Coin cell

Overview
A Coin cell also known as a button cell or watch battery is a battery package shaped as a thin cylinder ranging from about 1-6mm tall and 5-25mm in diameter. These cells are typically used to power low-power electronics such as wrist-watches an calculators, or as backup power devices such as CMOS on motherboards. Most coin-cell batteries have a low self-discharge and therefore will retain their charge for long period is left unused. However, some specialty variants exist such as zinc-air batteries which have a small shelf-life but provide a higher energy density to higher-power devices such as hearing-aids.

Cells of similar size can frequently be switched out. However, variants do exist, and different constructions may mean a difference in overall power output and/or lifespan.

Technical Details
Button cells tend to be disposable, non-rechargeable batteries. Anodes are typically formed from zinc or lithium with manganese dioxide, silver oxide, or carbon monofluoride cathodes, although there are numerous variants such as the sue of oxygen by zinc-air batteries.

Cells are typically formed from a circular cap for the anode surrounded by an insulating cap, then surrounded with a formed cathode cat that forms the outer circumference and opposite side of the cell.

Watch batteries typically conform to a nomenclature consistent with International standard IEC 60086-3.

Letter Codes (first letter)

Size Codes (first one or two numbers)

The following number will be the battery width in millimeters x 10-1

So as an example, the common CR2032 battery is a Lithium/manganese dioxide running at at 3V with dimensions of 20mm and is 3.2mm tall.

Links

 * IEC 60086-3 standard