Motor braking.

[Serum]

It might depend of motor? Do you think?

That would be determined by the internal resistance (inherent with KV) of the motor.

The motor generates energy once the vehicle is running; some motors KV value are determined by spinning the rotor at X rpm to make 1V. Don't know if this AC is measured over 2 wires or if it's the sum of all three phases.

Basically every electric motor that uses magnets can be used as a generator. It produces energy once it spins. This is the reason why shortening the wires affect the turning resistance of the motor.

You said it yourself; if it spins faster, it has more resistance with the wires shortened.

If you have no batteries attached and you spin the wheels at 60-70mph and the truck is geared for 20mph i am pretty sure the controller will burn.

Perhaps even sooner, but the idea is obvious i guess.

schulze tells the world about the loose contact; he told me that a loose contact is worse on braking than on accelerating; this combined with the fact of his 'store the energy in the batteries' made sense to me.