Evaluation program for secondary spacecraft cells: Acceptance tests of Eagle-Picher 12.0 ampere-hour nickel-cadmium cells with auxiliary electrodes

An acceptance test program was conducted on 24 cells to insure that all cells put into the life cycle program were of high quality by the removal of cells found to have electrolyte leakage, internal shorts, low capacity, or inability of any cell to recover its open circuit voltage above 1.150 volts after the cell short test. The cells were rated at 12.0 ampere-hours and equipped with auxiliary electrodes. Test results were: (1) The capacity of the 24 cells ranged from 14.6 to 16.8 ah. All the cells exceeded the rated capacity on all three capacity checks. (2) One cell failed to recover to 1.150 volts after the cell short test. (3) During the overcharge tests, all cells but one failed the test at the c/10 rate after the first minute. (4) A special resistance test was conducted on the auxiliary electrodes of these cells to establish the resistance value necessary which would provide maximum signal power across the auxiliary electrode. The resistance value established was 10 ohms. (5) No electrolyte leakage was observed.