90-ampere-hour nickel-hydrogen dependent pressure vessel (DPV) low Earth orbit (LEO) life test evaluation

Three 90-Ah dependent pressure vessel (DPV) battery packs are being LEO life tested at Crane. As of 9/10/01, the 40% DOD pack has completed 4863 total cycles, and the 60% DOD pack has completed 2885 total cycles. The third pack, formerly tested at 71% DOD but currently run at 60% DOD, had 2067 total cycles as of 9/24/01. The philosophy of these tests is to minimize charging to maximize life, so all the packs started with low charge-discharge (C/D) ratios. As a result, the charge conditions of the packs, especially the two 60% DOD packs, have been changed to find the appropriate operating points for these cells and packs.