MM Heat Issues

[macr0w]

There are alot of guys successfully using the MM in their conversions. I know people who are running 20 minute mains no problem with the same vehicle, same motor, same esc.

I just can't figure out what you guys are doing to keep your MM's so cool. Or what I'm doing wrong.

I have a Mugen prospec buggy and truggy. The buggy has claimed 1 MM and 2 MMM's. All three went up in flames.

The truggy is new and I put another MM in it.

At no point with the either vehicle have I been able to run more than a few laps without thermal shutdown. I was able to run ok for a bit with my second MMM. One weekend I was able to finish three 5 minute qualifiers and a 10 minute main with no trouble. The next weekend it went up in flames before I even raced during practice.

I've done the case mod, tried 2 fans, tried 1 fan, went to direct solder on the motor, geared the buggy down to 10t/46t and the truggy is 11t/46t. Body is full of holes, now I'm using a receiver pack. Defaulted and recalibrated my radio. (which is a Spektrum DX3.0)

I have a Polyquest 4s 5000mah 25c and a Polyquest 4s 6000mah 20c battery.
The buggy has a Neu 1512/1.5/D/F and the truggy has a Neu 1515/1.5/D/F.

Both vehicles get up to 170 degrees fast and shut down. I have talked alot to Tom Frie about my setup. He has seen my buggy at the track. (in flames)

There is no binding in the drivetrain. They roll freely with the motor disconnected. I have 30k in the center diff on both vehicles.

My installs are clean. I've posted pics on here before. I can't figure out what to do next. I'll never be able to race like this.

Any thoughts?

both of your motors you have listed draw a lot of amps, if you have the cash buy a couple of new motors that have a higher wind, and also check the timing for the ESC if they are not at 0 this will cause heat...running the timing does speed up the motor a little but not worth the heat buildup IMO

also make sure you are using an external BEC with the onboard bec disabled

[macr0w]

Yeah, I keep the timing down to 0 Lowest and the punch has been moved all around from disabled to 90%.

I used the CCBEC on the battery leads of the MM. Of course I pulled the red wire from the lead to the receiver.

After I went to a receiver pack I used it as a voltage regulator. But I took it off because it was glitching the esc.

have you tried gearing up?

[Finnster]

Yeah, those motors are way way too hot of winds. 3300 and 2700kv is asking for trouble. your buggy's motor is pinning over 45k rpms. No way you are going to make 20min either on those batts pulling that many amps.

You have to get a lower kv motor. If you are racing, i would suggest getting a motor that would spin 28K-30K rpms. Even better would be to go up in voltage w/ the MMM and get the motor to match (like a 1515 2.5D on 5S or a 3D on 6S (maybe a 1.5Y on 6s too))

[Arct1k]

I found that the MM needed the extra cap for 4s - Add a novak HV cap 2700uf.

I burned up 3 MM to (one due to motor failure) - Since adding the extra cap no issues.

[macr0w]

Originally Posted by Finnster

Yeah, those motors are way way too hot of winds. 3300 and 2700kv is asking for trouble. your buggy's motor is pinning over 45k rpms. No way you are going to make 20min either on those batts pulling that many amps.

You have to get a lower kv motor. If you are racing, i would suggest getting a motor that would spin 28K-30K rpms. Even better would be to go up in voltage w/ the MMM and get the motor to match (like a 1515 2.5D on 5S or a 3D on 6S (maybe a 1.5Y on 6s too))

I would agree with you if there weren't so many people with the exact same setup who are running good. HappyWing for instance is running the exact same setup I believe.

Originally Posted by Arct1k

I found that the MM needed the extra cap for 4s - Add a novak HV cap 2700uf.

I burned up 3 MM to (one due to motor failure) - Since adding the extra cap no issues.

I thought about trying this. Maybe it's my next step.

[Finnster]

Originally Posted by macr0w

I would agree with you if there weren't so many people with the exact same setup who are running good. HappyWing for instance is running the exact same setup I believe.


I thought about trying this. Maybe it's my next step.

IDK about anyone else, but 3 burnt ESCs between 2 cars, 2 motors and 2 batts says something is seriously wrong with the setup &/or driver.

On the trugg, your FDR is nearly 20:1, that really really low for such a powerful motor like a 1515. Even with that hot motor you should be somewhere like 15:1 as starters. That puts you at 50ish mph and 150A at least. You've tried to gear down for a reasonable track spd, but a motor's efficiency dies if the motor is not properly loaded. Low eff, lots of heat. That may be a big factor. If things are setup right, you won't need all the fans and crap nor a swiss cheese shell. FWIW, RCM Mike runs a 2.5D on 5S, and I had a 2y (1100) on 9s A123 (about 28K rpms too) and both have plenty of power for the track and no crazy thermalling.

Also, the way you drive may be contributing. Do you stab at it like a nitro? How aggressively are you pushing it? That may be something to do with it as well. I hope a cap fixes it, but IMO you have probs beyond what a cap can do.