What electric-vehicle system recovers energy while slowing the car?

Regenerative braking is the electric-vehicle system that recovers energy while the car slows.

When the driver lifts off the accelerator or presses the brake, the traction motor can operate as a generator. Instead of sending all the vehicle’s kinetic energy away as heat through friction brakes, the generator converts part of it into electrical energy and sends it back to the battery.

The amount of recovered energy depends on speed, battery state of charge, temperature, road conditions, and the vehicle’s control software. Regeneration is especially useful in stop-and-go traffic, where repeated slowing would otherwise waste energy.

Regenerative braking does not eliminate conventional brakes. Electric cars still use friction brakes for emergency stops, very low speeds, parking, and situations where the battery cannot accept more energy. “Engine braking” is a related driving sensation in combustion cars, but it normally does not recharge a battery.