tested speed of 29 mph with insane acceleration and rear tires ballooning.

It is a SMALL motor.

Also, when a company says "200" watts... or "700" watts (for their Basic series), I take it with a grain of salt. I have another motor by Razor motors - 2500a which is similar to the 1020 or 1025 motor I believe and with 140 watts of input, it gets hot in a matter of a few seconds!!! I use this setup in my 14 ounce plane.

I might try one of those little motors in my Pro 4, but I'm not sure if it's going to be truly race worthy or street bashing worthy.

[DaFF]

Thks for your reply.

If a 1020 - 280 W Lehner motor or equivalent would fit the bill, it could be roughly less 2 oz just for the motor...

3.83 oz (145 g) for a Lehner 3100 compare to 1.64 oz (62 g) for a Lehner 1020

Thinking @ the lightest setup, there might be as well some gain by swapping servo:

HITEC Mighty Mini HS5245MG @ 50$ (Tower Hobbies price)
Hi torque Digital

Torque 4.8/6.0v : 61 / 76 oz. 4.4 / 5.5 kg.
Speed 4.8/6.0v : 0.15 / 0.12 second
Size : 1.3"x 0.7"x 1.2" 32 x 17 x 31mm
Weight : 1.12 oz 32 g

instead of

FUTUBA S9550 Low Profile Digital Servo @ 80$ (Tower Hobbies price)

Torque 4.8/6.0v : 67 / 83 oz. 4.8 / 6.0 kg.
Speed 4.8/6.0v : 0.14 / 0.11 second
Size : 1.6"x 0.8"x 1.0" 41 x 20 x 25mm
Weight : 1.6 oz 45 g

Smaller, less 0.48 oz (13 g), less $30, about the same perfs ...

I am very tempted to buy a Pro 4 and trying a setup like this one, so I am looking for the best bang for my buck LoL

DFF

[extremetmaxxer]

i have a lehner 1015, and all i know is that that little sucker has waaaayyyy to much power!!!

i love it!:D

[OptimaMan]

Daff, just so you can compare, here are a sampling of some motors:

http://home.comcast.net/~youngsongdmd/motors.jpg

The left one is similar in size to a 1015 15 turn motor - note how I mounted an adapter plate already? Next is the Razor 2500 which is similar to a 1020 motor. Except, Razor is much lighter - very thin shell and holes on the mounting and end plate. Next is the Basic series, and 1920, and Novak (I just got that recently so I can compare them). A Basic XL is similar in size to the Novak and so are the Hacker B50 S series. Not pictured is a Hacker c40 size which has the same diameter rotor as the 15 series, but can is the same diameter as the 19, and 540 motors.

See how puny the HiMaxx motor is (the one on the left) as compared to a standard 540? That's why I'm thinking it might not be the greatest motor for a 1/10 scale RC.

[DaFF]

Many thanks for the picture, I wish I had as many brushless as you have !!

And yes, I see now how small is the Razor...

My mind is now set on:

Pro 4 + Schulze 18.81 esc + Lehner 5300 motor + Hitec HS5245 mini servo

(I already have Triton charger + 10 amp alim, JR Racing XR3 FM Crystal-free transmitter, Futuba R123f receiver)

For the batt, do you know when and what will be roughly the price of the 11.1 v 4000 mA 8C Thunder Power batt you mentionned on your other thread ?

For the time being, I guess I could use two TP21003S @ 6C, but if the 11.1 v 4000 mA show-up soon, I'll rather wait for that lighter setup

Still have to find out the best rim/tires and body and then I am all set for a wild 1/10 sedan !

L8ter

DFF

[OptimaMan]

5300 is a great motor - but are you sure you want to go that fast? Even with a FDR of 9:1, you'll be approaching 50 mph!!!

