40WhAkku

40WhAkku is a term used to describe a rechargeable battery pack with a nominal energy capacity of 40 watt-hours. It indicates the amount of energy the pack can deliver from full charge to depletion, with the precise voltage and chemistry determining the physical size and weight.

Most 40 Wh packs use lithium-ion or lithium-polymer chemistry. The cells are arranged in series and parallel to reach an appropriate nominal voltage and the target 40 Wh, and a battery management system monitors temperature, voltage, and state of charge.

Applications are typically in mid-sized portable devices and lightweight backup power. A 40 Wh pack can power devices for several hours depending on load, and in some systems it serves as an auxiliary or replacement energy source rather than a primary pack.

Charging, cycle life, and safety are important considerations. Li-ion packs commonly support charging rates around 0.5C to 1C; typical cycle life ranges from several hundred to about a thousand cycles, with capacity fading over time. Safety features include overcharge, over-discharge, short-circuit protection, and thermal management.

Regulatory standards for Li-ion packs cover safety testing and transport rules, such as IEC 62133 and UN 38.3, and batteries are typically shipped with a qualified protection circuit and labeling.

See also: lithium-ion battery, energy storage, battery pack.