ESC and powerful motors

[julesbristol]

What would happen if i used a fast motor (15 turn) in my TT01 kit with a standard Electronic Speed Controller? Would a manual SC make a difference?

[Petrolhead]

your standard speed controller would last about half a second with a 15 turn motor. I think the only non-standard motors they can takeare tamiya sport tuned one. I don't think that a mechanical speed controller would last with a 15 turn motor either.

[Ridgeback Racing Team]

Haha no I think with a msc you would see the battery connectors melting or the resistance smoking like a small volcano... Better get yourself a proper esc! also with an msc and 15 turns motor, except for the melting and stuff, you would get a really short driving time.

[mr_pushrod]

A Tamiya kit ESC can safely take a sports tuned, anything less is risky. An MSC on the other hand can take a 19 but you'd have to be on full throttle virtually all the time or the resistor will melt.

[tt-01owner]

a msc can handle any motor thats what everyone used before esc's. as for esc's all esc's can handle all 540 motors. its becuase the ratings are all UNDERRATED. COOLING IS KEY for all esc, a no limit esc can get fried if you overheat it.

[theshopkeeper]

quote:Originally posted by tt-01owner

a msc can handle any motor thats what everyone used before esc's. as for esc's all esc's can handle all 540 motors. its becuase the ratings are all UNDERRATED. COOLING IS KEY for all esc, a no limit esc can get fried if you overheat it.

---

id="quote">id="quote">

I've not read such a load of nonsense in a long time.

Go try an 11 turn motor on a 23 turn esc. It will either cut out, catch fire or both. If it doesn't you're very, very lucky - and you've found the 1 in maybe 50 which is vastly overspecd in the batch...

[Jimmy_GT-R]

Also try running a racing stock P2K2 or GM3 Pro with a MSC and see how hot the resister gets, the battery connectors almost fuse together. As said above some ESC's can handle slightly lower wind motors than rated, some people run 23 turn motors with the tamiya Kit ESC fine, others can't. Always go by the manaufacturers ratings, they play safe, but its better than frying an ESC with a hot motor and having no come back.

thanks

James

[tt-01owner]

ive ran a 11 turn motor with my xL-1 (20 turn ratting) and it doesnt overheat, i ve done this for 3 mounths now.just check the esc amp rating not turn rating.

[mr_pushrod]

Is this a Traxxas XL-1 ESC? They melt when running motors far milder than that! I've seen quite a few as well considering the LHS I work in sells Traxxas cars.....

[tt-01owner]

you know most esc ratings are 70+amps and a 6 turn motor is like 28amps. bassed on the motor puts out 200 watts and 7.2volts. also my friend ran a tekin rebel with a 150amp rating in his boat with 400amps going through his esc for half an hour the esc had no damage!

[mr_pushrod]

A motor pulls way more than 28 amps under load while the lower the turn of motor, the higher the current draw. ESC ratings need to be followed unless you want a smoke machine attached to your car. Also, what motors was he running to have a constant current draw of 400amps and what batteries did he use for that?

[theshopkeeper]

Also, a road car with poor grip will pull much lower current moving off from rest on full throttle (the wheels will spin) than an off roader on grass with grippy tyres or even the same road car on carpet with carpet tyres.

There is a point here though: Turns is a appalling way to specify speed controllers. Almost all ESCs have a peak and steady current draw rating. Motors should specify the same, although very few do as turns is only one factor in the performance rating.

I'm sure that a cheap sub £15 11x2 would draw far more current and run slower than one costing three or four times the amount, yet on rule of thumb they must be "the same" as the only rating is a number telling you how many times the wire is wrapped round the core of the motor - nothing tells you how thick the wire is, it's resistive value, the power of the magnets or the quality of the bearings (or even the brush angle) which will all make a difference to the current drawn.

[DJTheo]

quote:Originally posted by tt-01owner

a msc can handle any motor thats what everyone used before esc's. as for esc's all esc's can handle all 540 motors. its becuase the ratings are all UNDERRATED. COOLING IS KEY for all esc, a no limit esc can get fried if you overheat it.

---

id="quote">id="quote">

Please stop writing this nonsense in every topic, as you may lead newbies into trouble! If you got lucky till now, happy for you, but you can't generalise. Companies aren't dum, stating their ESCs can't handle hot motors, of course they would write if they could, or rebadge cheap entry ESCs into expensive no-limit ones [] Also what do you mean with motors before ESCs? ESCs existed already in the late 70s.

quote:you know most esc ratings are 70+amps and a 6 turn motor is like 28amps. bassed on the motor puts out 200 watts and 7.2volts. also my friend ran a tekin rebel with a 150amp rating in his boat with 400amps going through his esc for half an hour the esc had no damage!

id="quote">id="quote">

A 6 turn motor can take at start more then 100amps, Watt rating is at best efficiency. If 400amps were going for half an hour through is ESC he must have had at least an 200.000mAh battery, would like to see that []

[tt-01owner]

ok i will stop. my suscess might be due to good driveterrain design in my elec tc3, thus making less stress on the electronics. also my 20amp discharge rate battery might be a reason for not overheating. but i can guarante this:

you can safely use a 9 turn motor with a futaba mc330 knock off esc, ive been using it for a long time, it never overheats.

[Jimmy_GT-R]

Battery dischanrge rate doesn't make enough difference for a motor or ESC to overheat. If a motor is pulling enough amps from the battery and through the ESC, I really can't see how a good 20amp discharge rate would make any difference, especially as use say yyou use sanyo 3000 cells, which are nimh cells which in theory don't need discharged as much as nicads. Discharging nimh cells won't have much outcome on the heat of the ESC especially when you still a low turn mod motor in the car with a cheap ESC, unless its massivly geared high, in the 12's, 12.35 etc. The TC3 is an old design now, bit like the TB01, so drivetrain eficiency has come along way since then. But you really must have one great ESC, as stated before the special 1 in 50.