The newer thunder powers will come out in the next several weeks (according to my LHS), the best thing is the lower internal resistance - not the weight. However, Kokam already has the 8C cells out - you can get a 2000 mah 11.1 volt pack at Tower for $82.95

If you had a slower motor (such as a basic 3100), you could get by with just one pack with easy gearing, but with a 5300, I'm recommending at minimum 4000 mah at 8C and with this setup, make sure the batteries don't get hot!!! I don't understand why you would want to get such an inefficient motor as the 5300 though. I would rather you go with a 3100 and get a 11.1 volt 2000 mah pack and 7.4 2000 pack hook them up in series. You'll have roughly the same speed, better efficiency, and less heat buildup (the whole point of this thread).

[heavytank2]

Blah I musta been tired. Didn't read it right... edit.

[DaFF]

OptimaMan,

I have to think at what you said...

I mean your 3100 setup will cost me roughly:

225$ for the Schulze 18.71K esc
148$ for the Lehner 3100 motor
56.5$ for the 2000 mA 7.4 v pack
82.95$ for the 2000 mA 11.1 v pack
---------
512.45$

Considering the fact I would buy at least 2 pack in order to swap them, that would set me up for 512.45 + 56.5 + 82.95 = 651.9$


The schulze esc is kind of expensive, and the use of 11.1 + 7.4 pack is to my opinion not the best.

I would prefer to use the cheaper 7.4 volt pack times two, so that I can purchase 4 identical 7.4 pack that I could use as I wish i.e. 2,3 or 4 pack depending on the run time I need.

Furthermore, if I can get a Warrior 40 (40 Amp, 114$) or a Warrior 70 (70 Amp, 135$) there would be a good price cut.

114$ for the Warrior 40 esc
148$ for the Lehner 4200 motor
2x56.5$ for the 2000 mA 7.4 v pack
---------
375$

Let's say I buy 4 pack for swapping, total is 375+113=488$

See what I mean ?

My opinion is that a 18.71 esc with 61 Amp cont. and 81 Amp peak is kind of overkill in a less than 2.5lb sedan setup.

Would you have any idea of how much Amp roughly can be drawn by your Pro 4 with:

A Lehner 5300 running under 11.1 volt (58 830 rpm)
A Lehner 4200 running under 14.8 volt (62 160 rpm)
A Lehner 3100 running under 18.5 volt (57 350 rpm)

Digging it a bit, it seems to me now the 4200 setup would be the best balance for price / perf / efficiency and overall weight, not to mention most practical with the use of the same ( cheap and light ! )7.4 volt pack...

Thanks again for your help !

DFF

[OptimaMan]

I would NOT get a warrior 40. I used to have a 1895 (which is a higher end version of the warriors) and even with updated software, it would cog. With an external pack, it wouldn't cog anymore, but it wasn't all that smooth. Not like a Schulze smooth at least. You would be much happier with the Schulze in terms of performance. In a couple of months, castle creations will have a Mamba 80 coming out. That should be pretty good...

Next, a Basic motor is only 120 through bishop power products (including S&H).

If you want to go with a 4200, I would say it's fine - you have to be careful however, not to put too tall a pinion gear and always monitor battery temperature.

With the 4200, all you would need is 11.1 volts. With that voltage and rpm, with a FDR of around 9:1, you'll still top out close to mid to high 30's. With an 8:1, you'll be in the low 40 mph range. This motor could easily handle smaller FDR - such as 6 or 7:1 which would result in speeds in excess of 50 mph - but you might have to parallel 3 packs to keep the amp draw within range of the batteries. Playing with the gearing and battery combo is the key here. To answer your question about amp draw... that's difficult. It totally will depend on gearing. If you gear the 5300 20:1 fdr, you'll pull less than 10 amps. If you gear the 3100 3:1, you'll pull 100 amps. This is trial and error and the only way to tell is to measure the battery temperature to keep it within the safe operational temps (so you don't degrade them) and by keeping tabs on overal run time, you can calculate average amp draw.

OH, I just got it - just attach an Astro-Flight super Whatt meter to it, and drive around for like 5 minutes with that setting. When 5 minutes is up, read how many mah is used up according to the super whatt meter. Do a little math and you can figure it out pretty easily then... what's a super whatt meter? Look at Tower's page, they have it - but it's not cheap - it's like 60 bucks.

