Nickel-cadmium cell separator life test

Results of tests on two identical groups of 26.5 Ah (nameplate) aerospace-type NiCd battery cells, carried out to determine the effect of separator material on cell performance, are presented. One 11-cell group employs the standard separator material Pellon 2505 ML, and the second group employs an industry-recommended substitute, Pellon 2536. The two cell groups, designed for low-Earth-orbit (LEO) application, are being tested in series at a temperature of 4°C. To ensure identical test conditions, a single test chamber is employed. The NiCd separator life test began in mid-1985; thus far, 10500 cycles have been completed. Ten cells have been removed for various reasons, and testing continues on the six remaining cells in each group. Variations in cell voltage have been measured in several cells containing the new separator material. However, in most cases, examination of dissected cells have not revealed the cause of their performance variations. The authors describe the life test, the results of cell dissections completed to date, and analyses performed thus far. Theories are offered to explain the performance anomalies that have been observed