A petrol car battery is a vital component that provides electrical power to start the engine and run various electronic systems. Typically 12 volts, it stores energy in chemical form, converting it to electricity when needed. The battery powers the starter motor, ignites the fuel, and operates the vehicle's lights, radio, and other accessories. It also recharges while the engine is running, ensuring a reliable power supply for repeated use. Proper maintenance is essential to extend its lifespan.