Your car’s battery stores electrical power needed in starting the engine. When the key is turned to the start position, electricity from the battery goes to the starter. After the engine starts, the alternator takes over the job of supplying the electricity to keep your car’s engine running. The battery is basically a plastic box with metal plates submerged in a mixture of water and acid. Two cables are connected to the battery. The positive cable is connected to the starter and other accessories, and the negative cable is connected directly to your car’s frame. If your car’s is equipped with a maintenance-free battery, there’s no need to add anything to it. If your battery is equipped with vent caps, you may need to periodically check the level of fluid and add water as needed. Contact a mechanic or auto parts store in your area for more information about batteries.