[havy]

OK I have to ask... been thinking about these set-ups...

At my local races, they aren't too BL friendly, the class is 10t mod motors, 6 cells. If I show up w/ Lipos I definitely won't be able to run. So lets say I run a 6 cell GP3300's. I guess efficiency isn't that much of an issue since races are five min. In this case I would want a big Kv motor Lets say Lehner 1520/8 (or /5 ? something w/ greater than 6000kv in order to have a BL advantage right?) w/ a controller that could tolerate 80amp peaks would be good?

This is alot diff from what I posted about the TC3 200mm car(that's a fun progect), this would be for me to run Touring car at the local level races.

Havy

[OptimaMan]

If you have to have 6 gp3300 cells, you should consider these:

Basic 5300 - Something like a 10 turn
Hacker c40 6s - something like a 8 or 9 turn
Lehner 1920 5 turn - unlike any brushed motor I've ever ran or seen. Even with tall gearing like 5:1, all 4 wheels will spin out to 60 mph!!!

Make sure you have a controller with a heatsink and don't gear too tall. The hacker c 40 6 s used to send my XXX-S G+ with a Schulze 12.97 fwe into overload all the time on a carpet track with foam tires geared at 10:1. A 12.97 with heatsink would fit the bill. Mine didn't have a heatsink.

If you want to seriously beat all brushed motors, roast them alive, kill them, smash them, etc. the latter two motors with a 18.129 fwk would kill em all... but that's rather expensive.

A cheap cheap alternative is to simply go with novak ss5800. It's decent performance, and unless you are an expert driver, probably more than enough speed for an indoor track. Just don't gear it too tall or else you'll roast the controller.

[havy]

Great Opti thank you,

I don't like the novaks, the sensored motor wouldn't alow me to use the other option in the prior TC3 project post I wrote about earlier. I want something I could use for both, just exchange batts and I'm able to do both. 1950 Lehner seems to be the ticket. There are two big tacks here and the others are smaller parking lot tracks so I would definitely be looking to smoke them;). I don't mind spending a little more for the initial investment as in the long run I think it's better to play it safe.

Thanks again for sharing your experiences. I appreciate you sharing your info w/ us.

Havy

[NIC]

havy:

You seem to be very "powerhungry" :). I think you should get the 18.129 or even the newer 18.149 with dual cables wich is out very soon. Check the Schulze site for info on it.

If you get the 1920/5 and some topnotch GP-cells you will be pulling ALOT of amps in you car. You will have one of the most powerful set-ups you can get with 6 cells and it just make sence that you should have the most powerful esc to be on the "rather" safe side.
Take into consideration that the best GP:s can give up to 200 amps for a short time and that is alot more then the 128 amp-bursts the 97-amp controllers can handle.

I have the 18.129 and it´s working great in all my cars. I can highly recommend it.
And the fact that it works great for both extreme set-ups on 6 cells and all the way up to 18 cells makes it a really allround esc.

And the hole meaning of this thread. GREAT thing you started it OptimaMan !!

If you don´t go for the LVHC (low voltage, high current) approach and use a higher voltage and lower current set-up (let´s make that HVLC) your controller will NEVER break a sweat and therefore be VERY efficient. The FET:s loses there efficiency as the tempeture go up.
Your controller will therefore also have a huge safety margin for breakage.
You don´t drive around on first gear on your real car, then why should you have your esc at redline all the time ?

One thing about the 18.129 is that it doesn´t have a BEC. First I didn´t like the idea of having a receiver-pack or other powersourse for the servo. But I have changed my mind about that. Since the BEC is only 5V on the Schulzes, they make my servos slow and that mess up my driving more then having, in this case, a 35 gram receiverpack.


GREAT thread OptimaMan ! Keep up the good work !

It´s threads like this that´s good for all the people throwing big bucks into BL or considering to buy BL-equipment for their hard earned money.


NIC

[rcconcept]

What about a Hulkin truck like a Clod buster?What motor & controler would work?

