Advice for Brushless setup on TC3

[FninjaP90]

So to start, I'm going to get a FT TC3 with titanium driveshaft and power a Lehner Basic 4200 with either 14.8V 3000mah Li-poly pack or a 14.8V 4500mah pack.

Now which ESC should I pick? I don't need an expensive, super hardcore fully programmable and customizeable one, just one that would work. Now at 700W, the motor will be drawing 47.3A. I have my eyes set on the Castle Creations PHOENIX 60 (http://www.aircraft-world.com/shopexd.asp?id=301), the Hacker MASTER 70 OPTO (http://www.aircraft-world.com/shopexd.asp?id=2126), and the Jeti ADVANCE 70 OPTO (http://www.aircraft-world.com/shopexd.asp?id=332).

What are the pros/cons of each one? The Jeti and the Hacker appear the same, but why is the Hacker $10 more? Are there any other ones I can consider?

[ElectricThunder]

I'm not sure that those 3 ESCs will actually work in RC car applications. I think the CC is for airplanes, the hacker for boats, and the jeti for airplanes as well. Starluckrc or someone else will have more knowledge on those controllers probably. A cheap ESC to consider is the BK/Lehner Warrior 7018. Lipo capable, 70 amps continuous, 18 cells, and costs about 170 bucks off of www.bk-electronics.com

www.starluckrc.com will have BK stuff in a month or two probably, as well as some schulze stuff, etc. ;)

[starluckrc]

You will be highly disappointed in brushless if you use one of those controllers. You need a controller with software specifically for car applications. The Warrior is the cheapest I know of that will work.

[FninjaP90]

Thanks for the info!

Starluck, when you get the Lehner motors and Tanic li-po's on your site, how much will you charge for Lehner Basics and Tanic 7.4V 2S2P 1500mah packs?

[havy]

Hi,

CC will be out w/ a new 80amp contig. controller for 1/10th soon. I finnally have in my hands a IRS conversion TC3 which I will be running w/ 5407t I got from Starluck (great to do business w/). Just waiting on the CC controller to come out. Beta'd the Mamba and currently still run the beta on my M18 BL micro and love it. Should better that the Mamba for sure and that is not an easy standard to beat ;) .

I hope to be able to get some GP 4/5 2200 sub-c cells for a couple of 8 packs to push the car and motor through their pases.

I would like to hear about your experiments w/ gearing when you do get to running it.

Good luck,
havy

[FninjaP90]

Considering all the power the setup will have, probably the biggest pinion and smallest spur I can find, probably 35:69, bringing a final ratio of 5:1, enough to propel the car to theoretically 88mph when the motor is turning 70000rpm, so I'll probably top out at 80mph or so.

[havy]

Talking about pinions and spurs. What kind of rollout should I go for using the 540 7t (pinion/spur combo)? I will be racing on 6 cells running in a class that has no motor turn limit for the normal brushed motors.

I will also be trying 8 cell pack w/ this same motor for fun purposes ( hopefully 4/5 GP 2200 when available).


Thanks,
havy

[FninjaP90]

Hmm probably a mid to mid-high setup, depending on your track.

At 14.8V, the 4200 will only be pulling 62160rpm (77.7mph), nothing near the brushless limit. But at the same voltage, the 5300 will be doing 78440rpm(98.1mph). Will this rpm blow up the motor? What motor should I use given the voltage supply?

[havy]

I think yo have to go w/ a 19 series or 15 series lehner to be safe at that high a RPM. Not sure though, you might want to verify this.

1520 6t might be a good choice.

havy

[DaFF]

FninjaP90,

I already have a setup similar to the one you plan to get i.e. Lehner Basic 4200, Shulze UF-75 and 14.8 volt lipo.

My first advice would be for you to get a good esc, not saying the Warrior is not bad, only saying the U-Force is superior.

Second, be extremly carefull with your Basic 4200 under 4S ( 14.8 volt ) lipoly.

- The Basic is rated at 65 000 rpm max
- Although you think the lipo will send 14.8 volt, it is way more when fully charged i.e. 16.8 volt leading to way more than 65 000 rpm ( 16.8 x 4200 = 70650 rpm...)
- The Basic can get pretty hot when playing with the max rpm limit, I suggested the UF because with the PC link you can set-up the rpm limit to 65000 to be on the safe side ( highly recommended )

Third, although it might be possible to hit 80 mph, I'll recommend to you to try LOW gearing at first, otherwise you might end-up blowing your expensive Lipo cells. Hint : Be carefull when selecting your 4S ( 14.8 volt ) Lipo, the 4200 under TALL gearing could suck around 50 Amp, might even be more in short spike Amp draw.

Use only the very last gen high discharge cells to be on the safe side.

One think that I can tell you : be prepared to have your hand full with this setup, it can be extremly fast ( actually: ridiculous fast :rolleyes: ) and difficult to control !

Anyway, what Lipo are you thinking at ? ( Brand, mA ? ) and in what car ?

DFF

[reznikvova]

Anyone have any experience with the Warrior 1895 BECMicrocar?
Picked one of these up for 200 shipped.

[FninjaP90]

I plan to make my own packs from these cells: http://www.unipros.com/cbpsite/packs.asp?cat=LIPO&session_id=180466

I asked Mike at CBP and he said that they are the same cells used by Poly Quest.

Even though a pure 16.8V power supply will crank the basic over its 65krpm limit, , the tremendous amp draw will make the battery voltage drop, enough to a point where a freshly charged pack won't even make 14.8V to the motor.

700W/14.8V=47.3A, which is a bit more than a 15C burst capable 3000mah Li-po pack can handle, so maybe I should go with a 4S3P 4500mah pack? 47.3A from a 4500mah pack is only 10.5C.

[TheSteve]

Keep in mind the motor has a 700 watt rating as the maximum power it can handle, there is nothing to stop it from taking double that power (or more) if you provide it with enough voltage and load. So don't assume the most current it will ever take is 47.3 amps.

[starluckrc]

I agree with TheSteve. I've seen spikes that double the rating of the motor I was using.

[FninjaP90]

So what should I do about that? Get the 1300W motor? Is there anyway for the ESC to limit the power going to the motor?

[Andrewg]

Fninja

If you want to run such high voltage try a lower rpm/v version of the Basic - you will get a wider powerband and better efficeincy.

At 9 v the 4200's maximum efficiency point is 50 amps at 14.4 it will be near 70 amps. This means either you set top speed for 70amps max eff. in which case you will pull more than 70 amps most of the time - and your controller will be very likely to pop its rocks or you can do the more common thing and set the gearing low to reduce the current draw. In this case you will drop into a range where this motor isnt that efficient which defeats at least half the purpose of brushless.

A lot of guys do this and are amazed at how good the motors are - but they are missing out on a lot of runtime and performance flexibility.

A better motor on 14+ v would be the Basic 2700 which will have max efficiency at around 30-36 amps a wider power band and more torque. It will also be much kinder to your controller. Runtime will be significantly extended and the setup will run much cooler.

Regarding the controllers

The Hacker you mentioned earlier is designed for sticks not a wheel. The Jeti controller isnt really what you want - its ok but lacks adjustability.

Hacker have an excellent car controller which is easy to set up. It has adjustable timing from 2-30 degrees; Adjustable Current Limit or No Current Limit; Fully proportional Brake System; Programable Reverse "On or Off"; and good power handling. And computer link

Schulze is likewise excellent: Their products are very high quality with great service with computer setup. It can also be used on brushed motors.

The Castle Mamba 80 is not out yet as far as I know but the Barracuda which uses the same software in a marine setup is recieving good reports. there backup is second to none and closest to home.

