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. According to a 2005 estimate, the worldwide battery industry generates US$48 billion in sales each year, with 6% annual growth.
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 hearing aids and wristwatches; larger batteries provide standby power for telephone exchanges or computer data centers.
The name "battery" was coined by Benjamin Franklin for an arrangement of multiple Leyden jars (an early type of capacitor) after a battery of cannons. Strictly, a battery is a collection of two or more cells, but in popular usage battery often refers to a single electrical cell.
An early form of electrochemical battery called the Baghdad Battery may have been used in antiquity.] However, the modern development of batteries started with the Voltaic pile, invented by the Italian physicist Alessandro Volta in 1800.