How do you make electricity from vehicle breaking?

Answer 1

"Regenerative braking", or generating power from the braking motion, is often found in electric and hybrid electric cars. Essentially what is done is to "reverse" the motor leads (usually done by the computer controller) to change the motor into a generator. The generated power is then used to charge the batteries or shunted to ground through a resistor. The load of generating electricity causes the braking effect, not unlike taking your foot off the accelerator in a manual-transmission vehicle.