[FninjaP90]

But at 14.8V, a 2700 would only be spinning at 40k rpm, nothing near its limit. I thought high turn motors needed more voltage to spin it, right? Or is 40k rpm the sweet spot for brushless motors?

About the controller, do they limit the power going to the motor? Because if the motors actually do spike, that means I'll fry the motor, controller, and pull too many amps and fry the lipos. Therefore setting the entire car up in lithium flame.

[Andrewg]

""But at 14.8V, a 2700 would only be spinning at 40k rpm, or is 40k a sweet spot for brushless.

The sweet spot for any electric motor is where it converts the highest percentage of available electrical energy into rotation. For any motor runnign at constant voltage this is expressed in terms of the percent of energy converted and the amp draw at which it occurs e.g. 92% at 45 amps

As a rule more voltage raises the efficiency of a motor and it raises the amps at which it occurs. Too high a voltage and the motor will overheat drawing the amps it needs to run at maximum efficiency. BTW Lehners site has dyno charts for the Basic 4200 but only up to 9v - does that say anything to you?

Motors like the Basic XL 2400 are tested at 13v and its clear why better efficiency and much better torque. My suggestion of the 2700 basic was just an effort to save you $20 but really the XL would be a far better motor.

In effect using a 4200 is like putting a drag motor in a touring car - real or electric - (the Basic 4200 has similar electrical characteristics to a 7/2 G-Force drag motor which would usually run on 7v - on 14v you might run a 10-12 turn and no esc would be expected to live through it) - lots of heat and very short life

You are worried about not running at the limit. WHY????? What does limit imply? One thing is bearing failure -> locked rotor -> fried electronics; another magnets leaving the rotor -> scratch one motor. Motors used at their limit also have a monotonous habit of blowing controllers simply because the can pull huge current at stall - or form a standstill or if the drive train was to jam - try 180 amps for the 4200. With brushless limits are there for a reason.

Someone is going to say gear shorter and reduce your amp draw. You do that and run with lousy efficiency - you will have an overheating motor or less performance or less runtime.

By running a motor like the 2700 or the XL2400 you drop the amp draw at max efficiency to about 45 amps but because you run high voltage your efficiency is about 87% - 92% withthe XL. With this setup if you want to go faster just put in a taller gear and draw more current and you can do it safely. And you get great runtime.

IMPORTANTLY even the 2600 will be making about 80 watts of waste heat at max efficiency. Think about how hot a 40w soldering iron gets and double it - this motor is working hard. A 4200 running at peak efficiencywill be making in excess of 120watts - damn hot if you try to use the motors potential.

This is effect is especially important with LiPo cells - you can get away with high waste heat for a 1.7 second run like that drag motor i mentioned, or from a 2 minute run - but when you got to 10 minutes of runtime the motor will accumualte a lot of heat.

Btw all electric motors "spike". They pull max current and make maximum torque at 0 rpm - this is called stall current. At approx 50% of peak rpm they make maximum power usually at about 60% of stall current but it is converting energy so inefficiently that is would risk overheating pretty rapidly. At max efficiency where the motor runs coolest a brushless is still making about 90% of the peak power. At peak rpm the power output is usually negligible and the amp draw all that is required to turn the motor when it has no load

So go for the 4200 - but to keep it together it will be inefficient or go for a lower rpm motor and operate without having to worry about your electronics and enjoy high speed and good runtime

An electric motor has a sweet spot and it is to do with volts and amps - the rpm are largely incidental.

Go here to see charts of the Lehner motors http://www.lehner-motoren.de/motordia.php to egta better idea of what works well.

And the Hacker controller limits current - but use it only if you want to waste potential power

[Tc3basher]

sorry guys, posted in wrong thread.

[FninjaP90]

Wow, thanks for the info Andrewg. You just about tripled my brushless knowledge.

So it looks like I'm set on the XL 2400.

Do you know when the CC Mamba 80 will come out? Is the Warrior 7018 really that much inferior compared to Schulze and Hacker Car controllers?

[DaFF]

FninjaP90

IMHO a XL in a TC car is something unheard before, only ppl interesested in top speed ( like Cliff Lett with his 111 mph TC3 ) would use such a setup.

I can only tell you that your car might perform good on a straight line, but for me, it will be far from the best handling car.

If you want to use the XL, be ready to add counter weight on your batt side or at least use a 7 or 8 cells setup.

The TC3 and the Pro4 share the same weight repartition, i.e. electronic & motor on one side and batt on the other. It means that every time you add weight on the motor side, you have to add also weight on the other side.

It doesn't seems much but a Lehner Basic weight 145 grams while a XL is 205 ( that's 60 grams difference, which is rougly the weight of an extra Nimh cell ).

Furthermore, because you'll be running a TALL gearing, the motor will be pushed outward, which will be an aggravating factor.

Also, I can almost guarantee you'll experience a LOT of motor torque steer, because the rotor of the XL is twice the weight of the one from the standard basic. This is something that I discovered with my BL setup and it is very difficult to find counter measure to combat it.

Lastly, be also carefull with the lenght of the XL, it is almost twice as long as a standard Basic which could lead to space problem on your TC3.

I can't stress enough how the weight repartition is critical on a TC. I highly recommend to use a digital scale or at least to have a mean to check your right / left balance.

Anyway, please report back if you decide to do this setup.

I wish you good luck.

Andrewg,

I hope you understand that I am in no way starting a flame war, I'm always interested in exploring new setup and comparing it to existing one.

I can tell you I am only a babyborn on the BL r/c car world.

I shall be able to report on my 14.8 volt / Basic 4200 / UF setup with graphs similar to what was reported on the 12L3 thread.

Although your theory about brushless setups seems to be good, I would really like to see how it translate in "down to earth", real world of racing. Brushless r/c car are still very intriguing beast to me and we don't really have a lot of knowledge on them.

I like the way you think and the fact you do have a lot of BL brushless knowledge.

Only I am still slightly skeptical on how the theory will apply to our use, because it is mostly on/off throttle and only very little wot/top speed which makes it difficult to know exactly what's happening while driving.

Stuff that apply to boat or aircraft are off no use for us.

Once upon a time **sight** there was a guy named OptimaMan on this forum. He was one of the most experienced guy in here.

He had tried A LOT of BL setups on r/c cars.

His theory, although similar to yours, was that lower wind motor / high voltage is key, but he was also saying that low ratio and being very close to motor max rpm are things to consider.

I'll be interested to see what you think of his theory, read here:

http://www.radiocontrolzone.com/forums/showthread.php?t=160008

Anyway, sorry for the long post !

DFF

[bomb-proof]

An XL in a TC3 would not be the best choice. The bigger motors run better on higher cell counts, and 8 cells isnt a high cell count. The correct motor for the application will fit perfectly and will be more power than you need. Plenty of motors to choose from that will fit that criteria, bigger is not better.

[FninjaP90]

Okay, I guess the Basic 2700 then. Save me a few bucks too.

[studysession]

Okay, I guess the Basic 2700 then. Save me a few bucks too.

I missed something. Why the 2700 and not the 5300?

[FninjaP90]

I missed something. Why the 2700 and not the 5300?

According to AndrewG, "slower" motors are more efficient than "faster" motors given the same wattage.

So in that case, I should change the 14.8V 3000mah 4s2p pack into a 29.6V 1500mah 8s1p pack for greatest efficiency, but since there is no controller this side of the Schulze 40.160 that can handle the voltage, that's ruled out.

But what about an 18.5V 5s2p pack? Are there any ~$100 chargers that can handle 5 cells in series and can do NiMH and NiCd also?

