An AED battery is made for one machine. Pick the make and model from the list at the top of this page and only the batteries that fit will show. Some machines take a battery pack, some take standard lithium cells in a holder, and a few combine the battery and the pads in one pack.

The machine runs its own self-tests and tells you when the battery is low, usually with a warning light or a beep. Replace it when the machine asks, or by the date on the battery, whichever comes first.