Car batteries are fundamental parts of both the charging and starting systems. Within the starting system, the role of the battery is to send a current of electricity to the starter so that the vehicle is able to start and run. In addition, the battery is responsible for supplying electricity to other electrical components, such as the radio and the internal and external lights when the demand exceeds the supply of the alternator or when the vehicle is off. Most vehicles use one battery, but vehicles with diesel engines, electric vehicles, or vehicles that run a 24-volt system may require two or more batteries to power their engines and electric systems. Currently, the SLI battery is a popular type of battery used in many vehicles. The letters, which stand for starting, lighting, and ignition, indicate the battery’s major functions. Overall, an automotive battery is an essential component in vehicles. Without a working battery, an engine will not start. As such, it is important for a driver to keep watch over battery life.