Button Cell (Coin Cell)

Overview

Button cells maybe also be known as coin cells or watch batteries.

Polarity

The insulated top cap of a button cell is the negative terminal, the base is the positive terminal.

Internal Resistance

The internal resistance of a coin cell battery starts of at a rather large 10Ω. This then rapidly increases as the batteries energy is consumed. Where high pulse currents are needed, coin cell batteries can be used in conjunction with high-valued capacitors.

A rule of thumb for coin cell batteries is that 10mA is the maximum current draw.

Technologies

Silver Cell

Silver cells have a very stable output voltage over the lifespan of the battery.

Common Types

CR2032. CR2025.