Internal impedance of nickelcadmium batteries with applications to space

A study of the internal impedance of a 7 A h, SAFT VO7S4, NiCd battery cycled under low earth orbit conditions at high current rates and low temperatures is presented. The tested battery consist of three cells selected from a group of fifty well matched cells. The study presents a relationship between the battery internal impedance, the state of charge and the operating temperature. This relationship may be used as an indicator for the battery state of charge during missions in space.