16340 vs CR123A
The 16340 is a 3.6 V rechargeable lithium-ion cell in the CR123A's footprint. The CR123A is a 3 V single-use lithium cell.
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The 16340 is the rechargeable version of the CR123A, and it is often sold as RCR123A. It fits the same slot, but it runs at 3.6 volts against the CR123A's 3, and a freshly charged one is nearer 4.2. Some torches and cameras are built to accept either and say so. Many are not, and feeding one 4.2 volts can damage it. Check your manual before swapping — and never put a CR123A in a charger.
- Verdict:
- Same slot, different voltage — check the device is rated for both
- Interchangeable:
- no
These fit the same space but are not electrically compatible
The 16340 runs at 3.6 V against the CR123A’s 3 V — a 0.6 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 CR123A is also single-use: putting one in a charger built for the 16340 can make it vent, leak or catch fire.
Side-by-side specifications
| Specification | 16340 | CR123A |
|---|---|---|
| Chemistry | Li-ion | Lithium |
| Type | Cylindrical | Cylindrical |
| Nominal voltage | 3.6 V | 3 V |
| Diameter | 16 mm | 17 mm |
| Height | 34 mm | 34.5 mm |
| Typical capacity | 650–800 mAh | 1400–1600 mAh |
| Rechargeable | Yes | No |
| Also sold as | RCR123A, ICR16340, IMR16340 | CR17345, DL123A, EL123A, 123 |
Size comparison
Near enough to interchange by hand — 16 × 34 mm against 17 × 34.5 mm — which is precisely why the voltage difference matters here.
Rechargeable against single-use
The 16340 is lithium-ion and designed to be recharged. The CR123A is a primary lithium cell and must never go in a charger — doing so can make it vent or burst.
Voltage
3.6 V nominal for the 16340 against 3 V for the CR123A, and up to 4.2 V straight off the charger. Devices rated for both usually print it; treat silence as a no.
Runtime
650–800 mAh against 1400–1600 mAh. The single-use CR123A holds roughly twice as much per cell, which is why it stays the choice for smoke alarms and equipment left alone for years.
Read the device, not the size chart
Plenty of torches and some cameras explicitly accept both and regulate accordingly — the box or the manual will say. Plenty of others were designed around a flat 3 V and have no headroom. The footprint being identical is exactly why the manufacturer's statement is the only reliable guide.
Three volt rechargeables exist too
Some cells sold as RCR123A include a regulator that holds the output near 3 V rather than 3.6, specifically to be safe in CR123A equipment. They cost more and hold less. If you need a rechargeable in a device rated only for 3 V, that regulated type is the one to look for.
Why the CR123A survives
A primary lithium cell holds its charge for a decade and works in the cold, which is why smoke alarms, security cameras and emergency torches still specify it despite the cost per cell. For equipment that must work the one time you need it, that beats rechargeability.
Can I use a CR123A instead of a 16340?
No — and the fit will not stop you. The CR123A measures 17 × 34.5 mm against 16 × 34 mm, close enough that it will sit in the same compartment. The problem is electrical: 3.6 V against 3 V. Fitting the 16340 where the CR123A 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.
16340 vs CR123A: common questions
Is the CR123A a direct replacement for the 16340?
The 16340 is the rechargeable version of the CR123A, and it is often sold as RCR123A. It fits the same slot, but it runs at 3.6 volts against the CR123A's 3, and a freshly charged one is nearer 4.2. Some torches and cameras are built to accept either and say so. Many are not, and feeding one 4.2 volts can damage it. Check your manual before swapping — and never put a CR123A in a charger.
What is the difference between the 16340 and the CR123A?
The 16340 is a 3.6 V rechargeable lithium-ion cell in the CR123A's footprint. The CR123A is a 3 V single-use lithium cell. In short: same slot, different voltage — check the device is rated for both.
Are the 16340 and the CR123A the same size?
No. The 16340 is 16 × 34 mm and the CR123A is 17 × 34.5 mm.
Which lasts longer, the 16340 or the CR123A?
The CR123A. It is rated at 1400–1600 mAh against 650–800 mAh for the 16340 — roughly 2.1× the capacity, though real runtime depends on how much current your device draws.
Is the 16340 rechargeable?
Yes, and the CR123A is not. Never put a CR123A in a charger: single-use cells can vent, leak or catch fire when charged.
Background reading
The wider questions behind these two codes.