wanttaja@ssc-vax.UUCP (Ronald J Wanttaja) (12/08/84)
Pardon me, I'm getting into this battery life discussion rather late, but has anyone mentioned reconditioning NiCd batteries? NiCds have a memory, if you discharge them only to a certain point every time, they remember that point. Should you ever have a need for longer life, the batteries may discharge to that memory point, then say "I quit" and go to zero rapidly. The solution is to recondition the batteries: discharge them completely at a moderate rate (leave the calculator on with all "8"s on the display, for instance), then recharge. Repeat several times. In the Air Force, we would perform up to three reconditioning cycles on our spacecraft batteries before the eclipse season. We didn't take the batteries down to zero, (delivery costs being so high) we just took them from 31V down to 22V or so. We would recondition the batteries for our TI-59 at the same time. Another problem which might occur with NiCds is shorted cells, which can be blown out using relatively low voltage, high current pulses. If the battery refuses to charge up fully (1.2 V or so), line up the highest capacitance you can, charge it up to 15 volts or so, then discharge it through the dead cell (LIFE! Give my Creation... LIFE!). An electronics supply store here sells surplus LARGE capacitors for about $15 a Farad- I've got two caps totalling 1/4 Farad, in parallel. If that doesn't work, crank the charge voltage 5 V at a time. By the way, hook up the caps to the dead cell as if you were charging it: plus to plus, minus to minus. Check the cell with a voltmeter after every jolt- if it's working, the voltage should start coming up. You may have to jolt it several times until the short is completely cleared (battery voltage to 1.2v). Note that this should only be performed to a single dead cell... if you have a battery pack in which one of the batteries is bad, you will have to isolate that battery. Try sticking needles through the plastic to make contact with the bad battery's poles. Ron Wanttaja (ssc-vax!wanttaja) "Batteries to power...turbines to speed..."
fmc@pyuxqq.UUCP (fmc) (12/17/84)
I Isn't there a danger of the battery exploding if you follow these procedures?