Start-stop System

It uses a reinforced starter or starter-generator and a stronger battery. Conditions such as cold engine or low battery prevent it from stopping the engine. Mild hybrid systems use a belt starter-generator for quieter restarts and can also recover energy when braking.

The control unit checks battery state, temperature and demand before stopping the engine.

If the system stops working, a weak battery is the most common cause. The system can usually be switched off with a button, but it turns on again at the next start in most cars.