How bumps and bad asphalt can charge your electric car

An electric car hardly uses its physical brakes. As a rule, it brakes via its electric motor and thus recovers part of the kinetic energy. But what if you could also generate electricity via the wheel suspension…

The wheels of a car drive up and down through poor asphalt, potholes and speed bumps, among other things. BMW has now discovered that it can also be used to recover energy.

Energy recovery through the suspension

Bumps in the road are absorbed by a car’s springs and dampers. The energy released in the process actually dissipates, mainly as heat. But that has to change, says BMW.

The southern German manufacturer has patented a very clever idea, as the website CarBuzz has seen. Simply put, BMW added an arm to the suspension that moves up as the wheel compresses and down as the wheel extends.

The arm is attached to a generator with a flywheel and a small clutch. When the wheel is compressed, the arm moves the flywheel, but the clutch is open. So the generator is not running.

As the wheel extends, the clutch closes and the energy stored in the suspension is transferred through the arm and flywheel to the generator, which produces electricity.

Why only on the outbound hub?

Why does it only work on the away stroke? Because a wheel suddenly collapses when it hits a pothole. The suspension must then transfer as much energy as possible to the suspension as quickly as possible. The rash is slower and more controlled.

Electricity you recover is free

The benefit of the system is that the energy you recover from the suspension is virtually free. You’ve already used up the energy to go, you get some of it back through the brakes, so whatever comes through the suspension is extra.