The kinetic energy of the wheel is generally lost during braking in the form of heat due to friction between the brake pads. This energy can be recovered using a technique called as Regenerative Braking. In this technique, the excess energy is stored temporarily in capacitor banks before it gets converted to heat energy and is wasted. This system prolongs the battery life by recharging the battery using the stored energy. Hence the mileage of the electric vehicle also increases as it can travel more distance in a single battery charge.
In the Regenerative braking system when motor is running at this time stop the motor through AVR ATmega8(Microcontroller) .Due to this action flywheel rotate for some time because of kinetic energy. Therefore few torque produce in flywheel and due to this torque motor is work s a generator. This generated electricity is fed into a chemical storage battery.
Watch on You tube : Regenerative Braking System