Primary and Secondary Cells and Batteries

Battery Applications & Technology

Batteries are either primary  or secondary. Primary batteries can be used only once because the chemical reactions that supply the electrical current are irreversible. Secondary (or storage) batteries can be used, charged, and reused. In these batteries, the chemical reactions that supply electrical current are readily reversed so that the battery is charged.

Primary batteries are common since they are cheap and easy to use. Familiar primary battery uses are in flashlights, watches, toys, and radios. The most common use for secondary (storage) batteries is for starting, lighting, and ignition (SLI) in automobiles and engine-generator sets. Other applications include uninterruptible power supplies (UPSs) for emergency and backup power, electric vehicles (traction), telecommunications, and portable tools.