A23 vs A27
Both are 12 V alkaline stacks of nearly identical length. The A23 is 10.3 mm across against 8 mm and holds roughly double the capacity.
Both are 12 volt batteries built from a stack of tiny cells inside one shell, and both turn up in garage remotes and car alarm fobs. They are almost exactly the same length, which is what makes them easy to confuse, but the A23 is noticeably fatter — 10.3 mm across against 8 — and holds roughly twice as much. They do not interchange: an A27 rattles loose in an A23 holder and an A23 will not go into an A27 one. Match the code on the cell you removed.
- Verdict:
- Same 12 V and nearly the same length — the A23 is the fatter, longer-lasting one
- Interchangeable:
- no
Side-by-side specifications
| Specification | A23 | A27 |
|---|---|---|
| Chemistry | Alkaline | Alkaline |
| Type | Alkaline Battery | Alkaline Battery |
| Nominal voltage | 12 V | 12 V |
| Diameter | 10.3 mm | 8 mm |
| Height | 28.5 mm | 28.2 mm |
| Typical capacity | 40–55 mAh | 18–22 mAh |
| Rechargeable | No | No |
| Also sold as | 23A, MN21, V23GA, 8LR932 | 27A, MN27, V27A, L828 |
Size comparison
These cells do not share a footprint, so one will not sit correctly in the other's compartment.
Same length, different width
28.5 mm against 28.2 mm — three tenths of a millimetre apart end to end. Diameter is what separates them, at 10.3 mm against 8 mm, and that is more than enough to stop either fitting the other's clip.
Runtime
40–55 mAh against 18–22 mAh. Both figures are tiny because neither cell is built for endurance — they exist to fire a short radio burst when you press a button, a few times a day for a couple of years.
Why 12 V from something this small
Each is a stack of eight miniature alkaline cells in series inside one wrapper. That buys the voltage a radio transmitter wants from a package that fits in a keyfob, at the cost of almost all the capacity.
Can I use a A27 instead of a A23?
Not directly. The A27 measures 8 × 28.2 mm against 10.3 × 28.5 mm for the A23, so it will not seat properly in the same compartment.
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.