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, discharge characteristics, and other features that are very important when powering sensitive electronic equipment.
AA batteries are cylindrical batteries 14.5 mm (0.57 inches) in diameter and 50.5 mm (1.99 inches) 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 the most common AA battery chemistries and their features, including their most important feature, AA battery voltage:
|Chemistry||Common Name||Rechargeable||Typical Capacity (mAh)||Voltage (V)
|Zinc Carbon||R6, 15D||No||600 - 1600||1.5|
|Alkaline||LR6, 15A||No (Mostly No)||1800 - 2700||1.5|
|Li-FeS2||FR6, 15LF||No||2700 - 3300||1.5 (1.8 max)|
|Li-ion||14500||Yes||600 - 2000+||3.6 - 3.7|
|NiCd||KR6, 1.2K2||Yes||600 - 1000||1.2|
|NiMH||HR6, 1.2H2||Yes||700 - 2800||1.2|
|NiOOH||-||No||2200 - 2700||1.5 (1.7 max)|
|NiZn||ZR6||Yes||1500 - 1800||1.6 - 1.65|
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, the most common battery types are Alkaline (primary, non-rechargeable) and Nickel Metal Hydride (NiMH, secondary, rechargeable) batteries, but lithium AA batteries are coming on strongly.
Primary, Non-Rechargeable AA Batteries
Primary, non-rechargeable AA batteries include Zinc Carbon, Alkaline, Li-FeS2, and NiOOH batteries.
Zinc Carbon AA batteries are an older type of batteries, featuring a nominal voltage of 1.5 V and a 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 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, an alkaline battery is a primary, non-rechargeable battery.
NiOOH or Nickel Oxy-Hydroxide battery is a 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 a very similar capacity to standard alkaline batteries, but they can be drained using stronger currents and are often used in high drain devices like cameras and similar.
Li-FeS2 or Lithium Iron Disulfide is a type of non-rechargeable AA lithium battery featuring a typical voltage of 1.5 V during high drain applications, but also up to 1.8 V maximum open-circuit voltage. Its typical capacity is in the 2700 - 3300 mAh range, providing excellent capacity and energy density for a non-rechargeable AA battery.
Another very important feature of Li-FeS2 batteries is their extra long shelf life of up to 20 years, making them a popular choice for standby, medical, backup, security, EDC (Every Day Carry), and similar devices and applications.
Li-FeS2 AA batteries are commonly used in devices like cameras, flashlights, alarms, and similar.
When choosing the best AA primary battery, don't forget to take into account the type of device that you have - some devices will tolerate large input voltage differences, but some will not.
Lithium Thionyl Chloride (Li-SOCL2) battery is a type of non-rechargeable AA battery featuring a nominal voltage of 3.5-3.6 volts, OCV (Open Circuit Voltage) of ~3.65 volts, and nominal capacity of 2400-2700 mAh.
Lithium Thionyl Chloride (Li-SOCL2) AA batteries are not directly compatible with 1.5V AA batteries and should NOT be used in devices intended ONLY for 1.5V AA batteries.
Other than that, Lithium Thionyl Chloride (Li-SOCL2) AA batteries feature very good energy density and extra long shelf life of 10-20 years.
Lithium Manganese Dioxide (Li-MnO2) battery is a type of non-rechargeable AA battery featuring a nominal voltage of 3.0 volts, a cutoff voltage of 2.0 volts, and a typical capacity of 2000 mAh.
Typical labels of Lithium Manganese Dioxide (Li-MnO2) battery include 14505, CR AA, and similar.
Lithium Manganese Dioxide (Li-MnO2) battery features a long shelf life of up to or even more than 10 years.
Also, modern CR AA batteries don't contain harmful chemicals or heavy, toxic metals like cadmium, lead, mercury, and similar.
Due to its 3.0V voltage, CR AA batteries should NOT be used in devices intended ONLY for 1.5V AA batteries.
For short - if you need a good primary (non-rechargeable) AA battery, go for an Alkaline AA battery from reputable brands. Such batteries provide stable voltage, long shelf-file, and good capacity at an affordable price.
Rechargeable AA Batteries
Rechargeable AA batteries include batteries like NiCd, NiMH, and Li-ion batteries.
NiCd or Nickel Cadmium batteries are an older type of rechargeable batteries featuring 1.2 V nominal voltage and a capacity of 600 - 1000 mAh.
NiCd batteries also feature a 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 a nominal voltage of 1.2 V and a typical capacity of 700 - 1500 mAh, with certain low drain models featuring a capacity of up to, and even more than 2800 mAh.
Modern NIMH batteries have a 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 the 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 a typical voltage of 3.6 - 3.7 volts. Capacity significantly varies, 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 the 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 a micro-USB (or similar) charging port, simplifying the use, etc.
Such circuitry requires some space, leading to smaller capacity, but additional features often justify a drop in capacity.
Long Story Short: AA batteries are a very common type of battery, with the dimensions of 14.5 × 50.5 mm (0.57 × 1.99 inches). Their most important types are:
- Alkaline: non-rechargeable, 1.5V nominal voltage,
- Li-FeS2: non-rechargeable, 1.5V nominal voltage,
- NiMH: rechargeable, 1.2V nominal voltage,
- Li-ion (14500): rechargeable, 3.6 - 3.7V nominal voltage.
Again, if unsure, when buying new batteries, always go for the same battery type.