AA Batteries - Size, Types and Equivalents
AA batteries are one of the most common battery sizes used in household electronic devices.
AA batteries differ in used chemistry and hence the capacity, voltage, discharging characteristics and other features very important when powering sensitive electronic equipment.
AA batteries are cylindrical batteries 14.5 mm (0.57 inch) in diameter and 50.5 mm (1.99 inch) in length.
Their standard label is 'AA', but other labels are also in use, often depending on the country, chemistry, standard and similar, including: U12, HP7, Penlight, Mignon, MV1500, MN1500, MX1500, Type 316, LR6, 15A, R6, 15D, FR6, 15LF, etc.
The following table lists most common AA battery chemistries and their features, including their most important feature, AA battery voltage:
|Chemistry||Common Name||Rechargeable||Typical Capacity (mAh)||Voltage|
|Zinc - Carbon||R6, 15D||No||600 - 1600||1.5 V|
|Alkaline||LR6, 15A||No (Mostly No)||1800 - 2700||1.5 V|
|Li-FeS2||FR6, 15LF||No||2700 - 3300||1.5 V (1.8 V max)|
|Li-ion||14500||Yes||600 - 2000+||3.6 - 3.7 V|
|NiCd||KR6, 1.2K2||Yes||600 - 1000||1.2 V|
|NiMH||HR6, 1.2H2||Yes||700 - 2800||1.2 V|
|NiOOH||-||No||2200 - 2700||1.5 V (1.7 V max)|
|NiZn||ZR6||Yes||1500 - 1800||1.6 - 1.65 V|
As one can see in the table, AA batteries differ in chemistry, capacity, voltage, and other features, and 'the best of all', as time goes by, new battery types are introduced.
Fortunately, most common battery types are Alkaline (primary, non-rechargeable) and Nickel Metal Hydride (NiMH, secondary, rechargeable) batteries.
Primary, Non-Rechargeable AA Batteries
Primary, non-rechargeable AA batteries include Zinc Carbon, Alkaline, Li-FeS2 and NiOOH batteries.
Zinc Carbon AA batteries are older type of batteries, featuring nominal voltage of 1.5 V and typical capacity of 600 - 1600 mAh.
Actual capacity depends on the intended use of the battery (low drain, high drain) and the battery design.
Due to the slightly lower capacity, Zinc Carbon batteries are being replaced with Alkaline batteries.
Alkaline AA batteries are practically a standard AA batteries. They are based upon the reaction between zinc metal and manganese dioxide, they feature 1.5 V nominal voltage and capacity generally in the 1800 - 2700 mAh range.
When compared with Zinc Carbon batteries, the alkaline batteries have a higher capacity (hence higher energy density) and longer shelf-life, with practically the same voltage.
Note: specially designed alkaline batteries can be recharged numerous times, but these are not standard alkaline batteries. Often, they are labeled as RAM (Rechargeable Alkaline Manganese) batteries. Unless otherwise labeled, alkaline battery is primary, non-rechargeable battery.
NiOOH or Nickel Oxy-Hydroxide battery is variety of alkaline battery where nickel oxyhydroxide is added to the manganese dioxide and graphite for the cathode leading to the 1.5 V typical voltage during high drain use and 1.7 V maximum voltage.
NiOOH batteries have very similar capacity to standard alkaline batteries, but they can be drained using larger currents and are often used in high drain devices like cameras and similar.
Li-FeS2 or Lithium Iron Disulfide is type of non-rechargeable AA lithium battery featuring typical voltage of 1.5 V during high drain drain applications, but also up to 1.8 V maximum open-circuit voltage. Its typical capacity is in 2700 - 3300 range, providing excellent capacity and energy density for a non-rechargeable AA battery.
Li-FeS2 AA batteries are commonly used in high-drain devices like cameras, flashlights and similar.
When choosing the best AA primary battery, don't forget to take into account a type of device that you have - some devices will tolerate large input voltage differences, but some will not.
For short - if you need a good primary (non-rechargeable) AA battery, go for Alkaline AA battery from reputable brands. Such batteries provide stable voltage, long shelf-file, and good capacity at affordable price.
Rechargeable AA Batteries
Rechargeable AA batteries include batteries like NiCd, NiMH and Li-ion batteries.
NiCd or Nickel Cadmium batteries are older type of rechargeable batteries featuring 1.2 V nominal voltage and capacity of 600 - 1000 mAh.
NiCd batteries also feature strong memory effect, high self-discharge rate, but they are also able to provide strong currents without adverse effects on the batteries.
But, they also contain cadmium (heavy metal, dangerous pollutant), and are being phased out in the favor of NiMH batteries.
NiMH or Nickel Metal Hydride batteries feature nominal voltage of 1.2 V and typical capacity of 700 - 1500 mAh, with certain low drain models featuring capacity of up to, and even more than 2800 mAh.
Modern NIMH batteries have very low self-discharge rate, almost no memory effect (if any!), and output voltage more stable than NiCd batteries.
However, some models are optimized for high-drain use, while some models are optimized for high-capacity operation - thus, when choosing NiMH batteries, be sure to know required output current of your device(s).
AA Battery vs Lithium-ion 14500 Battery
14500 lithium ion batteries are rechargeable cylindrical batteries that are physically very similar to AA batteries.
They are based on one of many lithium ion batteries and feature typical voltage of 3.6 - 3.7 volts. Capacity significantly vary, depending on the intended use and other features present, from ~600 mAh to 2000 mAh or even more.
14500 batteries can be optimized for high-drain operations (but smaller capacity), for low-drain operations (but higher capacity) and for general use (balance between capacity and the maximum allowed output current).
Lithium-ion 14500 batteries and AA batteries are physically interchangeable, but the output voltage difference is rather large (3.6-3.7 volts vs 1.5 volts), which can lead even to the destruction (to say the least) of the user device.
Especially the devices intended to be powered via NiMH batteries should NOT be powered via 14500 batteries UNLESS explicitly stated by the device's manufacturer.
Some devices like advanced LED flashlights, photo cameras and similar allow the use of AA alkaline (1.5 V), AA NiMH (1.2 V) and 14500 batteries (3.6 - 3.7 V) batteries, but that is always clearly stated by the manufacturer.
Additional features of 14500 batteries may include:
- built-in protection electronics that monitor condition of the battery, protecting the battery from overheating, overcharging, over-discharging and similar events.
- built-in charger allows the charging of the individual batteries via micro-USB (or similar) charging port, simplifying the use, etc.
Such circuitry require some space, leading to smaller capacity, but additional features often justify drop in capacity.
Long Story Short: AA batteries are very common household type of batteries, with the dimensions of 14.5 × 50.5 mm (0.57 × 1.99 inches). Their most important types are:
- Alkaline: non-rechargeable, 1.5 V nominal voltage,
- NiMH: rechargeable, 1.2 V nominal voltage,
- Li-ion (14500): rechargeable, 3.6 - 3.7 V nominal voltage.
Again, if unsure, when buying new batteries, always go for the same battery type.