D battery: 33.2 mm. in diameter x 61.5 mm. long. Minimum capacity (alkaline): 12,000 mAh

Was once commonly used in large flashlights, lanterns, and children’s toys.

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C battery: 26.2 mm. in diameter x 50 mm. long. Minimum capacity (alkaline): 10,000 mAh

Was once commonly used in large and small flashlights and children’s toys.

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B battery: 21.5 mm. in diameter x 60 mm. long. Minimum capacity (alkaline): 8,000 mAh

Used in the UK and the Russian Federation as the internal cells of 4.5-volt lantern batteries.

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A battery: 17 mm. in diameter x 50 mm. long. Minimum capacity (alkaline): 4,900 mAh

Not commonly available as a primary (non-rechargeable) battery. Sometimes encountered as a rechargeable battery in battery packs.

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AA battery: 14.5 mm. in diameter x 50.5 mm. long. Minimum capacity (alkaline): 1,800 mAh

Still in widespread use. Commonly available in alkaline, carbon-zinc, nickel-metal-hydride, and nickel-cadmium varieties. Used for small portable devices like flashlights and portable electronics.

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AAA battery: 10.5 mm. in diameter x 44.5 mm. long. Minimum capacity (alkaline): 860 mAh

Still in widespread use. Commonly available in alkaline, zinc-carbon, nickel-metal-hydride, and nickel-cadmium varieties. Used for small portable devices like small flashlights, small portable electronics, and electronics with a low current draw.

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AAAA battery: 8.3 mm. in diameter x 42.5 mm. long. Minimum capacity (alkaline): 500 mAh

Available, but not in common use. Used for slim-profile electronics such as laser pointers and penlights.

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AAAAA battery: 7 mm. in diameter x 39.9 mm. long. Minimum capacity (alkaline): 330 mAh

Briefly considered for use in endoscopic surgical equipment in the early 1980s, because of its narrow profile, but rejected due to the risk of electrolyte leakage within patients.

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AAAAAA battery: 5.6 mm. in diameter x 37.6 mm. long. Minimum capacity (alkaline): 190 mAh

Developed in the USSR in the mid-1970s, to be used as both the projectile and the power source for the guidance system in AK-48 cartridges. Saw limited mass-production, and continued to be used following the collapse of the USSR. Was rendered entirely obsolete by the development of the Zorg ZF-1 in 1997.

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AAAAAAAAAA: 2.3 mm. in diameter x 29.5 mm. long. Minimum capacity (alkaline): 19 mAh

Showed promise powering ultra-portable and ingestible electronic devices. However, manufacturer Varta produced a battery in this size with the name shortened to A10, which resulted in a trademark dispute with Fairchild, manufacture of the A-10 “Warthog” attack aircraft, and caused Varta and other manufacturers to cease production out of fear of litigation.

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AAAAAAAAAAAAAAA: 0.8 mm. in diameter x 21.8 mm. long. Minimum capacity (alkaline): 1 mAh

Not in common use, but favored by some for electric mechanical pencils, being about the same size as a pencil lead.

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AAAAAAAAAAAAAAAAAAA: 0.31 mm. in diameter x 17.1 mm. long. Minimum capacity (alkaline): 0.11 mAh

Fell out of favor in the 1980s because it was frequently mistaken for a 30-gauge hypodermic needle. Was banned in the early 1990s after it was discovered teenagers were using them to inject themselves with intravenous POWER.

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AAAAAAAAAAAAAAAAAAAAAAAAA: 0.085 mm. in diameter x 11.88 mm. long. Minimum capacity (alkaline): 0.00038 mAh

Were briefly considered for portable power applications in the 1980s, since they could easily be disguised as strands of hair, but were never mass-produced due to their low capacity.

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AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA: 0.0093 mm. in diameter x 6.48 mm. long. Minimum capacity (alkaline): 0.000013 mAh

Were briefly believed to be the power source for human cells, until the discovery of the mitochondrion in 1898.

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AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA: 0.001 mm. in diameter x 3.7 mm. long. Minimum capacity (alkaline): 0.00000000015 mAh

Were most likely first observed in 1943 in a bacterial mat from the northern part of the Dead Sea. Were misidentified as “funny-looking bacteria” until 2003.

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AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA: 0.000010 mm. diameter x 0.65 mm. long. Minimum capacity (alkaline): 0.00000000000049 mAh

Showed promise as a power source for ultraminiature cassette players in the 1980s, but fell out of favor due to its physical resemblance to particles of Ebola virus.

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AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA: 0.0000000054 mm. in diameter x 0.13 mm. long. Minimum capacity (alkaline): 0.000000000000000000001 mAh

An alkaline AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA battery manufactured by Panasonic held the world record for smallest alkaline battery from its introduction in 1990 until 2004. In 2004, it was discovered that the battery’s nominal diameter was smaller than that of a hydrogen atom, and its capacity was fifty times smaller than the fundamental charge of an electron. The battery was stricken from the record books for being “physically impossible”. Panasonic retired this battery size the following year.

This entire post is a work of fiction. Any resemblance to real persons or entities is coincidental.