A battery system for an body stabilized satellite traveling in a geosynchronous orbit comprises east and second battery modules and similarly facing radiators for discharging beat to deep space. Heat conduction arteries connect each battery module to its associated radiator. An east thermal switch is operable for thermally connecting the first battery module to and from the east facing radiator. Similarly, a west thermal switch is operable for thermally connecting the second battery module to and from the west facing radiator. A computer selectively operates the east and west thermal switches such that, in one instance, for a time between the satellite's emergence from the earth's shadow and its position nearest the sun, the respective thermal switches thermally connect the first battery module to its radiator while thermally disconnecting the second battery module from its radiator. In another instance, beginning when the satellite is nearest the sun and ending as it enters the earth's shadow, the east thermal switch thermally disconnects the first battery module from its radiator while the west thermal switch thermally connects the second battery module to its radiator. In still another instance, beginning when the satellite is in the shadow of the earth, the battery modules are simultaneously thermally connected to their associated radiators. Charging of each battery proceeds while it is thermally connected to its respective radiator.