Hybrid electric cars do not need an external power source to replenish their batteries as they are powered by an internal combustion engine and one or more electric motors that make use of battery energy. The battery can be charged by the internal combustion engine and regenerative braking, as well as other components like the low-voltage auxiliary battery, the electric generator, the electric traction motor, the exhaust system, the gasoline filler, the fuel tank, the spark-ignited internal combustion engine, the thermal system, and the gearbox.