I know that efficiency is important, but to me, so is RPM. If I run a Basic 2400 with a 14.8V pack and get great efficiency but only 35k RPM, the most I could get out of a TC3 with highest possible 5:1 FDR is maybe 45mph. A 14.8V 2400 is also only putting out about 450W, according to Lehner's graphs.

I want to be more flexible than that. I want my car to out accelerate all the cars at my track, but also be able to do 80mph.

Man, finding the right combo for brushless is way harder than doing it for brushed motors...

[studysession]

OK - I didn't miss anything then. It also depends on application. I have been using the Lehner Basic 5300 in my TC3. I have others that I use. But I like the performance of the 5300.

[Andrewg]

Daff

First off the way to select a motor for a car is the same way you would for a plane or boat. Figure out the amp draw you are going to run at or the runtime you need. You then pick a motor with it maximum efficiency at the voltage and amp draw implied, so you can get maximum speed. In boat racing we run far higher power than cars. In drag racing we run 110amp loads and in F5D pylon and F5B glider amp draws of 130amps are not uncommon.

Optima mans theory is fine in as far as it goes. What he doesn’t mention is that a motor that’s great on say 6 cells and gives the runtime cant be put onto 12 with a higher reduction – because the extra voltage will change the motors maximum efficiency point - it will move it up. At the same time it will usually reduce efficiency at the amp draw you need to make the runtime.

Ninja

I didnt mean you to understand that lower rpm motors are more efficient at high outputs. Most electric motors are more efficient at higher voltage, but for a given motor the amps at which it is efficient will be higher too. So if you want motor to run at max amps that will allow you to make your runtime and run efficiently you must increase motor resistance and reduce amp draw at idle (effectively I am saying add a few winds) which also lowers rpm/v.

And rpm is not important unless it delivers higher horsepower or high torque.

Here are three examples which illustrate what I have been talking about and they change my mind about which motor will work best for you - assuminmg you would like to be able to make a 5 minute race time.

#1 Run 7.2v pack 4500 mah capacity you want 5.4 minutes runtime or 50 amps average draw . The closest Lehner basic is the Basic 5300 which at 7.2v runs max efficiency of 83% at 51amps and 8.6Ncm torque at 33984rpm.

#2 Run 14.4v pack 4500 mah capacity you want 5.4 minutes runtime or 50 amps average draw. The closest Lehner Basic is the Basic 3100 which at 14.4v runs max efficiency of 86% at 49amps and 12.8Ncm at 41884rpm.

#3 Run 14.4v pack 4500 mah capacity you want 5.4 minutes runtime or 50 amps average draw. The closest Lehner BasicXL is the Basic 2400 which at 14.4v runs max efficiency of 92% at 48amps and 16.6Ncm at 19855 rpm

Gears can equalise output and affect torque to increase or reduce accelleration - equalizing the rpm will reveal the best performance option

#1 = 304w; 19855rpm; 14.72Ncm torque; 5.4 min runtime
#2 = 606w; 19855rpm; 27.00Ncm torque; 5.4 min runtime
#3 = 636w; 19855rpm; 16.60Ncm torque; 5.4 min runtime
#B4200 = 936w; 19855rpm; 36.26Ncm torque; 2.2 min runtime

Clearly the 4200 wouldn’t be a 5 minute race option because of its amp draw at max efficiency at 75 amps and only 87%; and if you run it at a lower amp draw even worse efficiency and less power.

But I just changed my mind on the best motor. The Basic 3100 looks very good on 14.4 if you want a 5.4 runtime it will give you the best acceleration of all motors and speed equal to anything except the 4200 which may be red hot and loosing parts at 60000 rpm.

With 603 watts, if a 280w modified can run 50mph a 1/10 car with the 3100 could run 64mph.

In those calcs I resorted to an average amp draw. But a short twisty circuit will see you accelerating hard moroe often so increasing your amp draw. A long smooth oval will mean lower amp draw.

There is another way to get a more accurate picture of what is right for your track or style of driving. Get an eagle trees telemetry system and plug it into your car. I will give you rpm, current draw motor temp voltage speed steering direction all on a dashboard like readout on your computer – the best $140 you ever spent and your friends will go berko when you let them use it.

It will tell you what amps you are really using and which parts of the track you need to pick up speed or acceleration. This will let you really hone your motor pic and the advance and gearing you use. The readouts leadsto very fast understanding of whats happening, and let you see how your mods affected the car. The end result is much better performance much sooner. Much more effective than a billion dollar motor or a pack of super cells.

And the other guys will want to use it so you pick up their setups for comparison wth your own......

[DaFF]

Andrewg,

It seems to be an interesting theory, but IMHO cars BL doesn't act as boat or plane.

Boats and planes run often at wide open throttle, while I don't see doing a wot in car for more than 2/3 sec. A car on a race track is mainly accelerating / braking.

It might just be me, but my past experience with nitro and electric cars have always told me that short gearing is a key element in having a very reponsive cars without too much heat and the main thing about having a short gearing is that it greatly reduce stress on transmission pieces.

If you look at any brushed car recommended Final drive Ratio, you'll see that the lowest wind brushed motor are always run with extremly low FDR.

I can also tell you that my Lehner 4200 and UF does not suffer from getting 14.8 volt from my batt. I have checked my temp on both of them and none of them were out of temp range, nor did I needed to add extra fan or anything on them.

Anyway, my Eagle Tree system is already on order and I should be able to give true measurement soon - BTW, add 40 US$ to your 140 US$ because you need the optional electric wiring to be able to record pack voltage and Amp draw -

I might try a Lehner 3100 Kv with my current setup ( UF and 14.8 volt Lipo ) later on and we will see what the numbers will says. Depending on the result, I might end-up using the 3100 over the 4200...

DFF

[FninjaP90]

AndrewG, I understand your steps to finding the right motor is:

1) Decide the amps you want to draw from it
2) Find the motor with the best efficiency at that voltage and amp draw

If I were to use a 3000mah 15C-max 10C-constant LiPo pack, then should I decide on a motor whose max efficiency is at 45A or a motor whose max efficiency is at 30A? Which one is on the safe side? What limits the motor from pulling more than 45A? Does the controller limit this somehow? What keeps the motor from drawing more amps than the LiPo pack can handle and setting the car on fire?

[Andrewg]

DFF

like I said they all act the same way - but I am using an averaged number.

And yes electric cars do use low ratios. I have found their transmissions tend to give up with hi-torque. A lot of guys converting prefer nitro transmissions simply because they dont crack up.

I agree entirely with what you said about acceleration and the lower Ir motors will have a fatter midrange because they pull more amps too.

Finally if you are racing you will be using throttle management. Fninja didnt say he was racing. Maybe I am a nutter but when sport running I only use flat out....?

What chassis and cell combo do you have the 4200 in? What is the all up weight.

I think your feedback with the eagle trees will be interesting and very helpful. It will clarify the throttle position and amp draw relationship. I hope you can publish some data on here. Video withthe dashboard patched on the bottom makes for a very quick learning process as to awhat is happening.

FNinja

in the examples I gave the motor will spend any time acccelerating at WOT at more than 45 amps - it will hit 45 amps when it winds out to top speed.

It will pull less current if you use partial throttle.

The peak amps would be around 60ish with maybe 150 stall amps.

Are you going to race this or use if for mucking around?

[FninjaP90]

I'll probably both race it and do high speed runs.

What do you mean peak amps and stall amps?

[Andrewg]

OK I assume you want a good race motor which you will then tryout in terms of seeing how fast it will go?

