A battery technology that provides more charge per pound or size than nickel cadmium or nickel metal hydride without suffering from the memory effect. It uses a carbon membrane that absorbs oxygen, a zinc plate and potassium hydroxide as the electrolyte. The technology dates back to the 1920s, when large batteries were used for remote railroad switches and lights on harbor buoys.
Air causes the chemical reaction and must be allowed into the cell when current is required and kept out when not. Thus, zinc air batteries are designed for continuous use. For example, when used for hearing aids, once activated, the zinc air battery continuously discharges.
The pioneer in air management technology was AER Energy Resources Inc. AER's Diffusion Air Manager provided an economical method for getting air in and out, but the company closed its doors in 2003 after more than a decade of development. Used extensively in the military, security and transportation sectors, a leading producer of zinc air batteries is the Electric Fuel division of Arotech (www.electric-fuel.com). See batteries
Keeping the Air Out
AER's patented Diffusion Air Manager used a tiny fan to force air in when a device needed power, and inlet and exit tubes kept the air out when the load was removed. (Image courtesy of AER Energy Resources, Inc.)