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.

Updated: October 19, 2021.

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 the most common AAA battery chemistries, labels, and their features, including perhaps their most important features, AAA battery voltage, and capacity:

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 a nominal voltage of 1.5 V and a typical capacity of 500-600 mAh.

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

Alkaline AAA batteries are practically a standard chemistry type of AAA batteries.

They also feature a nominal voltage of 1.5V and a 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, the alkaline AAA battery is a primary, non-rechargeable battery.

NiOOH or Nickel Oxy-Hydroxide AAA battery is a 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 a 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 a type of non-rechargeable AAA 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 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 a reliable power source, even after years (decades!) of non-use.

When choosing the best AAA 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.

For short - if you need a good primary (non-rechargeable) AAA battery, go for an Alkaline AAA battery from reputable brands. Such batteries provide stable voltage, long shelf-file, and good capacity at an 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 an older type of rechargeable batteries featuring 1.2 V nominal voltage and a capacity of 300 - 500 mAh.

These batteries feature a strong memory effect and a 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 environmentally friendly NiMH batteries.

Nickel Metal Hydride AAA batteries feature a nominal voltage of 1.2 V and a 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 a 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 a 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 an output voltage of 3.6-3.7 volts (or 3.2-3.7 volts) and a 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.

The typical capacity of the 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.

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

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

AAA Batteries vs 18650 Batteries

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 inches) in length, while 18650 batteries are cylindrical batteries 18.6 mm (0.73 inches) in diameter and 65.2 mm (2.56 inch) in length.

18650 batteries are lithium-ion rechargeable batteries with a nominal voltage of 3.2-3.7 volts and a maximum charging voltage of 4.2 volts and a 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).

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

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Long Story Short: AAA batteries are a 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.