The nickel-cadmium battery is a popular type of rechargeable battering using the nickel hydroxide and metallic cadmium as the active chemicals. The principle advantages of NiCd over other rechargeable types is lower weight for a given quantity of stored energy, good charging efficiency, small variation in terminal voltage during discharge, low internal resistance, and non-critical charging conditions.
Sealed NiCd cells may be used individually, or assembled into battery packs containing two or more cells.
Small NiCd dry cells are used for portable electronics and toys, often using cells manufactured in the same sizes as primary cells. When NiCds are substituted for primary cells, the lower terminal voltage and smaller amperehour capacity may reduce performance over primary cells.
NiCd batteries have a niche market in the area of cordless and wireless telephones, emergency lighting, model airplanes, as well as power tools and electronic hand-held pleasure devices.
With a relatively low internal resistance, a NiCd battery can supply high surge currents. This makes them a favorable choice for remote controlled electric model aeroplanes, boats and cars, as well as cordless power tools and camera flash units