Thanks

James

[raemin]

To get back to the subject, they are a few ways to use a slightly bigger motor on a ESC:

Use ballbearings (sounds obvious but should be reminded)

Use 2wd instead of 4wd / or surface with less grip

On road rather than off road

Use smaller pinion

Use older motor... (a 1992 9turn trinity monster horse power will draw much less current than a brand new 12turn)

Use softer springs on the engine

Use cut brushes

Use a well known brand ESC (as their tolerance is higher).

Adjust torque control on your ESC

With some of the above you may use an engine that is one or two turns lower than the recomended factory settings withtout to many troubles. No guarantee though. A last thing to consider is that an ESC that gets hotter is less efficient and deliver far less punch. Maybe that the standard ESC would be Ok with a 27turn stock engine and a small pinion. I would personnally not push the limit further than that

A very good article about budget ESC can be found here:

http://www.schumacher.clara.net/budgetesc.htm

[El Mexican]

quote:but i can guarante this:

you can safely use a 9 turn motor with a futaba mc330 knock off esc, ive been using it for a long time, it never overheats.

---

id="quote">id="quote">

A disagree, TT-01 owner.

I used a 9 turn Hudy motor in a Futaba 330 and everything got really hot after maybe 3 minutes of use. I plugged in a Dynastorm with a 22t pinion and mainly just drove up and down the street. The problems where evident: the motor used so much current that the receiver didnt function properly, handling was erratic and the bullet connectors, heatsinks, and batteries got stupidly hot.

Of, so maybe I wasnt using the most efficent connectors and the proper car (although most here WILL agree that the Dyna has arguably the most efficient transmision of all Tamiya buggies) but I can honestly say that Futaba MC330 will NOT be able to handle a 9 turn motor under MOST--no all- conditions.

[tt-01owner]

i check the brushes after runing it everytime and its not purple which means its not overheating and the heat sink isnt hot when i run it. and that esc is very tuff i accidently shorted out the esc for 10 minutes before, it melted the case, but it still worked. thus the heat from running the car will only do normal wear damage.

this is just based on my experience.

ps i run a yokomo rev tech 9 turn motor

[DJTheo]

What does a battery discharger have to do with the current a motor draws? Except if you mean a current limiter on the ESC, like hi-end ESCs have, but I don't think the mc330?

Cheers

[tt-01owner]

i didnt talk about battery dischargers, i was saying that the battery discharge rate has to do with cooling. like most batterys have 30amps discharge rate, but sanyo's have a 20amp rate which is better for cooling.

[mr_pushrod]

The battery doesn't control how many amps get used, it depends on what motor you use and how much you use the throttle!

[theshopkeeper]

This is upside down anyway - if the battery is rated for a 30amp discharge rate then drawing at 20amps would keep it cool, if it s a 20amp rated pack then trying to draw at 20amps would make it warm, trying to draw at 30amps would make it very hot indeed.

[DJTheo]

As mr pushrod said batteries don't have discharge rates as current is mainly consumer and not source dependend, what you probably mistook is that manufacturers state/measure their capacity at some standard discharge rates, but that doesn't limit the battery to 20amps, only some ESCs with current limiters can do that.

Cheers

[raemin]

It might be slightly off-topic but for any information regarding battery, motor and ESC, I would highly recomend you to have a look at team orion website Oscar JANSEN motor FAQ. There are a few good tips regarding consumption management and cooling.

Finally if you want to get precise information on motor amp draw, power and efficiency, just search on the web for an excel sheet that was used for tekin dynos. These excel sheets allow you to deduct mathematically the motor figures (power amp efficiency) at various RPMs based on the manufacturer figures.

What one should bear in mind is that ESC are rated so has to operate on average at motor best efficiency, and accept peak and draw equivalent to the motor maximum power. In other word a 17turn ESC should accept a continuous amp draw equivalent to the amp draw of a 17turn engine at best efficiency (i.e approx 50 amps), and a peak peak power that is roughly twice as much.

Based on the above mentioned tekin formulas it is true that one can theoretically attach a 12turn engine to a 17turn ESC if the motor is totally undergeared (just have to find at which revs the engine consumes 50amps...) , the disadvantage is that under such circumstances the motor is reving miles away from its best efficiency and peak power. The result is a total waste of power: If the ESC is rated for 50 amps when attached to a proper 17turn engine that's rated 75% efficiency, 37.5amps will be converted into power, 12.5amps will be disipated. On the contrary, if the engine is a 12 turn, and assuming it is properly (?!?!?) undergeared, at 50amps this engine will deliver 50% efficiency (instead of 70% at 80amps), hence it will dissipate 25amps. We end up with a combination that is 30% less powerfull, and this is assuming that the engine has been properly undergeared, if this was not done, then the device that will dissipate power is not the engine but the ESC, which will lead to:

-ESC will heat => resistance will increase => ESC will heat more ...

-even more loss of power.

-ultimately destruction of the ESC

I'll try to send my own custom excel sheet and a few pics if I find the time to illustrate this issue.

[DJTheo]

If the motor doesn't work as its best efficiency, it is the one dissipating energy and heating up, not the ESC. Generally, revving a electric motor high is no problem as current is opposite proportional to RPM, only the produced power is low, but as said since the current and power is low, so the wasted energy is also low.

Cheers