That means you need a motor which has good efficeincy (more power) over a broad range of amp draws, but is biased toward higher amps - power everywhere...

Rather than great efficiency only at very high amp levels ... topend power

Peak amps and stall amps are the smae thing - if you apply a voltage to the motor then stop it by putting the shaft in a vice - it will be stalled and it will pull the most amps it will pull in any situation at the voltage you apply. This amp draw is known as stall amps and it is the motors peak amp draw.

[DaFF]

What chassis and cell combo do you have the 4200 in? What is the all up weight.


Chassis: HPI Pro4 - It's a full option, high end, extremly light, carbon fiber, 1/10 scale, shaft drive 4x4 chassis.

As said, the motor is the Basic 4200, the esc is the UF-75.

So far, I've tested 2 Lithium batt:

- PolyQuest last gen High Discharge PQ-B2600-HG 4S, that's 14.8 volt, 2600 mA batt with 10C continuous and 15C peak ( less than 10 sec ).
It translate into 26 Amp continuous and 39 Amp peak under 14.8 volt

- Flight Power "Extreme Kapton" ventilated pack, I used 2 x 7.4 volt 3200 mA in serie. They are rated at 10.5C continuous 14C peak, translating into 36 Amp continuous and 44.8 amp under 14.8 volt.

The Ready To Run, total weight with body on is 1.255 kg, which is extremly light for a 1/10 scale - way under the 1.500 kg minimum racing weight -

Temperature on my system under race condition
esc : around 70 deg C or 158 deg F max
motor : around 75 deg C or 167 deg F max
batt : around 45 deg C or 113 deg F max

I also have the PC link and did setup the max rpm to 65 000, the low voltage cut-off to 12 volt to match with my lipo batt.

I did not yet play with other parameters, but my goal is to wait until I have the Eagle tree to see exactly what parameter affect Amp draw, motor/esc/batt temperature, speed and accel and I'll try to quantify them to have my UF parameter set the way I want.



I think your feedback with the eagle trees will be interesting and very helpful. It will clarify the throttle position and amp draw relationship. I hope you can publish some data on here.


I'll sure keep you all posted. You'll see screen grab of my UF setting and Eagle Tree system.

I have a business laptop, which will be very helpfull to have at the track.

That will be instant information and will speed-up the process of finding the right gearing and UF setting.


Video withthe dashboard patched on the bottom makes for a very quick learning process as to awhat is happening.

??? sorry, I didn't get this last bit LoL


DFF

[DaFF]

Second pic...

DFF

[DaFF]

At the track...

DFF

[studysession]

Nice pics.

[Andrewg]

Daff
a very nice setup! lovel car. BTW what advance do you use?

So the peak amps the packs want to operate at is 46 amps? If they are the kokam 15c cells at 15c the voltage is a little down and the discharge curve goes low then recovers in the latter part of the run - have you noticed anything like that? Not a big effect but noticeable

ok from the lehner charts here are some extrapolations
* the 4200s peak efficeincy at those volts would be at about 65 amps
* the 4200's efficieny will be in the 90-92% range and putting out less than 3 watts per sq cm which with an airstream would ensure it stays cool - as a rule of thumb 0.5 watts/sq cm in still air and the motor can run indefinitely (that will vary with the temp)

Using the lehner figures and a calculator the efficiency on the 4200 is high over a very wide power band at this sort of votage - which is near the limit for these motors. it holds up past 130+ amps better than the 3100 but has a little less efficiency between about 10-15amps. So regardless for both motors the efficiency has hit the motors ceiling and is high enough that the range is really only different at levels of amps you may not be using when racing (at the top end and the bottom end of the scale)

the 3100 looks to have the same max efficiency but at 46 amps a lot closer to the specs for your packs. (it will be interesting to see how much they can put out for .1-.5 secs).

The one concern I had was the Lehner curves were very close to the motor calculator. This makes me ask has Lehner dyno or calculated the info on its pages?

My guess is there would be almost no noticeable difference between the 4200 and 3100 in a 1/12 or 1/10 in many applications except say oval vs very tight track.

Now I am really looking forward to your results - to see what is happening on a micro level and whether the figure are anywhere near what Lehner claims.

[DaFF]

Hi andrew,

For the timing of my U-Force esc, I don't know.

As for my batt being on the edge and taking some time to recover, I have never experienced anything like that. Those Lipo seems to be strong current wise because the power is unbelievable and it doesn't seems there is any big drop of voltage, even under hard condition.

Mind you, my gearing is as short as I can make it, the 24 pinion on 94 spur lead to a very low FDR of 9.55 ( calculated top speed 52 mph or 82 kph, that's way less than this setup can take ! )

I've seen that the Lehner curves and graphs are usually done under 15 deg timing, but the U-force has only 4 timing that they call:

Timing 1: Hard ( optimum on Ikarus, Koller, LRK, Plett motor ) for max rpm

Timing 2: Medium ( optimum on Aveox, Kontronic, KBM motor )

Timing 3: Soft ( optimum on Astro, Aveox, Bittner, Hacker, Kontronic, Lehner )

Timing 4: Super Soft ( optimum on Hacker, Kontronic, Lehner ) for maximum run time.

I have no idea on what is the actual timing value hiding under those "Hard / Medium / Soft / Super Soft" setups.

To tell you the truth, I did not yet play with those setups, I let the UF select the timing by itself, when it start.

I'll see later what it does on my volt / Amp value.

For the peak Amp, I would like it to be under 40 Amp because I have ordered another PolyQuest batt and this is the peak Amp it can take.

Talking about your calculations, what I don't understand is how the 4200 can draw 65 amp under 14.8 volt ? That's 962 Watt, way over the 700 Watt I was told the 4200 can take....

I was under the impression the max Amp the 4200 can draw would be 47.3 Amp under 14.8 volt ( 700 Watt ) ????

Anyway, from what I can say about my tests, the average amp draw on my car must be very low because I know for a fact I can drive more than 12 minutes on racing condition with my Lipo 2600 mA pack before it needs to be charged ( and that's being conservative because I did not go up to the last drop of power, my batt voltage was still well over the 12 volt minimum for a 4S-14.8 volt batt )

I guess your calculations are based on continuous operation, at max power or very close. I think you can double or triple this number because even under race condition there is parts of my track where I am free whelling i.e. not applying any power to the car.

For example, after the long straight, when I am at full speed I do not apply any power until the next curve which is a long way ( probably around 20 meter or 65 feet ).

L8ter

DFF

[FninjaP90]

Daff,

When I took in account your 9.55 FDR, your calculated top speed of 52mph, and the fact that at 14.8V, the 4200 spins at 62160rpm, I figured out that the tire diameter figure you plugged in is 2.69". How's that possible? Aren't TC tires 2-2.25"?

AndrewG,

So what you are saying is that if I go for the 14.8V 4500mah 15C capable pack, that I should get the Basic 4200, and that if I go for the 14.8V 3000mah 15C pack, that I should go for the Basic 3100, since both of the motors' max eff. spots are at the highest amp current the battery can supply.

But what if, for example in the 3100, the motor pulls its peak current of 60A? Or its stall current of 150A? What can I do to prevent drawing too much current from the LiPo's if the motor hits the peak or stall amperage?

Also, how much do normal brushed 540's weigh? And how much shorter are the Lehner Basics compared to normal brushed 540's?

[studysession]

:o OK - I feel like an idiot asking this - but how are you calculating speed and how many amps you are drawing from the batteries?

