The main problem is battery life – starting a car engine. Also, the battery helps the generator in the power supply of various energy consumers vehicle. After all, on modern cars usually installed a large number of customers current – powered, powerful music systems, a large number of lighting fixtures, etc. When driving in traffic generator is not always itself to cope with supply all consumers. That in such cases to help him and comes battery. Well, the third function battery – powered electroconsumers car with the engine off. But the main thing to remember in time run engine to recharge the battery. After all, if the battery is completely discharged, it will lose some of its power characteristics that will lead to more rapid failure. Yet we should not forget that Battery is an alternative source of energy, resulting in all appliances in working position in case of failure of the generator. In this case, the battery can provide the movement of the car to the nearest service station.