[rcconcept]

Note:A clod would need two controlers & two motors.This because one motor has to turn in reverse rotation.Also I will be running 7.2/4 & maybe 11.1 volt batteries

[OptimaMan]

Two controllers and two motors. You would just have to run one of the BL in reverse.

I don't know the FDR of the clodbuster so I couldn't give you an answer. In addition, what are you looking for? High speeds? Good crawling? Good 30 mph bashing around construction sites?

[alpinesky1]

OptimaMan - ok, say i had a RC10T4, and it had a Hacker Master Car Competition Controller, and a C40 6T Motor, and a 2cell/7.4v 6000mah. Lipo battery pack............

Lets say the truck is getting 25mins. of runtime doing 35mph topspeed -
C40 6T/ 7.4v 6000mah/ 35mph/ =25mins. of runtime

Now say i got a 3cell/11.1v 6000mah. Lipo battery pack, from what you are saying before a (3cell/11.1v 4000mah. would have the same runtime with the right Higher turn C40 motor geared to 35mph, as a 2cell/7.4v 6000mah Lipo battery pack) right?

C40 ?T/ 11.1v 4000mah/ 35mph/ =25mins. of runtime
C40 6T/ 7.4v 6000mah/ 35mph/ =25mins. of runtime

So then would the following be true
C40 ?T/ 11.1v 6000mah/ 35mph/ = 37.5mins. of runtime
Witch would be equal to -
C40 6T/ 7.4v (8000mah)/ 35mph/ = 37.5mins of runtime

Am i getting this right?

[rcconcept]

I don't know the FDR of the clodbuster so I couldn't give you an answer. In addition, what are you looking for? High speeds? Good crawling? Good 30 mph bashing around construction sites? I believe the clods F.D.R is 30.08:1.Basically I what the bl`s for bashing & 30 mph sounds good.

[OptimaMan]

alpinesky:

You're starting to figure it out... except, here's what's probably more like it:

C40 ?T/ 11.1v 4000mah/ 35mph/ =30-35 mins. of runtime
C40 6T/ 7.4v 6000mah/ 35mph/ =25 mins. of runtime

I'm totally speculating here - but a C 40 6 turn is probably no more than 75-80% efficient from 10-50 amps while a C 40 9 turn is probably something like 85-90% efficient from 10-40 amps.

AND, since you're pulling less amps, the controller will stay cooler and you'll have less power loss due to controller and wiring. The controller itself will probably be 5% more efficient running cool vs. hot.

Now, a C40 9 turn with 11.1 volts will give approx 50000 RPM while a C40 6 turn with 7.4 volts will also give approx 50000 RPM. So, you would put the same gearing on them. Have the same top speed and acceleration.

Now, a 9 turn on a 11.1 volt 6000 mah will run even longer than a 6 turn on 7.4 volt 8000 mah because more total energy in the cell (1 additional lithium cell) and the extra efficiency of a higher turn motor.

A 7.4 volt 8000 mah is 2s4p (2 series, 4 parallel for a total of 8 cells) A 11.1 volts 6000 mah is 3s3p (3series, 3 parallel for a total of 9 cells).

[OptimaMan]

For a clod to go 30 mph, you would need two controllers and two motors. You would also need to run the 12 cells in series so each controller and motor combo will get the full 14.4 volts.

With a FDR of 30:1, with 2 basic 4200's, you'll be looking at speeds of around 35 mph.

If you decide to go with Basic 3600's, you'll be looking at about 30 mph.

With Basic 3100's you'll be looking at high 20's.

My recommendation is to go with the Lehner Basic motors due to their high torque, small packaging, and great power. With controllers, you can get two 18.61K's - but that's 450 bucks alone!!! You can wait for the Mamba 80s which should be less than that and coming out in the next few months. The two basic motors will run about 250 bucks total. Wow, that's quite an initial investment!!! 700 bucks!!!

Why don't you just get a stripped down emaxx for less than 200 bucks? Buy one less motor and controller, and you're still at a lower cost than getting a clod setup!

