Originally Posted by rcguy2477

to expand on the diode part-

A motor acts as a generator when the shaft is spun by an external force. This spinning causes back emf (Definition- Back Emf is an Electromotive force that occurs in Electric motors where there is relative motion between the armature of the motor and the external magnetic field. When the coils of the motor rotate, the magnetic flux threading through the area between the coils is constantly changing. This causes a back Emf that, by Lenz's law, opposes the motion of rotation.) The purpose of the diode is to use up all the voltage emitted from the motor while braking(when the car is spinning the shaft of the motor). Many components are prone to fry when a voltage is applied in reverse of what it is designed, specifically the f.e.t.s located in the esc.