What Is EV Regenerative Braking & How Does It Work?
Traditional internal combustion engine (ICE) vehicles use mechanical brakes for stopping power. When you step on the brake pedal, the hydraulic system causes the brake pads to press against the brake discs. The friction between their surfaces causes the wheels to slow down and the rate at which this happens determines how quickly said vehicle comes to a stop.
In an electric vehicle, things happen a little differently. Though they have a similar braking setup as their ICE counterparts, it’s assisted by regenerative braking. When you step on the accelerator pedal, the electric motor is supplied with power from the battery pack. This creates rotating magnetic fields that cause the motor’s rotor to turn, which then turns the wheels.
When you step on the brake pedal and depending on how quickly you’d like to stop, the electric motor works with mechanical brakes to bring the vehicle’s speed under control. In this situation, the motor works in reverse to its regular mode of operation.
Instead of being supplied with power to move, the rotation of the wheels causes the motor’s rotor to keep turning. This movement induces an electric current in the circuit, which is then used to charge the batteries. A good deal of energy is needed to turn the rotor due to the resistance it offers, and this is what slows the vehicle down.
This way, the motor functions as a generator, producing electricity instead of consuming it. Here the momentum of the rotating wheels is converted into electricity. It’s a clever way of reclaiming energy that would have been lost due to heat and friction with mechanical brakes.
Hence why its termed regenerative braking. Depending on the speed of the vehicle and effectiveness of the braking system, the energy that’s recovered while braking can vary. Some electric vehicles require one pedal driving, which means you only modulate the use of the accelerator pedal to accelerate or decelerate.
However, it can be turned off to allow you to coast when cruising instead of having regenerative braking slowing you down. But for instances where the braking force required exceeds the capability of the motor, the hydraulic brakes step in to apply the necessary braking force.
Regenerative braking works well in medium speed, city traffic as well as when going down hills. In these situations, there’s no immediate need to come to a stop, there’s sufficient momentum and only a low amount of force is needed to keep the speed in check.
How well you modulate your braking needs will determine the amount electricity that can be “regenerated” to charge the batteries. In certain instances, the system can recover about 70% of energy that would otherwise be lost due to heat and friction if traditional hydraulic braking were used.
