NASA Technical Reports Server (NTRS) : Capacity pdf

NASA Technical Reports Server (NTRS) : Capacity

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This viewgraph presentation discusses the following topics: 1) Capacity walkdown defined and illustrated; 2) Importance of capacity walkdown: 3) Four approaches to understanding the phenomenon – Pressure Trend, Charging Curve, Electrochemical Voltage Spectroscopy, and Destructive Physical Analysis Studies; 4) Results of the interrelated studies; 5) Suggested mechanism for capacity walkdown; and 6) Charging protocols to avoid the problem. In summary: 1) capacity walkdown is a consequence of the inability to maintain a high state of charge; 2) Capacity loss is typically 35% which would be expected by the valence difference between gamma and beta nickel oxyhydroxide; 3) Cycling at -5 degrees facilitates the formation of the gamma phase; 4) Excessive overcharge can also facilitate gamma phase formation at the expense of cycle life; and 5) Conditions can now be suggested to help minimize capacity walkdown

• Creator/s: NASA Technical Reports Server (NTRS
• Date: 3/1/2001
• Year: 2001
• Book Topics/Themes: NASA Technical Reports Server (NTRS), NICKEL HYDROGEN BATTERIES, ELECTRIC CHARGE, LOW EARTH ORBITS, CYCLES, VALENCE, Thaller, Lawrence H., Zimmerman, Albert H., To, Gloria

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