AA battery

Published: 07th September 2009
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An AA battery (pronounced "double a" English pronunciation: /ˈdʌbəl ˈeɪ/) is a dry cell-type battery commonly used in portable electronic devices. The AA battery type was standardized by ANSI in 1947, and is designated E91 by DIN and AM3 by JIS. Internationally the IEC designated it as LR6 (alkaline), R6 (carbon-zinc), KR157/51 (nickel-cadmium), HR6 (nickel-metal-hydride), and FR6 (lithium-iron-disulfide). Other names include MN1500 and HP7. In China it is known as the #5 battery. In Germany it is known colloquially as Mignon. An AA battery is composed of a single electrochemical cell.

4.5-Volt, D, C, AA, AAA, 9-Volt, SR41/AG3, SR44/AG13 cells

An AA battery measures 51 mm in length (50.1 mm without the button terminal), 13.5-14.5 mm in diameter,[1] (1.97×0.56 inches). Traditional alkaline AA batteries have mass of roughly 23 g (0.81 oz), Lithium AA batteries have mass around 15 g (0.5 oz), and rechargeable NiMH batteries have mass about 31 g (1.1 oz).

The nominal output voltage of single-use AA batteries is 1.5 volts, while NiCd and NiMH rechargeable batteries have a nominal voltage of 1.2 V. Specialty batteries based on more unusual chemistries can run at a voltage as high as 1.6 V under load.[2] The voltage of a AA battery is the same as a AAA battery, C cell or D cell. AA batteries, however, provide power for a longer period than AAA batteries, because their larger size allows them to store a greater mass of anode material which is consumed as it does electrical work. C and D cells, being larger, last longer still; as a rough guide, the capacity of a battery scales linearly with its mass.

Primary (non-rechargeable) zinc-carbon AA batteries of 400-900 milliamp-hours capacity are commonly made using Leclanché cell technology. Zinc-chloride batteries of 1000 to 1500 mAh are often sold as "long life" or "heavy duty". Alkaline batteries from 1700 mAh to almost 3000 mAh cost a little more, but last proportionally longer.

Single-use (ie. non-rechargeable) lithium batteries are also available for high demand devices such as digital cameras, where their high cost is offset by longer running time between battery changes. As of 2008, the only 1.5 V lithium AA called "Ultimate Lithium", is manufactured by Energizer, although AA-sized batteries with different nominal voltages are available from others. These should only be used in devices rated for the higher voltage.

Inside a ZnC battery

The formerly common zinc-carbon or zinc-chloride AA battery consists of a graphite rod in the center forming an electrode, an anode/electrolyte mix consisting mainly of manganese oxide, a zinc outer shell which serves as the cathode, and a paper, plastic or steel cover. See Zinc-carbon battery. There is sometimes a pressure valve at the bottom to prevent explosions. However, this generally will not prevent leakage or catastrophic failure of the shell if the battery is exposed to fire or extreme heat.

If a Zn-C or Zn-Cl battery is discharged too far, corrosion of the cathode, which is the zinc shell, can occur. If it becomes corroded enough, a breach in the shell can allow electrolyte to leak out. This is a common cause of damage to battery-powered appliances which are left unattended for long periods with batteries inside. The electrolyte can also cause minor skin damage, and should be kept away from eyes, and not ingested.

Inside an alkaline battery

More common today than the lower cost ZnC batteries are alkaline cells. Different variants exist, offering roughly two to three times the capacity of ZnC cells. Rather than zinc chloride as the electrolyte, potassium hydroxide is used.

We hope the article helped you understand and gain knowledge about an AA battery.

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