How Does an Alternator Work?

An alternator's main purpose is to maintain the battery. Basically what happens is that it uses the engine power to create electricity and sends it over to the battery to keep it fully charged. Engine power is sent to the alternator via the engine drive belt, aka serpentine belt. This is why it is so important to keep the belt tight and replace it when needed.

When you are driving your car with all the lights on, the windshield wipers on and the radio blasting it uses a lot of electrical power. If all you had was a battery all of this electricity usage would drain the battery in a matter of minutes (sometimes more like an hour depending on how good your battery is). To prevent this from happening and to keep our battery fully charged, we use an alternator.