[FninjaP90]

Well, the batteries I was talking about have a 10C constant and 15C burst amp rating. That means if the battery has an X amp hour capacity, then it will be able to supply 10X amps continuous and 15X amps burst. So if we are talking about a 1000mAh, or 1Ah pack, then it will be able to supply 10A constantly and 15A for a short amount of time.

For his speed, he is going 52mph. That equates into 3294720in/hr. Which is 54912in/min. His motor is spinning at 14.8V*4200=62160rpm. Divide that by the 9.55:1 FDR he is using, and he is getting a wheel rpm of 6509rpm. To get 54912in/min with that many rpm, you divide the wheel rpm by how fast he is going to get 8.43in/revolution. Divide that by pi(3.1416) to get his wheel diameter of 2.69".

Figuring out mph is just doing that above problem backwards.

[Andrewg]

Daff

the ratings for those motors are nominal – safe operation in relation to heat and rpm. I am not sure how long you could keep it running at those power levels. But – the F5B glider pilots use a Hacker B50-8L on 26 cells 7:1 gearbox and run huge props which put 2600 watts into the motors for 10-15 secs. And the motors are fine. Similar resistance level to the 4200.

Usually the default setting for controllers is the lowest advance – ensures the motor runs at maximum efficiency. And if the controller has continuously variable timing it should be running in the lower end of advance. If you wanted insane speed run power you would go timing 2 for racing 4 and 3. You can see if you used a 4 or high pole motors like some pletts you would use 1 3 and 2.

Your figures for runtime and pack capacity indicate you are averaging a maximum 12 amps average. Even if your tripled its 36 amps. The efficiency at that current level should be as good as it gets but you will be at that part of the curve where a lower amp draw will see efficiency dropping rapidly. As torque is proportional to current, it will be around 50-60% of what I calc’d for the 4200 at 60+ amps. Perhaps that is a blessing?

It also explains why cars can run a S series motor whereas a boat pulling the same amps would use an L in European racing (5&6 minute races) and in USA (5 lap sprint) they would use an XL and a motor with 1900-2100 rpm/v – they need the torque.


FNinja

re the motor wait till you have DaFF’s feedback – it looks to me like a low kv motor may be the way to go for a nitro car if the amps are as low as I am speculating as the torque will be better and I imagine the nitro drive train is a bit heavier a with a little more drag.

When you accelerate as hard as possible the motor will hit very high amps – for very short periods – cells motors and controllers can generally cope with this. As the car accelerates the amp load drops its when those loads are maintained for long periods of time and that usually only happens when the gearing is too high or something is jamming the driveline

Normal brushed 540's weigh about ½-1 oz more than the Lehner Basic. It depends – the better modifieds tend to be heavier.

Also the 4200 isnt going to spin to peak rpm in the car. The pack voltage will be closer to 14v under load and the motor will spin to about 89% of the peak rpm at that voltage. See if that fits better with the tire size you anticipated.

[DaFF]

FNinja,

Here is my calculation for estimated theoretical top speed on my car:

The given are:

Primary ratio = spur gear number of teeth / pinion number of teeth
Pr = 94 / 24 = 3.9167

Secondary ratio is fixed, it the differential gear ratio which is:
Sr = 39/16 = 2.4375

Final Drive ratio = Primary ratio x Secondary ratio
FDR = 3.9167 x 2.4375 = 9.5469

It means that if my motor is 65 000 rpm, then my wheel are spinning at:
Wheel rpm = Motor rpm / FDR
Wrpm = 65 000 / 9.5469 = 6 808.5 rpm

Given my wheel od of 64 mm ( or 2.52" ), my wheel perimeter is:
Wheel Perimeter = Wheel OD x Pi
Wp = 64 x 3.14 = 201 mm ( or 7.91" )

Since my wheel is rotating at 6 808.5 rpm and it does 201 mm for each turn,
my speed is:
Speed ( in kph ) = Wrpm x Wp x 0.00006
Skph = 6808.5 x 201 x 0.00006 = 82 kph

Note: 0.00006 is the conversion from millimeter to kilometer and minute to hour

To convert from kph to mph, I used the following formula:
Vmph = Vkph / 1.6 = 82 / 1.6 = 51.3 mph

So, it means that if my motor is running max rpm ( 65 000 ) then my car goes 51 mph ( or 82 kph )

As for my rpm, from the feeling I have, I think I am hitting max rpm at the end of my track when pack is fully charged because:

- The 4S - 14.8 volt lipo is 16.8 volt fully charged ( that's 4.2 volt per cell )

- Under 16.8 volt, my motor could spin 16.8 x 4200 = 70 560 rpm ( but of course, there will be a drop of voltage, thus a drop of rpm under load )

- 65 000 rpm means my voltage goes down to 15.5 volt, I guess a drop of 1.3 volt is possible ( look at the 12L3 lipo voltage pack, you'll see that under 80 Amp, the Lipo loose around 1.5 volt )

- I can feel my U-Force esc is regulating the rpm to the set value of 65000 because it doesn't seem to go any faster at the end of the straight, even under full throttle ( when pack is fully charged )

So my guts told me I an pretty close to 50 mph with this setup, but with the Eagle Tree, I'll get a definitive answer since there is a rpm sensor...

---------------------------------------------------------------------

Talking about motor weight, my brushed 17 turn motor is 170 grammes ( or 4.5 oz ), while my Lehner 4200 is 145 grams ( 3.83 oz ) which confirm what andrewg said. Lower turn brushed might be heavier, I don't know ?

My 17 motor can is 55 mm including the brushes while my 4200 is 40 mm.

Also, be carefull with the weight of lipo pack, because my 2600 mA 14.8 volt is 210 grams ( or 5.55 oz ).

A 4500 mA 14.8 volt will be around 380 grams ( or 10.05 oz ).

A 6 cell Nimh 3300 pack is 360 grams ( or 9.51 oz )

It means that you will face severe problems of right / left unbalance because you will shave weight on the side where the motor is, but will add weight on the battery side.

Furthermore, lipo pack are usually wider than regular NimH pack, which will mean more weight, further from your car main central axis, which will aggrave your right / left side unbalance !

Time will tell and true number will come, I can't really comments on the 3100 versus 4200 motor because the gearing will not be the same at all.

But I'll see, maybe andrewg is right and the 3100 might draw less Amp and be more easy and forgiving for the Lipo.

One thing for sure: I don't want to loose the accel and top speed I am already getting with my 4200 !

We shall see :)

L8ter

DFF

[FninjaP90]

Daff, I've had balancing in mind all along. I don't really know which car to pick. Since I've had a TC3 already, I'll probably go with something new, maybe a Pro 4 just like you. Sorry to copy you so much.

According to my calculations, there should be enough room on the motor/servo side for another group of cells in between the motor and the servo, since the brushless motors are 15mm shorter than the brushed ones.

I'll put in a 14.8V 4500mah 4S3P pack, a Basic 4200 (Since the batteries can provide the 60A for the 4200's max eff. point), and stick a Lehner 7018 on the top chassis brace.

I'll put the reciever on top of the front bumper to minimize electrical noise and the 40g 6V 2/3AAA receiver pack either inside the bumper or somewhere in the middle of the body.

Each 1500mah cell weighs about 31g, and I'll be sure to add some aluminum plating or some other reinforcements around the cells, and that'll add about 10-15g per group of cells. My setup will weigh about as much as a brushed setup with 7 cells. The front left/right quadrants will both be about 120g each, while the rear left/right quadrants will be about 200g each.

Either this, or a 18.5V 3000mah 5S2P pack and a Basic 3100 if I can find a 5-cell capable charger cheaper than the AstroFlight 109. Rebalancing the chassis should be easy. It'll also make it weigh as much as a normal brushed 6 cell setup.

