How It Works: Electrical system

But if you add a starter, lights, radio, or fuel pumps—needed for low-wing aircraft designs—then you’ll require an electrical system to power them. Usually a battery and an engine-driven generator or alternator combine to perform this task. The battery provides power to start the engine, which then turns the alternator or generator, so that it produces power for the aircraft’s electrical needs (and to recharge the battery). An electrical bus—think of it as a circuit—distributes the power.

Yes, a few other components are required to make everything work. A master switch, which usually has two halves—one controlling the battery, and another for the alternator or generator—enables the flow of power to aircraft systems. (It also allows the battery or alternator/generator to be turned off, helpful if electrical-system troubleshooting is required.) A voltage regulator maintains a constant system voltage, and an ammeter or loadmeter confirms the health of the system; it also indicates whether the battery is charging normally. Finally, a system of switches, fuses, and circuit breakers allow various components to be turned on and off, and protect them from excess current. In many aircraft electrical switches also incorporate circuit breakers.