Abstract: A highly efficient battery charging system in which the ampere-hour discharge of the battery is sensed for controlling the battery charging rate. The battery is charged at a relatively high charge rate during a first time period proportional to the extent of battery discharge and at a second lower rate thereafter.

Abstract: A satellite power system in which solar cells provide power to a load during sunlight hours and also charge, through regulators, rechargeable batteries which provide power during dark periods. In order to prevent the batteries from being overcharged by solar cell current bypassing the regulators (through the load connection) each battery is protected by a redundant protection system including a pair of diodes and switch means normally connecting one of the diodes between the battery and the load. If the one diode fails or shorts, the switch means connects the other diode between the battery and the load; the voltage across the one diode and current therethrough are sensed to determine if the diode has failed.