FCL7

PRIMARY BATTERIES
The primary battery is a convenient source of power for portable electric and electronic devices, lighting, photographic equipment, PDA’s (Personal Digital Assistant), communication equipment, hearing aids, watches, toys, memory backup, and a wide variety of other
applications, providing freedom from utility power. Major advantages of the primary battery are that it is convenient, simple, and easy to use, requires little, if any, maintenance, and can be sized and shaped to fit the application. Other general advantages are good shelf life, reasonable energy and power density, reliability, and acceptable cost.
Primary batteries have existed for over 100 years, but up to 1940, the zinc-carbon battery was the only one in wide use. During World War II and the postwar period, significant advances were made, not only with the zinc-carbon system, but with new and superior types of batteries. Capacity was improved from less than 50 Wh/kg with the early zinc-carbon batteries to more than 400 Wh/kg now obtained with lithium batteries. The shelf life of batteries at the time of World War II was limited to about 1 year when stored at moderate temperatures; the shelf life of present-day conventional batteries is from 2 to 5 years. The shelf life of the newer lithium batteries is as high as 10 years, with a capability of storage at temperatures as high as 70oC. Low-temperature operation has been extended from 0 to 40oC, and the power density has been improved many fold. Special low-drain batteries using a solid electrolyte have shelf lives in excess of 20 years.