Battery is a device that converts chemical energy directly into electrical energy. Batteries are used to power a variety of devices, including radios, automobile starters, and electronic equipment on satellites. Tiny batteries, such as those used in hearing aids, are less than 0.2 inch (6 millimeters) in diameter and weigh 1/100 ounce (0.3 gram). The largest batteries, such as those that power submarines, can weigh over 100 tons (90 metric tons). A backup system called an uninterruptible power supply (UPS) uses batteries to maintain power during a utility power failure. A UPS enables computers, emergency lights, and hospital equipment to continue operating if a power loss occurs.
Batteries are manufactured in a wide range of sizes and shapes. The International Electrotechnical Commission, based in Geneva, Switzerland, sets standard sizes and minimum performance specifications for many batteries. The basic dimensions of such common sizes as D, C, AA, and AAA are thus consistent from manufacturer to manufacturer, regardless of the country in which the batteries are made. Such standardization helps ease world trade in electrical and electronic products.
