An extensive test frogram was initiated at Martin Mareitta Space Systems to establish a low-earth-orbit (LEO) data base for nickel-hydrogen, individual pressure vessel (IPV) cells. The main okject of this test program was to determine whether or not a 10/spl deg/C, 40% DoD LEO test regime could be supported for 20,000 cycles. Eighty-two nickel hydrogen cells with a name plate capacity rating of 50 ampere-hours were initially procured. Actual testing was initiated in 1985. Since then, an additional twenty-four 50 ampere-hour cells and twenty-one 100 ampere cells have been added to the test program totaling 127 cells. Four separate vendors, were selected for cell procurement: Eagle Picher, Joplin Missouri, Eagle Picher, Colorado Springs, Colorado, Yardney Technical Products, Pawcatuck, Connecticut; Gates Energy Products, Gainesville, Florida. Cells on test include 50 ampere-hour Air Force design, 100 ampere-hour Air Force design, 50 ampere-hour COMSAT design, and 50 ampere-hour MANTECH design. The majority of cells on test contained a 31% KOH concentration at activation although 9 cells were activated using a KOH concentration of 26%. An additional 6 cells were supplied which maintain a 31% KOH concentration under life test. Cycles completed range from 511 to over 20,000 with 35 cell failures primarily in the 60% DoD test groups. Two of the 35 failures were due to mechanical failure and not a result of LEO cycling. This paper is intended to present an overview of the Nickel-Hydrogen LEO test Program, the present status as of May 1990, and cell failures resulting from LEO cycling. Destructive physical analysis results will also be discussed.
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