So, whats the right charge current?
Depends. If using an unregulated charger — one that doesn’t do any detection of full charge, then one must restrict your charge current to the overcharge capacity of your cell. All NiCd cells I have seen can handle C/10 (approx. 50 mA for AA cell) indefinitely without venting. This is not to say that one won’t get voltage depression, but rather that one won’t destroy the cell(s). If one wants to get a bit more aggressive, a C/3 charge will recharge the cells in about 4 hours, and at this rate, most cells will handle a bit of overcharge without too much trouble. That is, if one catches the cells within an hour of full charge, things should be OK. No overcharge is best of course. Only with automatic means of full charge detection should one use charge currents above C/2. At this current level and above, many cells can be easily damaged by overcharging. Those that have oxygen absorbers may not vent, but will still get quite hot.