[alpinesky1]

Originally posted by OptimaMan
alpinesky:

You're starting to figure it out... except, here's what's probably more like it:

C40 ?T/ 11.1v 4000mah/ 35mph/ =30-35 mins. of runtime
C40 6T/ 7.4v 6000mah/ 35mph/ =25 mins. of runtime

I'm totally speculating here - but a C 40 6 turn is probably no more than 75-80% efficient from 10-50 amps while a C 40 9 turn is probably something like 85-90% efficient from 10-40 amps.

AND, since you're pulling less amps, the controller will stay cooler and you'll have less power loss due to controller and wiring. The controller itself will probably be 5% more efficient running cool vs. hot.

Now, a C40 9 turn with 11.1 volts will give approx 50000 RPM while a C40 6 turn with 7.4 volts will also give approx 50000 RPM. So, you would put the same gearing on them. Have the same top speed and acceleration.

Now, a 9 turn on a 11.1 volt 6000 mah will run even longer than a 6 turn on 7.4 volt 8000 mah because more total energy in the cell (1 additional lithium cell) and the extra efficiency of a higher turn motor.

A 7.4 volt 8000 mah is 2s4p (2 series, 4 parallel for a total of 8 cells) A 11.1 volts 6000 mah is 3s3p (3series, 3 parallel for a total of 9 cells).

Ok, i see now with more Volts, youll get the same power at a lower amp!;) :cool:

Hmmmm... now i got to call thunder power and see if i can fit a 6000mah 3s3p in my T3/with a little moddifying..

Thanks

[OptimaMan]

Exactly! See, Power = Amps x Volts
So, watts = amps x volts since watts is power
So, a 100 watt lightbulb at 100 volts is only using up 1 amp.
Got that?

[heavytank2]

Exactly like torque vs. RPM = HP.

You can raise or lower either one, but you can make both of them still equal one HP.


But in this case, less amps = you can use a lower controller, less heat, etc.

[Craps]

Optimaman
The Li-Pos in the 1/8th scale work with a huge success, but I know I am going to battle the heat factor.

My question is will more voltage get lower running tempertures due to being more effiencient?

I have been using the pair of TP8000-2S4P 7.4 volt batteries that give me a total of 14.8 volts and I hope to have a pair of TP8000-3S4P 11.1 volt batteries with a total 22.2 volts to power the Hacker B50 10XL motor with a Schulze 18.97KWF ESC.

Heat now is a bigger enemy inside a closed body on the buggy versus the motor being in the open on the truck.

Also the more voltage, more RPM, more effiencient should make it where I don't have to drop pinion size to cool it off what I am running now?

Keep posting this great information to help the Novice racers like myself!

[OptimaMan]

Craps: I don't consider myself anything more than a novice myself when it comes to brushless and lipos also...

But, with regards to running your 1/8 scale with less heat build up etc, you will most likely benefit from higher voltages and lower amp draws.

Now, you are already to the point with your motor where you really can't get more efficient - so you don't need a slower motor.

If you plan on going 22.2 volt, you probably will need to drop pinion size a bit because using the same motor and pinion and just going UP in voltage will actually increase amperage quite a bit too, however, going up in voltage and dropping the pinion to match the speed will significantly reduce the amperage.

For starters, if you're going to 22.2 volt, why don't you get the pinion you are using now, and multiply it by .67 You should get just a tad faster (less loading on the motor) and even more torque. Then gear accordingly.

Remember, going up in voltage using the same motor w/o appropriate gearing change will actually increase amp draw and build up MORE heat.

Craps, is it the motor that's getting hot or the batteries?

[Craps]

The motor and the ESC. The Schulze 18.97KWF takes the heat better than the Hacker Master Comp did and the batteries are warm because the heat is held inside the buggy body which I helped it some by cutting vent holes where the windows are.

I am also going to add 2 fans, 1 for the motor and 1 for the ESC. The batteries are performing like I expected them too. Great!!!!

I like the bottom end acceleration and mid range power with the 14.8 volts and the gearing I am using now, but I think the 22.2 volts will give me top end that nothing on the track will come close to touching on the long straightaway tracks that are built for 1/8th scales.

