C/DPV nickel-hydrogen batteries

Advanced Battery Technology,  Apr 2003  

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The term "common/dependent pressure vessel" (C/ DPV) denotes a proposed alternative configuration for a nickel-hydrogen battery. The C/DPV is a hybrid of the "common pressure vessel" and "dependent pressure vessel" configurations, reports NASA Tech Briefs. It has been proposed as a basis for designing highly reliable, long-life Ni/IH^sub 2^batteries and cells for anticipated special applications in which it is expected that small charge capacities will suffice and sizes and weights must be minimized.

The figure depicts examples of the proposed C/DPV configuration along with the CPV and DPV configurations and the two other prior configurations called "individual pressure vessel" (IPV) and "single pressure vessel" (SPV).

The following characteristics of the prior configurations are particularly relevant to the proposal of the C/DPV configuration. A DPV has a pocket-watch shape that is both advantageous and disadvantageous, in comparison with the shapes of the IPV, CPV, and SPV. The advantage is that a battery or cell can be made relatively flat and thin to fit in a thin space; the disadvantage is that a pressure vessel of this shape is not self-supporting and therefore must be mounted between objects that restrain it. DPV cells have not been widely used. The SPV and CPV configurations have been the basis of the established method for designing pressure vessels containing multiple cells.

Like the CPV and SPV configurations, the CIDPV configuration is one of multiple cells contained within a DPV. This would afford the advantages and disadvantages of the DPV configuration (thinness and the need for mechanical restraint, respectively), while making it possible to use an electrolyte containment system like that of the SPV. Although it is not readily apparent by visual examination, calculations have shown that for a given small charge capacity, the volumetric efficiency of a battery in the C/DPV configuration would exceed the volumetric efficiencies of batteries in the other configurations mentioned. Other anticipated advantages of the C/DPV configuration include improved thermal properties, greater simplicity and reliability (in comparison with the SPV configuration), lower costs associated with the simpler designs, and amendability to replacement and matching of cells.

This work was done by Paul J. Timmerman of Caltech for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free online at www.nasatech.com/tsp under the Computers/Electronics category.

Copyright Seven Mountains Scientific, Inc. Apr 2003
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