Definition
A rating of a battery's ability to deliver electrical current over time, expressed as the product of current in amperes and the number of hours that current can be sustained before the battery is discharged. A 35 ampere-hour battery, for example, can theoretically deliver 35 amperes for one hour, 7 amperes for five hours, or 1 ampere for 35 hours.
Plain English
A measurement of how much electricity a battery can store, shown as how many amps it can supply and for how long before it goes flat.
Context Anchor
Seen in aircraft battery specifications, maintenance records, and discussions of how long electrical equipment can be powered if normal charging is lost.
Derivation
Combines 'ampere' (the unit of electric current, named after French physicist André-Marie Ampère) with 'hour.' Multiplying current by time gives a measure of total electrical capacity, similar to how distance equals speed times time.
Why Pilots Care
Ensures the battery can power essential electrical systems and start the engine reliably.
Analogy
Think of it like the size of a fuel tank for electricity. A bigger tank lets you run electrical equipment longer, just as a bigger fuel tank lets the engine run longer.
Intuition Check
Ampere-hour capacity is not the same as voltage. Voltage is the electrical pressure; ampere-hour capacity is the amount of electrical supply available over time.
Example Sentence 1
The aircraft's 35 ampere-hour battery should run the essential bus for about 30 minutes after an alternator failure.
Example Sentence 2
Before approving the aircraft for flight, the mechanic verified that the replacement battery met the required ampere-hour capacity.