Instructables shows us how to “zap tired old Nicad tool batteries back to life with a mig welder.” Video after the jump.
Nicad batteries often die in such a way that they won’t take a charge and have zero voltage. This usually means they’re shorted out by crystal dendrite growth. Here’s a method of bringing them back to life by zapping those shorted crystal dendrites away with too much current and/or voltage. We’ll use a welder as a power source