[TheSteve]

DFF,

I don't think you're hitting the RPM limiter in the U-Force - you'd know if you did as it generally knocks the RPMs down quite a bit and then bring them back up a little. Its really not that smooth. I tested the RPM limiter by setting it quite low and it was always very obvious when it kicked in.

[Andrewg]

I would use 3.5v per cell under load even - even the 20C Kokams go down to 3.45at 15c.

Also the motor should top out at 87-90% of peak rpm - if you go past that rpm the falling current and rapidly falling efficiency mean the motor power is low.

[DaFF]

Fninja,

I think you are really optimistic about putting that much cells on a TC3 or Pro4.

What are the size of the cells you've put on your drawing ? Did it takes into account the tabs and the wires connected to it ?

Because there are things you didn't take into account, like the size of the wires and how you will strap down the batt and other stuff onto your chassis.

BTW, between my Lehner 4200 and my servo, there is only 85 mm left...

Don't forget also that the front left space is already taken by the steering linkage which need to rotate freely ( that's another 25 mm less space up front left, it's 25 mm less from the linkage post )

You'll have to use a low profile servo for sure and a tiny receiver and I think you'll have to forget about the receiver pack also, using a U-Force there is no need for one.

FYI information, I am already using mini size servo on the steering, it is a Hitec 5245MG which is way smaller than any regular size or even low profile size servo. It's holding up good so far and it's fast enough and torquey enough on my Pro4.

I also plan to use a micro size receiver, I've ordered an very small Jeti Rex 5 plus. I know it doesn't go as far as a regular size receiver, but It should be enough at my track. Since the Eagle Tree system count the receiver glitch, I'll be able to tell if this is a viable solution in my car.

Anyway, good luck on your project.

The Steve,

I was under the impression I was hitting max rpm, but since you said it knock-off the rpm, I guess I was wrong !

Andrewg,

it seems you are right again about the max rpm, I can't wait to have the eagle tree system hooked-up to know for sure the rpm, volt and Amp value !

Thanks all for the replies :)

I'll keep you posted

DFF

[FninjaP90]

Daff, I've had everything figured out.

A bare 1500mah Lipo cell is 42mm x 69mm. In my scale drawing, to adjust for wiring and tabs and aluminum plating and stuff, I showed the right side pack as being 45mm x 75mm and the big left side pack as being 45mm x 147mm.

I don't think it will interfere with the steering linkages since the big pack is only 13mm longer than a standard 6-cell SubC pack. You had one of these packs too, remember? Your 14.8V 3000mah 4S2P Powerflight pack.

Don't worry, I have the wiring schematics drawn out too.

As for battery brace towers, I'll just drill some new holes and relocate them. I'll buy a new set for the right side batteries. For the battery braces themselves, I'll just make my own out of plate aluminum, and probably get them hard anodized or something.

I know that I don't need a receiver pack, but I think it would be more efficient if I did. Normal 6-SubC setups don't need a receiver pack since the ESC's BET only has to burn off 7.2V(from battery) minus 6.0V(to receiver), or 1.2V. But for our 14.8V setups, the BET has to burn off 14.8V-6.0V=8.8V. Which is very inefficient. It would be better to just put in an extra receiver pack.

Your HS5425 is 8mm shorter than a normal servo. Your 85mm-8mm=77mm. I'm figuring that my battery pack would probably end up around 75mm, including all the wiring, bracing, etc. If it doesn't fit, then I can get a HS5245 like you or a Futaba S9550, which is a 83.3oz-in, 0.11s standard sized digital servo that's even 10mm shorter than the HS5245.

Also, why are your PolyQuest cells double shrinked? Why don't they have open spaces in between the cells for air to circulate around them and cool them, like your PowerFlight cells?

AndrewG, is a 14.8V 4500mah 10C-constant 15C-burst pack too much battery for the Lehner 4200?

[FninjaP90]

Hmm, other than more runtime, will the 4s3p pack give more noticible performance with the 4200 than the 4s2p pack with the 3100? How much will the car's handling suffer with an additional 130g from 4 cells? Daff, since the 4s3p car will weigh about as much as a normal 6-SubC car, do you notice a drastic difference in handling when you compare your car to a normal 6-SubC car?

Either I save $60 per pack and shave 130g off the car and sacrifice some pure speed and runtime, or I can go balls to the wall with the 4s3p pack at the sacrifice of some handling. This really is a hard decision.

[Andrewg]

Ninja

4500 mah is fine - the amp draws will average about 5-8C - altho the short term peaks might be 15-20C for a couple of seconds

So the car should run all day (almost)

The 4200 looks too hot but I am going toward the view that I would would like to see what Daff gets with his telemetry.

the amount of time the car speeds accelerating and the load will be important - then we can figure out short term loads vs the avergae laod and maybe get a better idea of which motors match up best

[DaFF]

FninjaP90,

1- Good thing you checked for wiring.

I still think it is going to be hard to swap battery with your setup, you'll need a lot of batt connectors, but I guess it is feasable.

2- As for my PolyQuest cells layout, it is not at all the same layout as my FlightPower layout. The flightPower is a vented type layout were there is pads that act as shims in between each cells, allowing for air flows in between them. I guess it is a better layout than the Polyquest because it allows to cool them better.

On the other side, my PQ pack has foam in between each cells and around them, which make them less prone to get damaged. Furthermore, the PQ is more compact, it feel like a brick and is off less height, good for a better lower CoG. I do like the extra protection ! ( the flight Power can be very easely damaged... )

Each PQ and FlightPower packs has it's Pros and Cons !

3- I have never tried subC cells, only regular size Nimh 3300 Batt...

4- Anyway, for my batt bracket, I'll be using a thin 1.5 mm carbon fiber strip ( but I guess an alum strip would do the same function )

I'll be using double sided tape to have the batt linked to the CF strip and I will use some high strenght tape to secure the batt on them.

Note: In order to avoid same problem I had previously with too much pressure on the batt tap, my securing tape will only be on the side of the batt, but strapping it along the WIDHT ( and not along the lenght as shown on my pictures ). I'll be also very carefull not to put too much tension on the tape !

This strip will be the same widht as my batt, but slightly longer to accomodate for 2 holes dia. 3,2 mm.

The strip will then be bolted onto my chassis using 2 M3 screws and nuts.

It's light, simple and yet will allow me to swap batteries easy, just by unscrewing the 2 bolts ( For now, I'll have 2 identical batt attached to 2 CF strip ready)



Andrewg,

Tower listed my Eagle Tree system order as being shipped today.

If I am not caught by the french customs :rolleyes: it should be at at my doors within 10 days.

If I am caught by the custom, then it might be 20/25 days :mad:

I'm crossing my fingers, like I do everytime I place a tower order !

L8ter

DFF

[FninjaP90]

AndrewG,
Wow, if it does normally draw 5-8A, then a 4500mah pack will last for 30-50 mins. Do you even think I will need a second battery pack?

Daff,
The usual nimh cells everybody uses are SubC cells. GP3300's are SubC cells. SubC is their size denotation, just like AAA, AA, C, D.

Why would it be hard to connect the batteries together? I already have a drawing of how I should arrange the wiring so that it just has one plug, like a normal 6-cell SubC pack.

What problems did you have with your battery brace? Did it damage the batteries somehow?

[Andrewg]

Fninja

5-8C not amps - thats 22.5-36amps

Daff this shoudl be interesting - i hope the customs gods smile on you.

BTW do you have any other brushless motors?

