Which type of battery is most common in general aviation aircraft, and what is its primary function?

• A. Nickel-cadmium battery; provides starting power and standby source for essential systems.
• B. Lead-acid (or AGM) battery; provides starting power and standby source for essential systems.
• C. Lithium-ion battery; provides starting power and standby source for essential systems.
• D. Alkaline battery; provides starting power and standby source for essential systems.

Answer: (B)

In general aviation, the battery’s main job is to deliver the high current needed to crank the engine for starting and to provide a reliable standby power source for essential systems if the electrical generation isn’t available. Lead-acid batteries, including the sealed AGM type, are the most common because they offer proven reliability, good performance, and cost-effectiveness for providing starting power and backup power to essential avionics and instruments. AGM batteries, in particular, are popular in modern cockpits because they’re maintenance-free, handle vibration well, and are safer in a cockpit environment while still delivering the necessary starting power and standby capability. Other chemistries like nickel-cadmium or lithium-ion appear in some aircraft but are less common for the standard GA fleet due to certification, cost, and safety considerations; alkaline batteries aren’t used as the primary starting/standby power source in general aviation.