[zeropointbug]

Well said AAngel. :dft009:

Theoretically, the higher the voltage, the better... but like AAngel said, it's more to do with what actual equipment we have that has not been made to up most standards (in my books), in particular the Feigao motors. They are going to run quite hot no matter what you do, basically, the more power you pull from them, the more heat, and sometimes not even that, they are very picky what kind of load they have on them... won't go into that now.

Look at it this way for Feigao's, say you spin an XL motor under load at 30,000rpm, one at 4s and the other at 6s lipo (making the appropriate Kv. rating choice for each voltage). Now, Artur says the Feigao 7XL motor runs at ~70% efficiency under max power, just as an example... now say that the 4s setup will get you ~71% efficiency at max power, then going to a 6s setup(with appropriate Kv. motor to maintain 30Krpm) will get you ~72.5%... you gain 1.5% efficiency (example) when running higher voltage (normally this is a large difference), but since the 'overall' efficiency of the motor tech is poor, the higher voltage setup will not make that much of a difference as far as heat output. IIRC, 1200 watts for XL motors, so the 4s setup will put out 490 watts of heat (max power...how long do you think it can do that for:005: :013: ), and the 6s setup will get you 455 watts output of heat. Mind you, you are not drawing max power all the time, but you get the point.

Now if we look at a Lehner or a Neu motor which normally run ~88% efficient under max load, now impose the last 'Feigao' example to this, the 4s setup might get you 88% efficiency, then the 6s setup might increase this closer to 90%. As you can see, this same 'percent increase' will give you larger payback as far as running temp. But, at the same time, the Lehners and Neu are supposed to run cool at any voltage setup, but simply, the higher voltage, the cooler it will run.

NOTE: These brushless motors also have different efficiency curves at different voltage setups as well... hence real world applications may vary. On the same note, efficiency should NOT be confused with motor running temp, as they don't really go hand in hand. ex. You can have a 90% motor running at 1800 watts, that's 180 watts of waste heat (motor will run hot)... as well you can have a 80% motor and running 800 watts power, and have 160 watts of waste heat (still hot, but a tad cooler), the 90% efficient motor is going to run hotter.

I say run a 4s lipo setup or 5s2p A123 pack and you are set, go for an 8 or 9XL for the low end, or a Lehner or Neu for cool running. If you want to run high voltage, get a Neu or Lehner if you want to maximize benefits.

I am currently switching to a Neu 1512/3D (1700Kv.) running on 7s2p A123 (23.1v/4.6Ah), this is going from a 5s2p and 7XL, I am expecting huge benefits from this change.