14500 vs AA
A 14500 is an AA-sized lithium-ion cell at 3.6 V. The AA is alkaline at 1.5 V. They share a footprint and nothing else.
This is the swap that breaks things. A 14500 is the same size and shape as an AA and will drop straight into the compartment, but it is a rechargeable lithium-ion cell running at 3.6 volts against the AA's 1.5. That is well over double what a device built for an AA expects. It can kill the device outright. Nothing about the fit warns you, so read the code on the cell rather than judging by shape.
- Verdict:
- Same shape, more than double the voltage — never swap them
- Interchangeable:
- no
These fit the same space but are not electrically compatible
The 14500 runs at 3.6 V against the AA’s 1.5 V — a 2.1 V difference between two cells that drop into the same compartment. Nothing about the fit stops you making this mistake, so check the code on the cell, not its shape. The AA is also single-use: putting one in a charger built for the 14500 can make it vent, leak or catch fire.
Side-by-side specifications
| Specification | 14500 | AA |
|---|---|---|
| Chemistry | Li-ion | Alkaline |
| Type | Cylindrical | Cylindrical |
| Nominal voltage | 3.6 V | 1.5 V |
| Diameter | 14 mm | 14.5 mm |
| Height | 50 mm | 50.5 mm |
| Typical capacity | 700–1000 mAh | 1800–2900 mAh |
| Rechargeable | Yes | No |
| Also sold as | ICR14500, IMR14500 | LR6, MN1500, AM3, R6 |
Size comparison
Near enough to interchange by hand — 14 × 50 mm against 14.5 × 50.5 mm — which is precisely why the voltage difference matters here.
Why the sizes match
The code is the size: 14 mm across, 50 mm long, against 14.5 × 50.5 mm for an AA. Li-ion cells were numbered to drop into existing tube sizes, which is exactly what makes this pair dangerous.
The voltage gap
3.6 V nominal against 1.5 V, and a freshly charged 14500 sits nearer 4.2 V. A device expecting 1.5 V sees close to three times its design voltage.
Charging
The 14500 needs a lithium-ion charger. An AA is single-use; putting one in a Li-ion charger can make it vent or leak. Neither belongs in the other's charger.
Can I use a AA instead of a 14500?
No — and the fit will not stop you. The AA measures 14.5 × 50.5 mm against 14 × 50 mm, close enough that it will sit in the same compartment. The problem is electrical: 3.6 V against 1.5 V. Fitting the 14500 where the AA belongs feeds a device more than it was built for, which can damage it immediately or shorten its life. Match the code printed on the cell you removed.
Check before you swap. Batteries with similar dimensions are not always interchangeable. Always verify voltage, chemistry and the requirements printed in your device manual before fitting a replacement.