ORIGINAL: Slo-V Flyer
I didn't know WHY or WHAT caused heat in a motor/combo. Add to that, why more voltage caused more heat (without regearing etc etc). Then I found out about the magical Ohm's law and that amp draw increases with voltage, given the same resistance and load, and voila! Now I know why 2s is fine but 3s or 4s cooks motors without proper setup. And now I spread the gospel.
Just remember this is a dynamic situation. You have the ESC varying the duty-cycle (ohm's law is still usable here), and then you have a lot of components ohm's law can't model, induction, back-EMF, etc. Ohm's law and its derivatives work in concept at zero RPM, but once you get that rotor turning, Ohm's law starts to break down.