AAA Batteries - Size, Chemistry Types and Replacements

AAA batteries are one of the most common cylindrical battery sizes used in various electronic and electric devices, like remote controls, toys, cameras, flashlights, radios etc.

AAA batteries differ greatly in chemistry and hence they differ in capacity, voltage, current/voltage discharging characteristics and many other features, which may be of great importance when powering sensitive electronic equipment.

energizer alkaline aaa

AAA Battery Dimensions, Features and Specifications

AAA batteries are cylindrical batteries 10.5 mm (0.41 inch) in diameter and 44.5 mm (1.75 inch) in length.

Their standard label is 'AAA', but other labels are also in use, often depending on the country, chemistry, standard and similar, including: LR03, R03, FR03, HR03, KR03, ZR03, 24A, 24D, 24LF, MN2400, MX2400, MV2400, Type 286, U16, HP16, UM 4, etc.

But, practically all most important battery brands label them as AAA batteries.

The following chart lists most common AAA battery chemistries, labels and their features, including perhaps their most important features, AAA battery voltage and capacity:

Chemistry Common Name Rechargeable Typical Capacity (mAh) Voltage
Zinc Carbon R03, 24D No 500-600 1.5 V
Alkaline LR03, 24A Mostly No 850-1200 1.5 V
Li-FeS2 FR03, 24LF No 1100-1300 1.5 V (1.8 V max)
Li-ion 10440 Yes 350-600 3.6 - 3.7 V
Lithium - Yes 400-600 1.5 V
NiCd KR03, 24K Yes 300-500 1.2 V
NiMH HR03, 24H Yes 600-1300 1.2 V
NiOOH ZR03 No 1000-1200 1.5 V (1.7 V max)

Although AAA batteries features vary greatly depending on the chemistry type, the most important AAA batteries are non-rechargeable alkaline AAA batteries and NiMH rechargeable AAA batteries.

However, with the advances in technology and chemistry, new types are gaining in popularity as well.

Non-Rechargeable (Primary) AAA Batteries

Non-rechargeable (primary) AAA batteries include Zinc Carbon, Alkaline, Li-FeS2 and NiOOH batteries.

Zinc Carbon AAA batteries are somewhat older type of primary batteries, featuring nominal voltage of 1.5 V and typical capacity of 500-600 mAh.

Zinc Carbon AAA batteries where very popular AAA battery chemistry, but due to their lower capacity, these batteries are almost fully replaced by alkaline AAA batteries.

duracell niooh aaaAlkaline AAA batteries are practically a standard chemistry type of AAA batteries.

They also feature nominal voltage of 1.5V and larger capacity of 850 - 1200 mAh.

When compared with Zinc Carbon batteries, the alkaline AAA batteries have a higher capacity and higher energy density, with longer shelf-life, with some brands offering up to 10+ years shelf life.

Note: most alkaline batteries are non-rechargeable (primary) batteries. But, specially designed AAA alkaline batteries can be recharged numerous times, although these are not standard alkaline batteries. Unless otherwise labeled, alkaline AAA battery is primary, non-rechargeable battery.

NiOOH or Nickel Oxy-Hydroxide AAA battery is type of alkaline battery where nickel oxyhydroxide is added to the manganese dioxide, leading to the 1.5 V typical voltage during high drain use and 1.7 V maximum voltage.

NiOOH AAA 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.

energizer aaa lithiumLi-FeS2 or Lithium Iron Disulfide is type of non-rechargeable AAA lithium battery featuring 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 1100 - 1300 range, providing high capacity and energy density.

Li-FeS2 AAA batteries are commonly used in high-drain devices like cameras, flashlights, high-end toys and similar.

Thanks to their ultra-long shelf/standby life (up to 20+ years!), Li-FeS2 batteries are recommended for devices and applications that are used rarely/in standby, but they must be powered with reliable power source, even after years (decades!) of non-use.

When choosing the best AAA 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) AAA battery, go for Alkaline AAA battery from reputable brands. Such batteries provide stable voltage, long shelf-file, and good capacity at affordable price.

Rechargeable (Secondary) AAA Batteries

Rechargeable AAA batteries include battery chemistry types like Nickel-Cadmium (NiCd), Nickel-Metal-Hydride (NiMH) and various lithium ion batteries.

Nickel Cadmium AAA batteries are older type of rechargeable batteries featuring 1.2 V nominal voltage and capacity of 300 - 500 mAh.

These batteries feature strong memory effect and rather high self-discharge rate. However, NiCd batteries are also able to provide strong currents without adverse effects on the batteries.

On the other hand, NiCd batteries also contain cadmium (heavy metal, dangerous pollutant), and are being phased out in the favor of more environment friendly NiMH batteries.

eneloop aaa 800mahNickel Metal Hydride AAA batteries feature nominal voltage of 1.2 V and typical capacity of 600 - 1300 mAh. Their nominal capacity and maximum allowed drain current greatly depend on the battery type (low drain, high-capacity or high drain, lower capacity).

