10440 vs AAA
The 10440 is an AAA-sized 3.6 V lithium-ion cell. The AAA is 1.5 V alkaline. Same footprint, incompatible electrically.
Last reviewed
A 10440 looks like an AAA and fits like an AAA, but it is a rechargeable lithium-ion cell at 3.6 volts where the AAA is alkaline at 1.5. More than double the voltage, in a cell that slides into the same slot. Fitting one in an ordinary AAA device can destroy it. Only use a 10440 in equipment that names it specifically.
- Verdict:
- AAA-shaped, 3.6 V — not a substitute
- Interchangeable:
- no
These fit the same space but are not electrically compatible
The 10440 runs at 3.6 V against the AAA’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 AAA is also single-use: putting one in a charger built for the 10440 can make it vent, leak or catch fire.
Side-by-side specifications
| Specification | 10440 | AAA |
|---|---|---|
| Chemistry | Li-ion | Alkaline |
| Type | Cylindrical | Cylindrical |
| Nominal voltage | 3.6 V | 1.5 V |
| Diameter | 10 mm | 10.5 mm |
| Height | 44 mm | 44.5 mm |
| Typical capacity | 300–350 mAh | 850–1200 mAh |
| Rechargeable | Yes | No |
| Also sold as | ICR10440 | LR03, MN2400, AM4, R03 |
Size comparison
Near enough to interchange by hand — 10 × 44 mm against 10.5 × 44.5 mm — which is precisely why the voltage difference matters here.
Why the sizes match
10 mm across and 44 mm long, against 10.5 × 44.5 mm for an AAA. The numbering describes the dimensions, which is why Li-ion cells shadow the household sizes so closely.
The voltage gap
3.6 V nominal, up to about 4.2 V fully charged, against a flat 1.5 V. Very few devices built for an AAA tolerate that.
Small cell, real hazard
At 300–350 mAh the 10440 holds little energy, but lithium-ion cells this small still vent violently if over-discharged or charged on the wrong charger. Treat it as equipment, not as a household battery.
The same trap in a smaller package
Everything true of the 14500 against an AA applies here: an AAA-shaped cell at more than double the voltage, in a size that fits ordinary household devices. The smaller capacity makes it no safer — a vented 10440 is still a lithium cell failing in your hand.
Runtime is genuinely short
At 300–350 mAh, a 10440 in a bright torch can be flat in twenty minutes. Enthusiasts accept that for the brightness a 3.6 V cell allows in a keychain light. It is not a cell you fit and forget.
Charging is not optional equipment
A 10440 needs a lithium-ion charger that handles cells this small, and many multi-bay chargers have a minimum current too high for it. Charging one on an unsuitable setting is a real hazard rather than a theoretical one.
Can I use an AAA instead of a 10440?
No — and the fit will not stop you. The AAA measures 10.5 × 44.5 mm against 10 × 44 mm, close enough that it will sit in the same compartment. The problem is electrical: 3.6 V against 1.5 V. Fitting the 10440 where the AAA 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.
10440 vs AAA: common questions
Is the AAA a direct replacement for the 10440?
A 10440 looks like an AAA and fits like an AAA, but it is a rechargeable lithium-ion cell at 3.6 volts where the AAA is alkaline at 1.5. More than double the voltage, in a cell that slides into the same slot. Fitting one in an ordinary AAA device can destroy it. Only use a 10440 in equipment that names it specifically.
What is the difference between the 10440 and the AAA?
The 10440 is an AAA-sized 3.6 V lithium-ion cell. The AAA is 1.5 V alkaline. Same footprint, incompatible electrically. In short: aAA-shaped, 3.6 V — not a substitute.
Are the 10440 and the AAA the same size?
No. The 10440 is 10 × 44 mm and the AAA is 10.5 × 44.5 mm.
Which lasts longer, the 10440 or the AAA?
The AAA. It is rated at 850–1200 mAh against 300–350 mAh for the 10440 — roughly 3.2× the capacity, though real runtime depends on how much current your device draws.
Is the 10440 rechargeable?
Yes, and the AAA is not. Never put a AAA 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