B50 10XL
1,578 rpm per volt @ 14.8 volts= 28,354 rpm
1,578 rpm per volt @ 22.2 volts= 35,031 rpm

Huge gain in power!

[alpinesky1]

OptimaMan - DAM DAM DAM!
Thunder power emailed me an a 6000mah 3s4p/11.1v will not fit in my T3:mad: :mad: :mad: ...........

So i have to stick to a 2s4p/7.4v :o ........

I was really looking forward to 11.1v ...oh well

now i guess im back to 7.4v on a C40 8T , im going to get tp8000mah packs unless they come out with something bigger:D .

My truck should still be fast:p , i just wish i had 11.1v with 30mins of runtime:)

[Craps]

Originally posted by alpinesky1
Thunder power emailed me an a 6000mah 3s4p/11.1v will not fit in my T3:mad: :mad: :mad: ...........

So i have to stick to a 2s4p/7.4v :o ........

I was really looking forward to 11.1v ...oh well

now i guess im back to 7.4v on a C40 8T , im going to get tp8000mah packs unless they come out with something bigger:D .

My truck should still be fast:p , i just wish i had 11.1v with 30mins of runtime:)

Why will it not fit?

Is the battery too tall, but the same width and length as the TP8000 and 6000 2S4Ps?

A dremel tool and velcro straps can solve alot of problems.

[alpinesky1]

Craps - i was wanting to put a 3s3p 6000mah. Lipo in my T3, but it is a good 1/3" plus sum too long to fit,(the width, and tallness is fine) theres just no way to fit it..
So im going to get the 2s4p 8000mah battery, its the biggest that will fit:rolleyes: well on the good side ill still have 30mins+ runtime:) ..... im just pickky pickky:p


When you get your 3cell lipos for your 1/8th buggy try fitting them in your T4;)

[Craps]

Yes, but they are TP8000-3S4Ps.

[OptimaMan]

Alpinesky, just send that 11.1 volt battery to me!!! I'll use it!!!

[DaFF]

Back from the dead ! ( for you Andrewg )

DFF

[studysession]

i have a lehner 1015, and all i know is that that little sucker has waaaayyyy to much power!!!

i love it!:D

What do you have this motor installed in? And do you have pics that you are willing to post?

[studysession]

OK - Need some help. I have been looking at the Lehner motors myself and want to get another one.

Where do i find the size of the can in milimeters?

I currently have a 5300 basic, but want some other motors for different applications and size of the can determines which motor to get.

Many Thx

[DaFF]

What do you have this motor installed in? And do you have pics that you are willing to post?

Study, I don't think you'll get an answer anytime soon... if you look at when this post was done, you will discover it was 6 month ago, in March 2004 !

DFF

[studysession]

Yeah, I saw that. But figure if he does see it and still have pics. It would be nice to see.

[rca]

If you have to have 6 gp3300 cells, you should consider these:

Basic 5300 - Something like a 10 turn
Hacker c40 6s - something like a 8 or 9 turn
Lehner 1920 5 turn - unlike any brushed motor I've ever ran or seen. Even with tall gearing like 5:1, all 4 wheels will spin out to 60 mph!!!

Make sure you have a controller with a heatsink and don't gear too tall. The hacker c 40 6 s used to send my XXX-S G+ with a Schulze 12.97 fwe into overload all the time on a carpet track with foam tires geared at 10:1. A 12.97 with heatsink would fit the bill. Mine didn't have a heatsink.

If you want to seriously beat all brushed motors, roast them alive, kill them, smash them, etc. the latter two motors with a 18.129 fwk would kill em all... but that's rather expensive.



Can anyone shed some light on this,will the U-force 75 be able to handle the 1920 5 turn running on sub C 6 cells? What size is 1920 series? Are they the same size as brushed 540 and a direct fit to standard 1/10 cars?Where can I get 1920 5 turn? BK electronics only have up to 10 turn.Any comments would be much appreciated.Thanks.

What about Hacker Master car comp esc which can handle 90 cont. amp and max 120 amp?Any information on the performance and durability of this bl esc?