Orbital performance of AMPTE/CCE nickel-cadmium batteries with a large number of charger-induced, very small, charge/discharge cycles

The AMPTE/CCE spacecraft used switching regulators to short-circuit the excess solar array current and control the charge to each of its two 28 V, 4 Ah nickel-cadmium batteries. This digital regulation of the battery overcharge current caused approximately 10 × 106, very small battery charge/discharge cycles during the long sunlight periods of the highly elliptical, 24 h orbit; a unique system influence that did not significantly degrade battery performance during the mission life. The occurence of three very long eclipses at the beginning, middle and end of the mission, provided a rare opportunity to analyze the performance of the batteries for the mission life. This paper presents the power system design, and the battery performance for about five years of mission life.