“Regenerative braking” is a term you normally hear when people talk about electric cars. The other terms, of course, are “range” and “charging times”.
But for this story, we’ll cover what regenerative braking is. We’ll also discuss why electric vehicles (EVs) still need mechanical brakes.
WHAT IS REGENERATIVE BRAKING?
This means that when you brake in an electric car, the energy otherwise lost through braking (friction) is recaptured and stored in the battery. Hence the term “regenerative”.
When a motor is supplied with electric power, its shaft spins and transfers this power to the driven wheels.
However, when you release the accelerator pedal, electric energy stops flowing to the motor. As the car decelerates, the process is reversed.
The wheels turn the shaft, which in turn drives the motor. The motor, in this state, becomes an electricity generator.
And since power is not flowing to the motor and driving the wheels, the electric car will slow down and eventually stop.
IF THIS IS TRUE, WHY DOES AN EV STILL NEED MECHANICAL BRAKES?
Regenerative braking can slow down and stop an EV. But it does not do this as quickly as conventional brakes, especially if you are travelling at higher speeds.
You will need a longer braking distance if you rely solely on regenerative braking.
When you need to stop quickly, mechanical brakes are better than regenerative brakes. When you’re in bumper-to-bumper traffic, you need conventional brakes because the distances between vehicles are so short.
IS IT TRUE EVs COME TO A COMPLETE STOP WHEN USING REGENERATIVE BRAKING?
Yes, they do. And they don’t move again until you apply power.
But for added safety, you should always keep the brake pedal depressed, even when the car has stopped.
However, if you came to a halt using the conventional brakes, the EV will still creep forward when you release the pedal. This is because regenerative braking was not engaged.
CAN THE “CREEPING” FUNCTION BE DISABLED?
Yes, certain models, such as the Jaguar I-Pace, let the driver disable the creeping function. However, this makes low-speed manoeuvring trickier.
Imagine you’re parking your EV and have disabled the “creep” function. Every time you release the accelerator, the car comes to a complete stop.
It’s much easier if the EV is still creeping forwards and backwards.