AA battery

The AA battery (or double-A battery) is a standard size single cell cylindrical dry battery. The IEC 60086 system calls the size R6, and ANSI C18 calls it 15.^[1] It is named UM-3 by JIS of Japan.^[2] Historically, it is known as D14 (hearing aid battery),^[3] U12 – later U7 (standard cell), or HP7 (for zinc chloride 'high power' version) in official documentation in the United Kingdom, or a pen cell.^[4]

AA batteries are common in portable electronic devices. An AA battery is composed of a single electrochemical cell that may be either a primary battery (disposable) or a rechargeable battery. Several different chemistries are used in their construction. The exact terminal voltage, capacity and practical discharge rates depend on cell chemistry; however, devices designed for AA cells will usually only take 1.2–1.5 V unless specified by the manufacturer.

Introduced in 1907 by The American Ever Ready Company,^{[5][third-party source needed]} the AA battery size was standardized by the American National Standards Institute (ANSI) in 1947, but it had been in use in flashlights and electrical novelties before formal standardization. ANSI and IEC battery nomenclature gives several designations for cells in this size, depending on cell features and chemistry. Before being called AA batteries, they were commonly called Z batteries, as the ones produced by the Burgess Battery Company were sold as "Number Z" (meant to indicate them being smaller than the "Number 1", which was similar in size to a modern C battery).^{[citation needed]} Due to their popularity in small flashlights, they are often called "penlight batteries".