Nickel-Cadmium Cells for the Spacecraft Battery

The storage battery for the Telstar satellite m ust undergo frequent chargedischarge cycles; in addition, it is subject to overcharge during a substantial portion of its life. Nickel-cadmium cells were chosen as best capablc of satisfactory long-time operation under these conditions. A design and selection program was undertaken to ensure that Ni-Cd cores would meet objectives imposed by battery service conditions, and- the cell enclosure ivas designed to minimize electrolyte leakage. Selection, qualification, and life tests indicated that a storage battery using the cell design would perform satisfactorily. To date, the only failures occurring during continuing life tests have been among cells subjected to 100 per cent discharge daily; this operation is far in excess of the expected duty cycle of satellite cells.