Internal combustion engine
All the electrical accessories in a car are controlled and powered by an alternator which converts some of the engines mechanical energy into electrical energy. The alternator also charges the internal battery of the car. However the alternator is powered by the timing belt which only moves once the car is started and therefore it cannot be used to start the car and that is why a battery is needed. The alternator works with a timing belt that rests on a pulley attached to the alternator that moves once the car is started. When the timing belt spins the pulley, it turns a rotator shaft attached to the pulley which spins magnets around a coil. The spinning magnets are responsible for creating a current known as alternating current (AC) around the coil and is then directed to the alternators rectifier which changes the AC into another current called direct current (DC). The DC current is used to power the car and its electrical systems.