[Quinton]

I don't know a thing about brushless motors, but I am thinking about getting an e-sedan. I am wondering if I should get like a 9 or 10 turn brushed motor or a brushless system? What is the pros/cons of brushed vs brushless? If I were to go brushless I would only want to run 6 or 7 cells. I know I've heard of cogging when you don't feed some brushless systems enough power (I guess that's what it means)

What kind of speeds would I be looking at with those 2 different setups? roughly
Thanks

[Andrewg]

Hi the brushess will be more expensive it will deliver more power everywhere run cooler and often run longer. The power band is wider and more linear than a brushed motor. You dont need to maintain it.

Cogging is a specific electrical characteristic and it isnt noticeable.

What is noticeable is that the start up is not quite as smooth as a ferrite motor. This is to do with the electronics having to look for the rotor position then correctly fire the coils. Older controllers were easy to fool and the motor would stop. Newer controllers are much better - Schulze and Hacker.

The effect vanishes once underway.

For 6 cells the Lehner 1920 and Hacker B50-s series look good. The Lehner 5300 looks pretty good and value and the Nemisis/Feigao motor is nto quite the performer but is very inexpensive - Schulze U-force or Hacker Master Car are very good.

Dont go cheap or underrated on the controller. Unlike a brushed motor a brushless can pull big amps if you lock it up with a bag or a stick in the wheels.

[FninjaP90]

So a 14.8V 4500mah 4s3p pack wouldn't burn up the Basic 4200? Will the Lehner 7018's 70A limit be safe for my setup, or should I go higher?

[Andrewg]

No way - brushless motors are very efficient and run cool - not cold but the heat isnt localised like it is in the brushes and comm and the windings in a brushless have less iron and so lower iron losses than a 05 - all in all they run much cooler.

With longer runtimes - just gear it down a bit or direct more air to the motor.

Your controller is the weak link - almost always regardless of make - make sure it is LiPo compatible or you will over-drain your cells.

[bomb-proof]

For 6 cells the Lehner 1920 and Hacker B50-s series look good. The Lehner 5300 looks pretty good and value and the Nemisis/Feigao motor is nto quite the performer

I have run all of those, and they are all very comparable. The lehner motors maybe have the slight edge, but it may have just been the rpm/v difference, but probably the highest quality finish on the motors. I still dont know why you keep saying the Feigao motors are "not quite the performers" . Its obvious you dont like the motors for some reason, but have you ever run one? Sorry, I just had to bring that up.. I hate to see a product bashed so heavily that works so well. Is this all based on theory?

Which one did you run, what cell count, and what vehicle? I have yet to find one that has shown a noticable differance than any other BL motor.



I wouldnt do 4s3p on a 4200. If you want massive power, get the right motor for it, not the cheapest. The 4200 would be pushing it in my opinion on 3s3p, but I dont think it would be a problem. Its a pretty simple formula for choosing the motors, just look at thier recomended cell count, and follow that. Stray from that and you are heading down a smokey road.

[Andrewg]

Why do i keep saying Feigao motors are "not quite the performers" and is it obvious you dont like the motors for some reason?

I think they are a bargain. But I have also seen the dyno results for the b20's and b40 sized motors and they just dont have it. In terms of efficeincy torque and amp handing they are down. Plus they have some issues with iron losses.

Have I run one no- but clients and racing colleagues have. They say they are great - you dont notice the difference in sport use.

I am not bashing them. But I say what I know to be true ie against the clock and on the dyno they are not as good.


As a dealer for Hacker and Mega and my own Neo brushed motors for boats cars and planes for more than 4 years I have seen and used a lot of motors
I also drove the development of the Hacker Navy controller and tested the beta car controllers which were a navy controller - with modified software and casing.

I believe the reason the difference in cars is not noticed is because brushless setups in cars generally seem to underestimate the capabilities of brsuhless motors.

I have explained the shortcommings of the 4200 other lower kv motors are better suited.

[Andrewg]

oh and i forgot i have recently made enquiries about distributing feigao (aka nemesis, himaxx et al - so I cant be that down on them

They have their place they are very inexpensive and perform well in a sport role. Their Io's are higher (iron losses again) than is ideal for cars and the performance envelope a little more limited.

But hey I also run some power tool motors not cause they are the most efficient or powerful but because they are cheap fast and fun performers.

[studysession]

Anyone have a link to the feigao motors?

[starluckrc]

I am a US distributor to several dealers. Specs are on my site.

www.starluckrc.com

[Andrewg]

http://www.feigao.com/

[studysession]

http://www.feigao.com/

Thanks.

[FninjaP90]

Oooh, Feigao is Chinese. I should have caught on that earlier. Well that makes sense. I always thought it was Italian or something. Feigao = fly high in Chinese.

[johnrobholmes]

thought i would throw in my 2 cents

i have tried a few brushless motors in my tc3. a lehner basic 4200 and a basic xl 5000. the 4200 was pretty sick. fast on 6 cells, much faster than any brushed motor i have ever owned. the xl 5000 was more than the car could handle on 6 cells(or was it me?) torque steer was noticable, acceleration was very insane, brakes were instant and crazy, and i was much too afraid to get it up to top speed. i just dont know how to set up that car properly. the only problem that i had with the basic xl 5000 is that it tore up my ball diffs front and rear. so much torque. i guess the top speed would be above 70 if i didnt chicken out before i hit 65. im into crawlers and trucks, not a road car buff.

anyway, i would suggest a 8s hacker or feigao for the tc3, or a 5300 lehner. if you want to get crazy, go with the basic xl can or a L can hacker/ feigao.

the tc3 is so light that you dont need a motor that spins slow and needs high voltage to keep the heat down. stay around the 5000 rpm/volt range and itll preform well on 6 cells- in my experience.

[mac0326]

thought i would throw in my 2 cents

i have tried a few brushless motors in my tc3. a lehner basic 4200 and a basic xl 5000. the 4200 was pretty sick. fast on 6 cells, much faster than any brushed motor i have ever owned. the xl 5000 was more than the car could handle on 6 cells(or was it me?) torque steer was noticable, acceleration was very insane, brakes were instant and crazy, and i was much too afraid to get it up to top speed. i just dont know how to set up that car properly. the only problem that i had with the basic xl 5000 is that it tore up my ball diffs front and rear. so much torque. i guess the top speed would be above 70 if i didnt chicken out before i hit 65. im into crawlers and trucks, not a road car buff.

anyway, i would suggest a 8s hacker or feigao for the tc3, or a 5300 lehner. if you want to get crazy, go with the basic xl can or a L can hacker/ feigao.

the tc3 is so light that you dont need a motor that spins slow and needs high voltage to keep the heat down. stay around the 5000 rpm/volt range and itll preform well on 6 cells- in my experience.


Th hacker/feigao s can is VERY similar to the lehner basic xl in terms of size/power etc.. The 8s is somewhere between the xl4200 and xl5000. I wouldn't recommend a hacker/feigao for a tc3 unless you plan to secure the endbell mechanically(and I am a dealer for Feigao). I drill/tap the endbell and put small screws to secure the bell on my motors. In my tc3, I run a 4200 with 11.1 volt li-po cells. I find the 4200 slow on 6 cells, but it FLIES on 11.1 volts! The ball diff problem you had is most likely due to poor/improper adjustment. I have yet to have diff isues on 11.1 volts. The xl5000 is probably an excellent choice on six cells, or the basic 5300. I know the 5300 on 7 cells is pretty fast. The Hacker c40 series motors work well, too(fixed endbells vs the b series).

