Long life communication satellites: Electric power supply during the eclipse period

The electric batteries, essentially nickel-cadmium for French satellites such as D1 A, D1 C, D1 D, D2 B, D5 A, D5 B, etc. and the batteries for such satellites as Symphonie, ANS, INTASAT, ESRO 4, and COS-B are discussed. The experience obtained led to the development of long lifetime batteries for communication satellites. Real simulation tests showed a lifetime of four years and accelerated lifetime tests of twelve years. These batteries will be applied in OTS, METEOSAT, and Marots. At the same time, new batteries are being developed, based on nickel-hydrogen or on silver-hydrogen, which should provide longer lifetime and better reliability.