Co-incidentally we had a tutorial the other night in the Club on ESC's and here, to the best of my recollection, is what was said:
There is really no difference between motors and generators. If you rotate the stator of a motor you will generate a voltage at the terminals.
ESC's work by feeding pulses of power to the motor.
In between the power pulse the motor is still turning and so it generates what is termed a back EMF.
ESC's don't like back EMF's and so are protected by the installation of a suitable size diode at the design stage.
So I guess, having an prop drive the motor would not be a problem and should certainly not damage the ESC. If the back EMF can't get through the ESC it can't reach the battery so allus gud so to speak.
Any more and I've got to see the man that knows