[mac0326]

thought i would throw in my 2 cents

i have tried a few brushless motors in my tc3. a lehner basic 4200 and a basic xl 5000. the 4200 was pretty sick. fast on 6 cells, much faster than any brushed motor i have ever owned. the xl 5000 was more than the car could handle on 6 cells(or was it me?) torque steer was noticable, acceleration was very insane, brakes were instant and crazy, and i was much too afraid to get it up to top speed. i just dont know how to set up that car properly. the only problem that i had with the basic xl 5000 is that it tore up my ball diffs front and rear. so much torque. i guess the top speed would be above 70 if i didnt chicken out before i hit 65. im into crawlers and trucks, not a road car buff.

anyway, i would suggest a 8s hacker or feigao for the tc3, or a 5300 lehner. if you want to get crazy, go with the basic xl can or a L can hacker/ feigao.

the tc3 is so light that you dont need a motor that spins slow and needs high voltage to keep the heat down. stay around the 5000 rpm/volt range and itll preform well on 6 cells- in my experience.


Th hacker/feigao s can is VERY similar to the lehner basic xl in terms of size/power etc.. The 8s is somewhere between the xl4200 and xl5000. I wouldn't recommend a hacker/feigao for a tc3 unless you plan to secure the endbell mechanically(and I am a dealer for Feigao). I drill/tap the endbell and put small screws to secure the bell on my motors. In my tc3, I run a 4200 with 11.1 volt li-po cells. I find the 4200 slow on 6 cells, but it FLIES on 11.1 volts! The ball diff problem you had is most likely due to poor/improper adjustment. I have yet to have diff isues on 11.1 volts. The xl5000 is probably an excellent choice on six cells, or the basic 5300. I know the 5300 on 7 cells is pretty fast. The Hacker c40 series motors work well, too(fixed endbells vs the b series).

[johnrobholmes]

why do you suggest fixing the enbell on the motors? is this with the stock tc3 motor mount? are you recommending this on all feigao motors? or do you just mean that the torque is crazy and will spin the can in the stock tc3 mount. if i had looked over the specs on the hacker style motor i would have realized the power similarities! thanks for the heads up. i wouldnt doubt my balls diffs were completely my fault. i got it used, and they could have been trashed before me too. good to hear that its not the diffs, its me!

[mac0326]

why do you suggest fixing the enbell on the motors? is this with the stock tc3 motor mount? are you recommending this on all feigao motors? or do you just mean that the torque is crazy and will spin the can in the stock tc3 mount. if i had looked over the specs on the hacker style motor i would have realized the power similarities! thanks for the heads up. i wouldnt doubt my balls diffs were completely my fault. i got it used, and they could have been trashed before me too. good to hear that its not the diffs, its me!

The endbells are pressed into the can. Compression and glue of some sort is the only thing holding it in. The tc3 motor mounts facing the rear, making it especially susceptible to popping the can. If the car hits something and stops suddenly, the motor will come apart. I would recommend this on any Feigao or hacker "b" motor that works in a harsh environment, or is likely to sustain an impact at some point. I've seen some kind of brace made for this purpose(Starluck carries it I think), but it seems bulky to me, and that's why I use screws.

[havy]

The endbells are pressed into the can. Compression and glue of some sort is the only thing holding it in.....
I've seen some kind of brace made for this purpose(Starluck carries it I think), but it seems bulky to me, andthat's why I use screws.


can you show pics?

havy

[mac0326]

If I knew how to post a picture, I would. I can e-mail a picture, if someon want to post it.

[FninjaP90]

When you post, go to

Additional options, Manage attachments, and upload your picture from your hard drive. Easy as that.

[Andrewg]

re the motor sliding forward on impact - a thrust bearing on the output shaft would also prevent that occurring and is a simple fix.

It would fit between the spur and motor can - and the clearance has to be less than the shaft endplay- it can be shimmed and is a slip on fit.

[mac0326]

The file is too large. That thrust bearing sounds interesting. I'd like to see a picture of that. I will try to make a smaller file and upload the setscrew picture.

[DualBL]

mac0326's 9L motor.
-Nick

[johnrobholmes]

ohh, cool. looks easy enough for a steady hand and a center punch to get started. why dont they make the cans removable? i would love to be able to rewire the motor and have a "new" brushless sometimes.

[Andrewg]

Apologies guys the thrust bearing idea wont work I was thinking back to front - how about a bracket in the trya of the car?

A brushless cant be reqound like a 05 motor; unless you have some very expensive machinery. The windings are inside the can not on the rotor. Only Lehner sells spare rotors as far as I know. So you could switch cans.

[starluckrc]

Can popping usually happens form the rear. Disassembling motors will void the warranty making the brace a better idea if it will fit from my standpoint. I have done
the set scew method as well. Not much material to work with.

[havy]

I take it you would have to disassemble the motor to do the set screw right? I'm thiking you would have to remove the debree from the initial hole drilled. So are there any pics of the motor brace?

ohh, thanks for the pic, very interesting mod... and although I think the motors are much more reliable than any other I've tried, I guess I would like to keep the warrenty as they are a bit more expensive. (BL vs. DC)

havy

[DualBL]

http://starluckrc.com/catalog/product_info.php?products_id=67&osCsid=5aa49b5178fab3753888b84077887031
-Nick

[mac0326]

Can popping usually happens form the rear. Disassembling motors will void the warranty making the brace a better idea if it will fit from my standpoint. I have done
the set scew method as well. Not much material to work with.

I've personally never seen a can pop from the rear. I have popped quite a few from the front, though. Your right, there isn't much material. There is more material on the Feigaos than on the hackers, though. It's pretty easy to do, if you pay attention.

[johnrobholmes]

i was under the impression that there was a sleeve inside the can that the wire was wound on and that was it is removable. i was also under the impression that brushless motors are hand wound since the sleeve and wind are complicated- thus the high cost of manufacturing.

[havy]

thanks Nick

havy

[starluckrc]

You don't want to mess with the enamel coated windings. The compressed winds of the Hackers and Feigaos and others were never meant to be removed and are epoxied into place.

[itedinrcz]

In my tc3, I run a 4200 with 11.1 volt li-po cells. I find the 4200 slow on 6 cells, but it FLIES on 11.1 volts!
What is the capacity of your Li-Poly? Does it drain up to 5C/6C??? What if we use 9 subC 3300's (10.8V), should we expect similar results? I have a TC3-RTR, and quickly got bored with it's stock motor and 6 cells. So I've acquired a 7018 (also have a Phoenix 80), Lehner 4200, and I'm looking to push it to a 'safe' high speed limit.

[mac0326]

What is the capacity of your Li-Poly? Does it drain up to 5C/6C??? What if we use 9 subC 3300's (10.8V), should we expect similar results? I have a TC3-RTR, and quickly got bored with it's stock motor and 6 cells. So I've acquired a 7018 (also have a Phoenix 80), Lehner 4200, and I'm looking to push it to a 'safe' high speed limit.


My Lipos are 2000 mah cells that discharge at 15c continuous. I parallel two packs for 4000mah and 60 amp draw(doesn't draw near that much). The two packs together weighs about as much as 5.5 sub c cells. I usually stop driving at the 12-15 minute mark, but have never even close to dumped the packs. I don't want to drain them down too far and ruin them(overdischarging lipos is a costly error). The 9 sub c batts would provide similar speed, in theory, but you would be carying around an extra half pound or so(car would still be blistering fast, I'm sure).

[OptimaMan]

Yeah, the coils are wound on an iron core that is usually epoxied in the aluminum can. I had one motor where the epoxy broke and the whole thing slid out - but the windings were very different from DC motors. They were also "compressed". So, yeah, you would probably need some fancy equipment to rewind bl motors.