Accession Number : AD0461856

Title :   CELL EQUALIZATION TECHNIQUES.

Descriptive Note : Technical rept.,

Corporate Author : MALLORY (P R) AND CO INC BURLINGTON MA

Personal Author(s) : Cocca, F. ; Amsterdam, R.

Report Date : FEB 1965

Pagination or Media Count : 59

Abstract : The utilization of stabistors for the protection of 4 AH, 5 AH, 12 AH and 20 AH Ni-Cd sealed cells has resulted in a definite increase in battery life. These cells were operated at a 90-minute cycle and at a depth of discharge of 75%. The results obtained from cycling 20 AH Ag-Cd and 25 AH Ag-Zn cells at a two-hour cycle revealed that stabistor protection of these cells was less effective than the protection offered Ni-Cd cells. Reversal studies on Ni-Cd cells show that the critical reverse gassing voltage for most NiCd cells was about -0.2 volts. The anti-reversal diode was partially successful in protecting cells on reversal. The thermal characteristics of the stabistor were improved by the use of molybdenum backing plates. These disks have a coefficient of expansion very close to that of silicon and increase the stabistors resistance to 'thermal fatigue' failure. Environmental testing of stabistors resulted in no failures after subjecting the devices to the required acceleration, vibration and shock tests. The 'end of contract' cells have been constructed with the stabistor and anti-reversal diode potted as part of the cell. Two different types of epoxy packages were constructed and the one that was chosen had a significantly lower temperature rise. (Author)

Descriptors :   *BATTERY COMPONENTS, *STORAGE BATTERIES, PERFORMANCE(ENGINEERING), PERFORMANCE(ENGINEERING), ALKALINE BATTERIES, SEMICONDUCTOR DEVICES, LIFE EXPECTANCY(SERVICE LIFE), NICKEL, CADMIUM, SEMICONDUCTOR DIODES, SILVER, ZINC, CONTROL SYSTEMS, THERMAL PROPERTIES, ENVIRONMENTAL TESTS, RELIABILITY, HERMETIC SEALS, SPACECRAFT.

Distribution Statement : APPROVED FOR PUBLIC RELEASE