How to determine cell count?
 

I have a chance to buy a new never used motor from a friend but he does not know the maxximun cell count,is their a formular to determine this? The motor is a Basic XL4200. Thanks

You generally want to keep the max motor rpm at around 35,000 rpm. So 35,000/4200=8.33v, which is 6 or 7 NiMH cells or 2s lipo.

This is a sort of newb question, but it seems that Novak with their HV max line has completely disregarded this formula. For instance, their 4400kv motor with 14.4 volts = 63,360 rpms. Is this why their motors run so darn hot because in fact they are really not appropriate for an e-maxx application? Their new 4.5 is even a higher KV rating than the 6.5. Why would they make such high kv motors for a heavy rc application? Would it have to do with the system being sensored?

Thanks,
Chris

Well, they might be getting hot because they are spinning kinda fast if that is their true kv rating. That's what happens with sensorless BL motors too; spin 'em too fast and they heat up. Plus, efficiency starts to fall, so more power is being wasted.

The fact it's sensored simply means there is a Hall-Effect sensor to monitor rotor position. Otherwise, it's like a sensorless motor.

I've never had a sensored setup, so I don't know what their "sweet spot" is.

Just FYI, the Novak motors were rated without a load. This causes the kv to drop by 1000 or more. Perhaps that is the reason why they rate their motors in turns instead of kv.