Regenerative braking and the brakes on hybrids and EVs

On an electric or hybrid car, the conventional brakes no longer do most of the work. That is good news for the pads, but it brings a problem many drivers don’t know about: brakes that are rarely used fail in a different way.

How regenerative braking works

When you lift off the accelerator or press the brake gently, the electric motor becomes a generator. It slows the car and sends the energy back into the battery through the inverter. The disc brakes only come in when more is needed, for example in a hard stop or at very low speed.

Many EVs also have a “one-pedal” mode, where the car slows firmly just from lifting off. On some models you can adjust it with paddles or in the menu.

The benefits

• You recover energy, so you use less, especially in town.
• Pads and discs wear much more slowly.
• Less brake dust in the air.

The problem: brakes that sit idle

Because they are rarely used and get little heat, the discs, especially the rear ones, collect rust. Calipers and slide pins can seize, and pads can stick to the disc or wear unevenly. At their first roadworthiness tests, some low-mileage EVs fail precisely because of rusty brakes rather than worn ones.

What we check on the brakes

• The condition of the discs on both faces, including the inner face, where rust is not visible with the wheel on.
• Caliper slide pins: we clean and grease them so they don’t seize.
• Brake fluid, which absorbs moisture over time. Most manufacturers recommend changing it about every 2 years; check the interval in your manual.
• The electric parking brake and the system that blends braking between the motor and the discs.

All of these checks are part of hybrid and EV servicing. More on maintenance in our maintenance guide.