Abstract. Ni-Cd battery is the key component of the satellite energy system with the characteristics of long life and high reliability, and few or no failure occurs in its traditional life testing. In this paper, based on the performance degradation modeling method, we establish a dynamic degradation model to capture the evolution of the end of discharge voltage (EODV), which is a function of cycle number and temperature. Two methods are utilized to assess the reliability of Ni-Cd battery. Results show that the random effect regression method obtains a more conservative reliability estimation result that the pseudo life based method does.