Within the joint CNES-ESA 'ELAN' programme, which has been running for six years, nickel-cadmium batteries are cycling under various low-earth-oribt (LEO) conditions. No sudden cell failures have occurred, but all cells in the battery subjected to the most severe conditions (25 Cel, 40 % DoD) have reached the end of life criterion for end of discharge voltage. Capacity retention was poor and teardown analysis revealed a loss of negative plate capacity and extensive cadmium migration into the separator. The remaining 20 batteries continue cycling. Initial lifetime expectations have been considerably surpassed. The so-called 'memory effect' is very evident and long term as well as short term beneficial effects of both shallow and deep reconditioning are evident. In the absence of reconditioning memory effects are likely to determine the useful lifetime of a battery on board a spacecraft. In the case of a battery subjected to a simulated ERS-1 spacecraft load profile, reconditioning after two years has allowed a second two year period of life to be sustained. This has important implications for the management of batteries for future LEO missions such as the Columbus Polar Platform.
Update on low-earth orbit nickel-cadmium battery lifetime testing
Aktualisierung des Wissenstandes über Untersuchungen zur Batterielebensdauer von Nickelcadmiumzellen für den Einsatz im erdnahen Orbit
Proceedings of the European Space Power Conference ; SP-320 ; 303-308
1991
6 Seiten, 10 Bilder, 4 Tabellen, 4 Quellen
Aufsatz (Konferenz)
Englisch
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