Batteries are available in many different shapes and sizes. The size of a battery often depends on the device it is designed to power. Small devices such as watches use tiny batteries, while larger electronic devices require batteries with greater capacity.
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In this article, we’ll look at some of the most common battery sizes that you’ll encounter in everyday electronics.
Button cells (Coin cells)
Button cells, also known as coin cells, are small, round batteries that resemble a coin. They are much thinner than their diameter, which makes them ideal for compact electronic devices.
Most button cells consist of a single electrochemical cell, which is why they are technically called cells rather than batteries. Many are non-rechargeable, although rechargeable versions are also available.
Because of their small size and low power consumption, button cells are commonly used in:
- Wrist watches
- Calculators
- Car key fobs
- Motherboard CMOS memory
- Hearing aids
These devices consume very little power, allowing a single button cell to last for months or even years.
Cylindrical batteries
Cylindrical batteries are the most familiar type of battery. They have a round shape with a height greater than their diameter and are widely used in household electronics.
You’ll commonly find them in devices such as:
- TV remote controls
- Wall clocks
- Wireless keyboards and mice
- Flashlights
- Toys
Cylindrical batteries are available in both primary (non-rechargeable) and secondary (rechargeable) versions.
For most primary batteries, such as alkaline cells, the nominal voltage is around 1.5 V, while rechargeable versions like NiMH cells typically have a nominal voltage of 1.2 V.
Common cylindrical battery sizes
Cylindrical batteries are available in several standardized sizes. Some of the most common are:
- AAAA
- AAA
- AA
- C
- D
Among these, AA and AAA batteries are by far the most widely used.
The names simply indicate the physical size of the battery.
An AAAA battery is the smallest of these common sizes. It is often used in laser pointers, stylus pens, and other compact electronic devices.
A AAA battery is larger than an AAAA battery but smaller than an AA battery. It is commonly used in TV remotes, wireless mice, and small portable devices.
An AA battery is one of the most popular battery sizes. It is used in flashlights, toys, cameras, clocks, and countless other electronic products.
Although AA and AAA batteries usually have the same nominal voltage, an AA battery is physically larger and therefore stores more energy. As a result, it generally lasts much longer than a AAA battery under the same operating conditions.
Rectangular batteries
As the name suggests, rectangular batteries have a rectangular shape. The most common example is the 9 V battery.
These batteries are commonly used in:
- Smoke detectors
- Multimeters
- Toys
- Audio equipment
- Electronics projects
A 9 V battery has two snap terminals on the top.
The smaller circular terminal is the positive terminal, while the larger hexagonal terminal is the negative terminal. A battery snap connector is commonly used to connect the battery to electronic circuits.
Many 9 V primary batteries are internally made from six 1.5 V cells connected in series, although rechargeable and lithium-based versions are also available.
Rechargeable battery packs
Many modern electronic devices use custom-shaped rechargeable battery packs instead of standard battery sizes.
For example, smartphones typically use flat rectangular lithium-ion or lithium-polymer batteries that are designed specifically for the phone.
Similarly, DSLR cameras use specially designed battery packs that fit securely into the camera’s battery compartment. The shape of these batteries ensures they can only be inserted in the correct orientation while also providing a compact and reliable power source.