What Is a Coin Cell Battery?
A coin cell battery is a thin, small, coin-shaped battery. It takes very little space and provides a low current for a long time.
Naming
In codes like CR2032 the letters indicate the chemistry (CR = lithium) and the numbers the size: "20" means the diameter is 20 mm, "32" means the thickness is 3.2 mm. So the code directly gives the dimensions.
| Type | Voltage | Use |
|---|---|---|
| CR2032 | 3V (lithium) | Motherboard RTC, remote control |
| LR44 | 1.5V (alkaline) | Calculator, toy |
Why Is It Used?
Being very small, it's ideal in space-limited places. Thanks to its low self-discharge, it lasts for years in very low-current applications.
RTC Backup
Its most common use is to power the real-time clock (RTC) and settings while the motherboard is off. Even when the device is unplugged, the clock doesn't stop thanks to this battery.
Where Is It Used?
Motherboards (BIOS/RTC), remote controls, wristwatches, calculators, hearing aids and small IoT sensors.
Life and Self-Discharge
A coin cell's strongest point is its low self-discharge: it drains very little while sitting unused, so it's ideal for low-current tasks lasting years like an RTC. But its voltage collapses on jobs needing high instantaneous current; it's suited only to low-current applications.
Common Mistakes
- Expecting high current: a coin cell is for low current, it can't drive a motor/power.
- Short circuit: leaving it on a conductive surface leads to draining/heating.
- Swallowing risk: a serious danger for children, access must be prevented.
Frequently Asked Questions
How many volts is a CR2032?+
Why is it in a computer?+
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