Modern NiMH batteries have very low self-discharge rate, with almost no memory effect, and with output voltage more stable than the output voltage of older NiCd batteries.

For example, Panasonic Eneloop 800 mAh AAA batteries hold 90% of charge after 1 year of storage, 80% after 3 years, 75% after 5 years and even 70% after 10 years of storage, making them suitable even for standby applications and may be recharged 2100+ times.

Also, Panasonic Eneloop Pro AAA batteries hold for example, 85% of charge after 1 year, but their capacity is 950 mAh and may be recharged 500+ times.

Both NiCd and NiMH batteries feature lower voltage when compared with Zinc-Carbon and Alkaline AAA batteries (1.2 vs 1.5 volts), but most electronic devices are designed to be powered by either 1.2 or 1.5 volts batteries.

Just to be sure, before switching from 1.5 to 1.2V or from 1.2 to 1.5 volts, check the manual of your device - better safe than sorry :)

Lithium ion AAA or 10440 batteries are rechargeable cylindrical batteries that are physically very similar to AAA batteries.

10440 lithium ion batteries feature diameter of 10.0 mm (vs 10.5 mm of AAA battery) and height of 44 mm (vs 44.5 mm of AAA battery) - thus, terms 10440 batteries or lithium-ion rechargeable AAA batteries are used interchangeably.

There are generally two types of lithium rechargeable batteries:

- lithium ion AAA batteries with the output voltage of 3.6-3.7 volts (or 3.2-3.7 volts) and maximum charging voltage of 4.2 volts. These batteries include IMR (LiMn204 - Lithium Manganese Oxide), INR (LiNiMnCoO2 - Lithium Manganese Nickel), IFR (LiFePO4 - Lithium Iron Phosphate), ICR (LiCoO2 - Lithium Cobalt Oxide) or some other similar/hybrid (LiNiCoO2 - Lithium Nickel Cobalt Oxide, LiNiCoAlO2 - Lithium Nickel Cobalt Aluminum Oxide, etc.) technology.

Typical capacity of Lithium ion AAA batteries is in the 350-600 mAh range, but it also depends on the battery design (high capacity, low drain current or lower capacity, higher drain currents).

Unless explicitly stated by their manufacturers, devices/appliances/toys designed for 1.2-1.5 volt AAA batteries should NOT be powered by the 3.2-3.7 lithium ion AAA batteries.

usb rechargeable 1 5 v aaa

- lithium rechargeable AAA batteries with the output voltage of 1.5 volts and capacity of 400-600 mAh. These batteries features Battery Management Systems (BMS) that ensure stable output voltage of 1.5 volts, and protects the battery from overcharging, over-current, high and low temperature operations and similar.

As such, they may be used as direct replacement for 1.5 volts Zinc-Carbon or Alkaline batteries. Also, most of these batteries feature micro-USB charging connector and may be charged directly.

AAA Batteries vs 18650 Batteries

samsung inr18650 25r battery

At first, AAA and 18650 batteries don't have much in common - AAA batteries are cylindrical batteries 10.5 mm (0.41 inch) in diameter and 44.5 mm (1.75 inch) in length, while 18650 batteries are cylindrical batteries 18.6 mm (0.73 inch) in diameter and 65.2 mm (2.56 inch) in length.

18650 batteries are lithium-ion rechargeable batteries with nominal voltage of 3.2-3.7 volts and maximum charging voltage of 4.2 volts and nominal capacity of 1500 - 5000 mAh (depending on the battery type and design).

On the other hand, three AAA batteries connected in series feature 3.6 volts (NiCd or NiMH) to 4.5 volts (Zinc-Carbon, Alkaline).

aaa battery holder

Certain devices are designed to be powered by either one 18650 battery or by 3xAAA batteries, using special battery holder.

Although such devices offer great flexibility when choosing the batteries, 18650 battery easily outperforms 3xAAA batteries in terms of power - some 18650 batteries may easily provide 30+ Amps of current.

On the other hand, some EDC (Every Day Carry) devices like flashlights that are rarely used, but must be powered with reliable batteries after years of storage, they should be powered by Li-FeS2 AAA batteries featuring up to 20+ years shelf/standby life.

If your device may be powered by both AAA or 18650 batteries, choose according to your own personal needs.


duracell coppertop alkaline aaaLong Story Short: AAA batteries are very common household type of batteries, with the dimensions of 10.5 × 44.5 mm (0.41 × 1.75 inches). Their most important types are:

- Alkaline: non-rechargeable, 1.5 V nominal voltage,

- NiMH: rechargeable, 1.2 V nominal voltage,

- Lithium: rechargeable 3.6 (3.2) - 3.7 V or rechargeable 1.5 V nominal voltage.

If You are unsure if your device supports other battery types, when buying new batteries choose the same battery type as you had before - again, better safe than sorry.