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9V vs AA
9V and AA are not interchangeable. They differ in voltage (9 V vs 1.5 V). The AA holds about 4.9× the energy of the 9V (2,700 mAh vs 550 mAh).
| 9V | AA | |
|---|---|---|
| Type | alkaline cylindrical battery | alkaline cylindrical battery |
| Voltage | 9 V | 1.5 V |
| Size | 48.5 mm × 26.5 mm × 17.5 mm | 14.5 mm × 50.5 mm |
| Typical capacity | ≈ 550 mAh | ≈ 2,700 mAh |
| Rechargeable | no | no |
| Other codes | 6LR61, MN1604, 1604A, 522 | LR6, MN1500, 15A, E91 |
Can I use AA instead of 9V?
No. Different shape: 14.5 mm × 50.5 mm vs 48.5 mm × 26.5 mm × 17.5 mm.
Can I use 9V instead of AA?
No. Different shape: 48.5 mm × 26.5 mm × 17.5 mm vs 14.5 mm × 50.5 mm.
Where each one is used
9V: smoke alarms (battery-only and as hardwired backup); guitar pedals and active pickups; wireless microphones; multimeters and test meters.
AA: TV and streaming remotes; Xbox and other wireless game controllers; carbon monoxide detectors and some smoke alarms; wireless mice and keyboards.
Both sizes turn up in smoke detectors, carbon monoxide detectors, depending on the model, which is why people mix them up: check the code on the old cell.