Autor: |
Hobbs, B. S., Keily, T., Palmer, A. G. |
Zdroj: |
Journal of Applied Electrochemistry; July 1979, Vol. 9 Issue: 4 p501-510, 10p |
Abstrakt: |
The volumetric energy density picture is explored for nickel-cadmium cells in a single duty cycle application, over the operational temperature range -30 to +55° C. Results are presented showing that fresh, precycled cells easily attain the target specification (40–50 W h dm-3) at temperatures at and above room temperature. Charge acceptance falls sharply at sub-zero temperatures however, and energy density reduces to critical levels below -20° C. The charging characteristics and ability to achieve target performance at -30° C depends markedly on cell origin and the permissibility of allowing some cell venting during the charge. The low temperature limitations can be overcome by means of low wattage heating coils on the cells. Internal temperatures of C and D/2 cells can be raised to 20° C within a few minutes by employing very modest temperature gradients and with heater volumes no greater than the manufacturers label and sleeve. Although the picture is optimistic for fresh precycled cells, major problems are anticipated with stored cells, particularly at temperature extremes, unless steps can be taken to prevent or erase storage effects. |
Databáze: |
Supplemental Index |
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