# Power Density

## What is Power Density?

Power density is the amount of power per unit of volume that a device contains. A unit of volume expressed as watts per cubic meter.

Key Takeaways:

• Power density is the amount of power per unit of volume that a device contains.
• Power density is often measured as watts per cubic meter.
• Power density is not as common as energy density, but is still a useful term.

## Understanding Power Density

Power density is a unit of volume that measures the amount of power per unit of volume that a device contains. When measuring something like a battery or fuel cell, power density is measured as watts per cubic meter. In the case of an internal combustion engine, power density is measured based on the internal capacity of the engine, not its external size.

If a system has a high power density, it can expend large amounts of energy as a proportion to its size. For example, a small capacitor may have a larger output of energy as a large battery if its power density is greater.

Common metrics used for power density are: watts per cubic meter, watts per kilogram, and horsepower per cubic inch.

Power density is not as common of a measurement as energy density, but is still useful for conversations about portable energy systems.

## Related Terms

Power – A form of measurement used in electrical systems that denotes the rate per unit of time at which electricity is transferred through an electrical system.

Battery Cycle Life – The typical number of charge and discharge cycles that a battery can undergo before it reaches the end of its useful life.

Nominal Voltage – The stated voltage at which a device is safe to operate without damage to the system.