In this paper, we reported measures against spike noises in a charger circuit of the micro-satellite "TSUB AME" which has high power consumption (MAX 68W). The spike noises occurred from an FET as a switching regulator in the Li-ion battery charger circuit. The main cause of the spike noises was pattern design and another cause was that choices of FET and inductor weren't optimal. Thus, by major upgrade of EPS circuits, the inductor is changed to another inductor which the self-resonant frequency is higher than frequencies of the spike noises, and the FET is also changed to an FET with low reverse recovery current. As a result, there are no spike noises in the charger circuit.