Battery AAA vs AA Energy

AAA vs AA battery energy

A typical alkaline AAA cell holds something like 1,000-1,200 mAh. The alkaline AA next to it carries 2,500-3,000 mAh, so at the same 1.5 V you're looking at roughly 2-3x more energy in the bigger size. Go to lithium AA and capacity climbs past 3,000 mAh, with a noticeable edge in the cold. The rechargeable NiMH AA lands around 2,000-2,500 mAh, but at 1.2 V.

Take a 4-pack of alkaline AA: that works out to about 4 · 2,800 mAh · 1.5 V ≈ 16.8 Wh. The same four cells in AAA land near ~6.6 Wh.

Applications

Use it to match the cell to what the device actually asks for. A remote or a clock barely sips current, so AAA is fine there. Motorized toys, flashlights and a camera flash pull hard, and those want AA. The numbers also help when you're working out cost per kWh, weighing alkaline against lithium and NiMH, or just deciding which size to buy when the gadget accepts either.

FAQ

Same voltage, different capacity, why? Both alkaline cells sit at 1.5 V. The AA just packs more chemistry inside, so it holds more charge (mAh).

Can I swap AAA for AA with an adapter? It fits, sure. But all you get is the AAA's capacity; the rest of the AA shell is hollow.

Are lithium batteries always better? They run longer and shrug off the cold, but they also cost 3-5x as much. In a low-drain device that money is mostly thrown away.