Question for Patrick

[lutach]

Hi Patrick,

I have a Recoil and I went to test it out today with the Mamba Max and it ran hot. The motor I'm using is the Mega ACn16/15/1 (9200Kv) and the gearing is 16T/58T. Now the funny thing is that I was using a 60A ESC and it was working really good until I changed the timing setting and I burned some FETs. The 60A ran about 4-5 hours and never got as hot as the Mamba Max did today. I have the newest firmware and all, but what is the appropriate timing you recommend for a 6 pole motor. Most other companies recommend 15-30 degrees of timing, 15 being for optimum performance and 30 for maximum power.

Regards.

[myndseye]

9200kv??? What is the rpm limit of the Max with a six pole? I know that a four pole is double the processing so the limit is halved, but what would that six pole'r do to the equation?

[lutach]

Originally Posted by myndseye

9200kv??? What is the rpm limit of the Max with a six pole? I know that a four pole is double the processing so the limit is halved, but what would that six pole'r do to the equation?

I know a few controllers that can go up to 240,000rpm for 2 pole, 120,000 for 4 pole, 80,000 for 6 pole and 40,000 for 12 poles. I will wait to see what Patrick will say though as I'm not an engineer.

[Arct1k]

Fair point this would be the equivalent of a 27000kv feigao... What voltage were you using?

[lutach]

Originally Posted by Arct1k

Fair point this would be the equivalent of a 27000kv feigao... What voltage were you using?

I'm only using 2S Thunder Power 2200mAh Extreme V2.

[What's_nitro?]

That is quite a strain for any controller, actually. The MM has to have a 240K limit for 2 polers otherwise you couldn't use this setup.

7.4*9200=68080, and being a 6 pole motor- 68080*3=204240. It's like running 204K rpm with a 2 pole motor! That will stress ANY controller.

Yeah I've heard the same about the 15-30* timing. What setting are you on now? Have you tried it at a lower setting?

[lutach]

Originally Posted by What's_nitro?

That is quite a strain for any controller, actually. The MM has to have a 240K limit for 2 polers otherwise you couldn't use this setup.

7.4*9200=68080, and being a 6 pole motor- 68080*3=204240.

It's like running 204K rpm with a 2 pole motor! That will stress ANY controller.

Didn't strain the 60A I had in there before. That controller burned the FETs due to me not paying attention to the program box. I set the wrong timing instead of something else. The MM is actually running it ok, accept it's getting hot and the small 60A controller wasn't. I know people put the MM through worst and I can't seem to understand why it's heating like this in a small car with a small motor that is asking for max 40A.

The timing I have now is normal (10) and I haven't tried any other setting as today was the first day at the track with it. I'm afraid to lower the timing and have similar issues that I had with the other controller.

[What's_nitro?]

It could be the same "problem" people are seeing when the go from the MM to the MMM. Some were complaining that a setup which ran fine on the MM was now getting too hot with the MMM. The FETs in the MM may be much lower resistance than your 60A controller and so allow a much higher pulse current to pass through to the motor. Is the motor getting hot too? If not, I'm kinda stumped... That's all I can come up with right now.

[lutach]

Originally Posted by What's_nitro?

It could be the same "problem" people are seeing when the go from the MM to the MMM. Some were complaining that a setup which ran fine on the MM was now getting too hot with the MMM. The FETs in the MM may be much lower resistance than your 60A controller and so allow a much higher pulse current to pass through to the motor. Is the motor getting hot too? If not, I'm kinda stumped... That's all I can come up with right now.

The 60A uses the same FETs (At least I think it is) as the MM. The motor's temp is normal.

[What's_nitro?]

Yep. I'm stumped. PAATRICKKK!!! Hellllp!

[Pdelcast]

Lutach,

What timing are you running now, when you see the temperature problem?

I'm kind of skeptical that a 6 pole 9200Kv motor will ever work really well -- the commutation frequency is so high that the recirculating currents will never cease -- there will be recirculating currents running through all three phases all the time.

I don't know where the best timing would be for that kind of motor. I'd think you would need to set the timing kind of high, but I'd need to look at it with an oscilloscope to be sure.

Patrick

[lutach]

Originally Posted by Pdelcast

Lutach,

What timing are you running now, when you see the temperature problem?

I'm kind of skeptical that a 6 pole 9200Kv motor will ever work really well -- the commutation frequency is so high that the recirculating currents will never cease -- there will be recirculating currents running through all three phases all the time.

I don't know where the best timing would be for that kind of motor. I'd think you would need to set the timing kind of high, but I'd need to look at it with an oscilloscope to be sure.

Patrick

Patrick,

I have the timing set to normal. Let me know the best timing for this little high RPM motor.

Regards.

[Pdelcast]

Originally Posted by Pdelcast

Lutach,
I don't know where the best timing would be for that kind of motor. I'd think you would need to set the timing kind of high, but I'd need to look at it with an oscilloscope to be sure.
Patrick

QFT

[What's_nitro?]

Is there such a controller which has variable timing, not just incremental? That way you could "tune" your brushless setup.

[Sammus]

I thought I read somewhere thats how sensorless BL esc's worked (castles in particular) - that the timing varies with the RPM. I also read (in the drivers ed guide maybe? cant remember) that the esc detects the optimum value for the timing, and the timing adjustment just varies it within that optimal range. Does this sound right?