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What are the parts of a cordless power tool battery?

What are the parts of a cordless power tool battery?

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Battery parts of a power tool rechargeable, secondary battery: catch, release button, cell casing, contacts, power tool attachment.


Contacts allow electricity to pass from the battery to the power tool. 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.
Exposed and covered contacts of a cordless power tool battery. Some contacts are exposed while others have plastic barriers which help protect them from damage and short circuiting.
self cleaning double contacts of a cordless power tool battery. 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

Slide-on battery pack for a cordless power tool. 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.’
Slot-in battery pack to a cordless power tool. The other design uses a slot-in or ‘post’ style mechanism.


The catches hold the battery in place once the battery is fitted in the power tool. The catch, usually made from a durable plastic, holds the battery in place once it is fitted to the cordless power tool.

Release button

Release button releases the catch allowing the battery to be removed from the power tool. To remove the battery from the cordless power tool, the catch must be released using the release button.

Cell casing

Empty casing of a rechargeable battery pack. 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.

Printed information

Printed information on a battery of a cordless power tool. The printed information on a battery provides important information about the battery’s chemistry, voltage and capacity as well as safety and maintenance information, usually provided using symbols (see What do the symbols on cordless power tool batteries and chargers mean?)


Screws hold all the parts of a rechargeable power tool battery in place. The screws hold the components and the two halves of the cell casing together.
Inside a cordless power tool battery there are battery cells, foam padding and a circuit board.

Circuit board

Circuit board used to make up battery side of circuit. 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.


Battery cells store electricity for use in circuits. 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

Foam is used to pad cells to prevent them from getting damaged in the battery during use. 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.

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