Abstract: A vehicle having an internal combustion engine that drives a generator and a cranking motor that cranks the engine is provided with a standard electrical system as well as a supplemental electrical system. This supplemental electrical system includes a capacitor that is charged by the primary electrical system of the vehicle and is protected against excessive discharge. When it is desired to start the engine, the capacitor is connected to the cranking motor to supply adequate cranking power to the cranking motor, regardless of the state of charge of the batteries.