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Eight 72 Ah nickel/hydrogen variant cell designs are currently undergoing LEO life testing at Space Systems/Loral. 2000 - 35% DOD LEO cycles have been completed to date. The variant designs incorporate various positive electrode parameters, stack designs, KOH concentration, and platinized/non-platinized wall wicks. BOL data indicates that observed variant performance differences are valid. Observations of effects of the selected parameters on cell performance will be statistically examined as part of continued cell evaluation. The life test is planned to continue for greater than five years.

The 75 Ah actively cooled bipolar battery continues to undergo LEO life testing at 40% DOD and to date has completed 13,000 cycles. The EOC and EOD voltages indicate that there is slight degradation in the overall battery performance. The primary influence in this decline is considered to be one cell's poor performance. The potential for extended cycle life capability of bipolar batteries has been demonstrated. Ten 4-cell passively cooled bipolar batteries are on test at Space Systems/Loral (SS/L). Characterization testing has been completed. The results indicate that high capacity utilizations can be maintained at various discharge rates. Performance differences were noted and seem to be related to battery design variations. Further testing is planned.