The contacts, or ‘terminals,’ of the battery are made from a conductive metal and allow the electricity to flow out of the battery and into the tool to power it.
Some contacts are exposed while others have plastic barriers which help protect them from damage and short circuiting.
Some batteries have double contacts which keep themselves clean. This feature helps to keep the battery performing well because clean contacts make it easier to transmit power between the battery and cordless power tool or charger.
Power tool attachment
There are two ways that a cordless power tool battery can attach to a power tool. One design uses a slide-on mechanism. The power tool attachment of this design is sometimes called the ‘tongue.’
The other design uses a slot-in or ‘post’ style mechanism.
Catch
The catch, usually made from a durable plastic, holds the battery in place once it is fitted to the cordless power tool.
Release button
To remove the battery from the cordless power tool, the catch must be released using the release button.
Cell casing
The cell casing is made from plastic, a non-conductive material. It provides the structural support for the battery cells and circuit as well as the shape for the power tool attachment and covers for the contacts. It is made from two parts.
The screws hold the components and the two halves of the cell casing together.
Circuit board
The circuit board inside a battery controls the battery, At it’s simplest it makes up the electrical circuit between battery and cordless power tool. The most complicated circuit boards include computer chips which store battery information and monitor its performance.
Cell
A cordless power tool battery stores its electricity in cells. Each cell contains the components to create electricity (see How does a cordless power tool battery work?). A cordless power tool battery contains multiple cells, anything from 8 to 24. A battery with multiple cells is known as a battery pack.
Foam padding
The cells are fragile so are packed into the cell casing with foam padding to help prevent damage. Some battery packs use a more sophisticated suspension mechanism to prevent damage to the cells.
