3s Mamba pro question
 

I tried running a 3s 5000, speedpassion 3.5 motor with my mmp today and I was havin problems. When I pulled the trigger it would start stop start stop then haul the mail.. This setup is in a drag car.. The only thing I can figure is the amp draw was to much with the 3.5 3s. What do you guys think? I had the esc on smart sense, 4 deg timing med start,( i tried high and low). Without compound on the tires it would jerk once and take off. But with it nothing but stop and go..

Cogging? Do you have the motor wires phased right?

I wouldn't say cogging.. I have a mamba monster that coggs, Id say its more like it shutting of an on.. If I let it spin it runs fine. But a dead hook its like it stalls. I also tried a different sensor wire thinking my new one was defected. This motor is said to be 12100kv.

Are the solder connections solid? LVC too high?

I soldered the wires right to the motor and they are pretty solid. At least I think so lol. And I have no cut off on voltage because I charge every two runs. Its only 132ft at a time.

I'm guessing 12,100 * 12v = 144,000 - i think thats too much for a mmp

Well I have no clue, thats why Im asking the brushless pros ;).. Arct1k, What about a 2s pack? Think that will work better, or should I invest in a different motor?

Since it is "stuttering" at low speed I don't think excessive RPM is the problem. If it were stuttering at the end of a drag run, then that would be the case. Could it be a shorted winding in the motor? Kinda hard to tell, because you don't run long enough to really heat up the motor anyways.

Here's an idea. Drive around for a few minutes at a "normal" pace, maybe 35-40 mph, and see if the motor gets wicked hot. If it does then it probably has a shorted winding.

Ok, I'll give that a try tomorrow or the next day. After the stall it went 88mph but with the start and stop the e.t. sucked.
Is there something I can see that is obvious if there is a shorted wind?

If you can take apart the motor it might be obvious if the shorted wind is on the outside of the coil. If not, then maybe one coil will be a bit darker in color than the others from heating up more...maybe. The windings in a fast motor like that will measure basically zero ohms on any normal voltmeter, so unless you have a VERY accurate meter I don't think you can tell by that method.

The sensors should make your starts way smoother than that at the lower rpms. I wonder if your sensors or the sensor wires are all ok? Since you have it in 'smart sense', it could be automatically reverting to sensorless only. The symptoms you describe sound like the ESC is in sensorless mode only and trying to get rotor position, but is geared rather high, so it's having a hard time at start. Once you hit higher rpms, the ESC goes into sensorless mode, so it would make sense that it runs fine then. Try 'sensored only' (not smart sense). If the motor acts funny all through the rpms now, something is wrong with the sensors/wire.

unplug the sensor and see if the problem improves. If it does, you have a bad sensor in the motor. The same system happened to me before with a 17.5. A new motor fixed the problem.

lol I'm running a MM with a 2.5T on 3cell, i would hope the MMP could take it
(fyi i know thats way over what the motor and esc should be used for thanks)

afew things you could try

-its been said already but remove your sensor wire
-add a bec, you would be surprised how many problems go away when you add a CC BEC.
-try a higher discharge pack ( just a easy test you should always do)
-gear down alittle and try again


the only thing left out is that maybe the motor is accelerating to quickly and its causing a problem with the smart sense mode on the MMP

Jonathan, have the motor wires been soldered in the correct order (A to A, B to B, C to C)? This order must be correct for the sensors to function properly. If you're running without the sensor wire hooked up, the order does not matter in sensorless only mode.

I tried it bout ways.. smart sense and sensored only and the problems are the same.. I'll try a different motor because I've tried two sensor wire, one being brand new and same issue. Thanks for the reply though

I've had the same issue with a brand new duo2 17.5 and I replace the sensor in the motor and it was fine. But it didnt run at all. This thing will haul the mail if it has no traction. Thanks for the reply.

Well the pack is a new thunder power 45c 5000 pack so I would think the discharge is plenty enough... Im out on the bec though.. If it comes down to that, I'll just get another mmm and go back to castle mtrs.. Thanks though

Yes Sunny its all wired proprely.. I run mmp's on the touring cars so I figured I'd try it on my 1.05 car since I already had the equipment. The thing that puzzles me if I line the car up out of the vht and no koford it will run like a raped ape, but med compound and in the groove, nothing. :neutral: