Life testing of secondary silver-zinc cells for the orbiting maneuvering vehicle

Over the past 5 years, extensive testing has been performed at the Marshall Space Flight Center (MSFC) on a variety of secondary (rechargeable) silver-zinc (Ag-Zn) cells for the Orbital Maneuvering Vehicle (OMV). The first tests performed were to determine the feasibility of using such a cell in a long-life (18-month), low-Earth-orbit (LEO) application. Results from these tests were promising, so testing continued with a 250-Ah cell that was specifically designed for this type of application. Once again, results from the tests were promising. Following a review of the data from these previous tests, slight modifications to the 250-Ah design were necessary to alleviate problem areas. Currently, MSFC is testing a 350-Ah design that has incorporated these changes and is the baseline design for the OMV. This test began in mid-November, 1989, and will be complete in the spring of 1991, barring any substantial offline time. A report is presented on the preliminary results from the first few months of this test and they are compared to results obtained in previous tests done at MFSC.