Single pressure vessel life test update [Ni-H/sub 2/ aerospace batteries]

Eagle-Picher Technologies (EPT) nickel-hydrogen batteries and battery cells have been subjected to many and vaned life cycle tests. Both real time and accelerated tests in low Earth orbit as well as geosynchronous Orbit test regimes have been performed. In most cases, these tests attempt to represent the on-orbit charge/discharge profile of the application as closely as possible, as well as test for extreme conditions. This test database was originated in support of early nickel-hydrogen flight program and has been consistently expanded over the past twenty years. Several new nickel-hydrogen cell and battery designs are on test including the single pressure vessel (SPV). Even though the basic stack components are very similar to traditional cells designs, such as the independent pressure vessel (IPV), the packaging concept for this battery is significantly different and thus requires additional life testing. There are currently two SPV batteries on life test at EPT. The 50Ah, 22 volt battery has accumulated 27,723 cycles at 30% depth of discharge (DOD). The 60Ah, 22 volt battery has accumulated 24,705 cycles, at 26% DOD. Both batteries are showing stable performance and are projected to deliver cycle life performance similar to IPV cells.