An AAA or triple-A battery is a standard size of dry cell battery commonly used in low drain portable electronic devices. A triple-A battery is a single cell and measures 44.5 mm in length and 10.5 mm in diameter. The length includes the positive terminal button which is a minimum 0.8 mm high and 3.8 mm in diameter; the flat negative terminal has a minimum diameter of 4.3 mm. Alkaline AAA batteries weigh around 11.5 grams each, while primary lithium AAA Batteries weigh about 7.6 g. Rechargeable nickel–metal hydride (NiMH) AAA Batteries typically weigh 14–15 g.
An AA battery is a standard size single cell cylindrical dry battery. An AA battery is composed of a single electrochemical cell that may be either a primary battery (disposable) or a rechargeable battery. The exact terminal voltage and capacity of an AA size battery depends on cell chemistry. An AA cell measures 49.2–50.5 mm (1.94–1.99 in) in length, including the button terminal—and 13.5–14.5 mm (0.53–0.57 in) in diameter. The positive terminal button should be a minimum 1 mm high and a maximum 5.5 mm in diameter, the flat negative terminal should be a minimum diameter of 7 mm. Alkaline AA cells have a weight of roughly 23 g (0.81 oz), lithium AA cells have a mass around 15 g (0.53 oz), and rechargeable Ni-MH cells around 31 g (1.1 oz).
Rechargeable batteries in the AA size are available in multiple chemistries: nickel–cadmium (NiCd) with a capacity of roughly 600–1000 mAh, nickel–metal hydride (NiMH) in various capacities of 1300–3500 mAh and lithium ion. Lithium ion chemistry has a nominal voltage of 3.6 volts. They are referred to as 14500 Li-ion batteries.
A CR123 battery is always Li-MnO2 ('lithium') chemistry, in addition to its unique size. A lithium primary battery, not interchangeable with zinc types. A rechargeable lithium-polymer version is available in the same size and is interchangeable in some uses. According to consumer packaging, replaces (BR)2/3A. In Switzerland as of 2008, these batteries accounted for 16% of lithium camera battery sales. Used in flashlights. The dimensions of CR123 battery is 34.5 mm in length and 17 mm in diameter.
18650 is a Lithium-Ion battery. Lithium-ion cells are made in various sizes, often assembled into packs for portable equipment. Many types are also available with an internal protection circuit to prevent over-discharge and short-circuit damage. Normally, The dimensions of 18650 battery is 65.2 mm in length and 18.6 mm in diameter, but may be around 68 mm long with an internal protection circuit.