How to Fix NiCad Batteries Dead 18volt Craftsman drill. About 6 years old. Worked great 9 months ago.

Dead Pack Yellow light on charger indicated “soft start” or defective battery. Left on charge 48hours, yellow light remained. Only 9 volts on this pack, other pack was 2.3 volts

Using DC Car Charger Read on internet these batteries crystallize inside, causing error. Zapping with car charger (and safety glasses)

Couple Quick Zaps Tried a couple of settings, these worked fine. Held Positive on battery terminal, and struck negative like a match on other terminal

Took 5 Seconds Total The battery Positive and Negative are marked. After Zapping only 3 or 4 times, Voltage jumped up to 14 Volts.

Now It Works! Just enough juice to allow charger to work. Red light indicated “fast charge” Green light was on in 20 minutes and drill works like new.