In this paper, we review our work on cycle-life testing of a 100-Ah class lithium-ion battery in a simulated geosynchronous-Earth-orbit (GEO) satellite operation. The battery consists often 100-Ah lithium-ion (10) cells in a series, with a high energy density exceeding 100 Wh kg L at the battery level. We simulate the eclipse period in real-time testing with five depth-of-discharge (DOD) patterns at an ambient temperature of 15 degrees C. We also simulate a sun-shine period in 8-day thermally accelerated full-charge storage at an ambient temperature of 25 degrees C, which in our experience corresponds to full-charge storage of a half-year operation at 0 degrees C. Eighteen eclipse seasons have presently been completed, corresponding to 9 years of GEO operation. The battery maintained a high voltage near 3.4 V at the end of the discharge, even when the DOD was set at 70%. The voltage dispersion of 10 cells was also sufficiently small in the range of 48 mV The cell temperature reached a maximum of 29 degrees C and maintained minimal dispersion smaller than 4 degrees C even when the battery was discharged at a high DOD of 70%. (c) 2006 Elsevier B.V All rights reserved.