An electrical battery is a combination of one or more electrochemical cells, used to convert stored chemical energy into electrical energy. Since the invention of the first Voltaic pile in 1800 by Alessandro Volta, the battery has become a common power source for many household and industrial applications, and is now a multi-billion dollar industry.

Batteries may be used once and discarded, or recharged for years as in standby power applications. Miniature cells are used to power devices such as wristwatches and portable electronic devices; larger batteries provide standby power for telephone exchanges or computer data centers.