The Main Circuits of the Automotive electrical system: The electrical system of an automobile consists of four main circuits and a number of branch circuits. The four main circuits are the charging circuit (generating circuit), starting circuit, ignition circuit and the lighting circuit. There are two sources for the generation of electricity (electric current) in automobiles i.e. battery and generator. All the main circuits are connected together and linked to a car battery. There is a considerable variation in the use of electrical symbols between different vehicle motor vehicle manufacturers.