Selecting recharge protocols for deep-discharge nickel-hydrogen cells and batteries

An ongoing study within The Aerospace Corporation has been the review of the nickel-hydrogen life cycle testing programs being conducted by several organizations. The overall objective of the study has been to review the database information that is available as it relates to missions requiring long cycle life at deep depths of discharge (DOD), and from this study to develop a knowledge base that can be applied to these advanced missions. In addition to this database review, earlier studies by other investigators are examined as they relate to changes in the charging potential of the nickel electrode caused by changes in the level of cobalt additive in the active material. Coordinated post-test analyses carried out on selected cells in the authors' laboratories are presented as they relate to establishing conditions where the cycle life can be increased while at the same time increasing the DOD to which the cells are cycled.