page_title: AA battery
section_title: Rechargeable cells
hierarchical_section_title: AA battery / Chemistry and capacity / Rechargeable cells
caption_attribution_description: English: Panasonic's fourth-generation Eneloop batteries, in AA and AAA sizes.
context_page_description: The AA battery, also called a double A, penlite or Mignon battery, is a standard size single cell cylindrical dry battery. The IEC 60086 system calls it size R6, and ANSI C18 calls it size 15. It is named UM-3 by JIS of Japan. Historically, it is known as D14 or HP7 in official documentation in the United Kingdom.
  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 or a rechargeable battery. Several different chemistries are used for 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, the AA battery size was standardized by the American National Standards Institute 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.
context_section_description: 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 600–2750 mAh and lithium-ion.
  Lithium ion chemistry has a nominal voltage of 3.6–3.7 volts, and are referred to as 14500 Li-ion batteries rather than AA.
  NiMH and Lithium Ion AA/14500 cells can supply most of their capacity even when under a high current drain (0.5A and higher), unlike Alkaline and Zinc-chloride("Heavy Duty"/"Super Heavy Duty") cells which drop to a small fraction of their low current capacity before even reaching 1 C.
  A variant of the 14500 Li-ion batteries, sold by the Chinese company Kentli as "Kentli PH5" since 2014, comes with an internal buck converter at the positive electrode to downstep the output voltage from the normal 3.7 V to a very consistent (compared to alkaline, NiCd, or even NiMH cells) 1.5 V AA standard voltage. It exposes the normal 3.7 V Li-ion electrode in a ring around the AA electrode for charging. Its more regular voltage provides better drop-in compatibility for alkaline AA devices, and its lithium-ion chemistry provides a lower self-discharge at 3% per month. It holds a mediocre capacity of 1600 mAh (1.5 V) at 50 mA drain, limited by the low efficiency of the step-down converter.
  Nickel-zinc cell (NiZn) AAs are also available, but not widely used.
caption: Panasonic Eneloop 1.2 volt NiMH rechargeable batteries in AA and AAA
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