What is the typical system voltage in general aviation aircraft and the common battery type used?

• A. Typically 28 volts DC, with lead-acid or sealed lead-acid batteries (lithium is used on some modern designs)
• B. Typically 28 volts AC, with lead-acid batteries
• C. 12 volts DC with alkaline batteries
• D. 120 volts DC with nickel-cadmium batteries

Answer: (A)

In general aviation, the electrical system is built around a 28-volt direct current distribution. Using 28 volts instead of a lower voltage reduces the current for the same amount of power, which allows thinner wiring and lighter components while still delivering enough power for avionics, lights, and starting. The battery used for starting and as a backup is typically lead-acid or sealed lead-acid, because this chemistry is economical, robust, and well understood in aviation. Lithium-based batteries are starting to appear on some newer designs to save weight, but lead-acid variants remain the standard on most GA aircraft. The other choices describe incorrect combinations of current type, voltage, or battery chemistry for typical general aviation systems, so they don’t match common practice.