Definition
An electrochemical device that stores electrical energy in chemical form and releases it as direct current (DC) when connected to a circuit. In aircraft, the battery supplies electrical power for engine starting, provides backup power if the generator or alternator fails, and stabilizes the electrical system by absorbing voltage spikes. Aircraft batteries are typically lead-acid or nickel-cadmium (Ni-Cd) types and are rated by voltage (commonly 12 or 24 volts) and capacity in ampere-hours.
Plain English
A rechargeable power source that stores electricity for the aircraft. It starts the engine, runs the electrical system on the ground before the engine is running, and serves as a backup if the generator or alternator quits in flight.
Context Anchor
Seen during preflight checks, engine start, electrical system discussions, and emergency procedures involving loss of electrical power.
Derivation
From the French 'batterie,' originally meaning a group of artillery pieces fired together. Benjamin Franklin borrowed the term in the 1700s to describe a group of linked electrical storage cells, because they 'fired' electricity together. That's why a battery is technically a set of cells, not a single one.
Why Pilots Care
A failed battery prevents engine start and removes backup power for radios, lights, and instruments if the alternator stops working.
Intuition Check
Do not think of battery only as a small household item like an AA cell. In an aircraft, the battery is the stored electrical power source for the airplane’s electrical system, usually rechargeable and limited in how long it can supply power by itself.
Example Sentence 1
Before turning the master switch on, the pilot confirmed the battery had enough charge to start the engine.
Example Sentence 2
With the alternator offline the battery supplied power to the essential bus until the pilot landed.