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.
Last reviewed
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.
Why anyone buys a 14500
Torches. A single 14500 gives an LED driver 3.6 V from one AA-sized cell, which is why enthusiast flashlights list it alongside AA and run much brighter on it. Those lights are built to accept both and say so explicitly on the box. That is the only context in which the two belong in the same sentence.
What failure looks like
Best case, a device with a regulator shuts down and survives. Worse, the extra voltage cooks a component and the device dies quietly. Worst, in something with a sealed compartment and no protection, the cell is over-discharged or shorted and vents. Li-ion cells vent hot and hard, and an AA-shaped one is no exception.
Protected and unprotected cells
Some 14500s carry a small protection board in the end cap that cuts off on over-discharge or short; others do not, and are marginally shorter. Unprotected cells belong only in equipment with its own battery management. If you cannot tell which you have, treat it as unprotected.
Can I use an 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.
14500 vs AA: common questions
Is the AA a direct replacement for the 14500?
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.
What is the difference between the 14500 and the 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. In short: same shape, more than double the voltage — never swap them.
Are the 14500 and the AA the same size?
No. The 14500 is 14 × 50 mm and the AA is 14.5 × 50.5 mm.
Which lasts longer, the 14500 or the AA?
The AA. It is rated at 1800–2900 mAh against 700–1000 mAh for the 14500 — roughly 2.8× the capacity, though real runtime depends on how much current your device draws.
Is the 14500 rechargeable?
Yes, and the AA is not. Never put a AA in a charger: single-use cells can vent, leak or catch fire when charged.
Background reading
The wider questions behind these two codes.
Lithium for cold, weight and high drain; alkaline for everything else
NiMH for anything you replace often, alkaline for anything you forget about
Switch anything you replace more than twice a year
Lithium for standby and extremes, NiMH for anything used often