Aircraft storage batteries

LEAD-ACID, nickel-cadmium, and silver-zinc storage batteries have been used, or have been proposed for use, on commercial and military aircraft. Each one of these electrochemical systems has characteristics that recommend it for service in aircraft. Lead-acid batteries, dating from the double-chamber Mark 1¿7 series, have been used for a long time in such service and are well adapted to the conventional electric circuits used in airplanes. Nickel-cadmium batteries may be ¿hermetically¿ sealed, an obviously desirable characteristic, and exhibit good outputs over a wide range of discharge rates. Silver-zinc batteries give high electrical output per unit weight and volume, a most desirable characteristic for aircraft where weight and volume are at a premium. Recently, a fourth system, the silver-cadmium battery, has been proposed but insufficient data are presently available to predict its over-all performance.