Over the years I have heard hardware and electronics geeks mumbling occasionally about how nickel-cadmium rechargeable batteries could be “shocked” back to life, and like a lot of kind of similar mumblings I thought the idea was just balderdash. But last week one of the batteries on my 12volt Ridgid drill went bad, and my charger rejected it like a mother robin rejects a manhandled chick. So I went online to price new batteries and found that they were $40 apiece. Urk. I poked around on Ebay for a minute to see if the price was soft, and instead saw an offer for a guide to “Restart Dead Power Tool Batteries” for four bucks.
Resentful of these gits who try to pawn little tech “secrets” online, instead I Googled: “Revive Nicad Batteries.” “Voom!” I find a bunch of how-to’s.
The best appears to be this one on You Tube:
This fellow uses an arc welder to do the job, which seems like a bit of overkill to me. The one caveat about the video is that he does not specify how many amps he uses. If you do use an arc welder, I would keep the amps very low. But it’s academic to me, since I sold my arc-welder a few years ago. Instead I have a trusty 12 volt automotive battery charger that should do the job. I find the polarity of the terminals on the battery, throw on some goggles and insulated gloves, fire up the charger and a few sparky taps later plug the formerly dead battery into the drill and “VROOM!” Not only does it work, but the battery drives the drill as when it was new.
Then I remember that I still had the drill which had been replaced by the Ridgid–a nearly 18-year-old Skil “Warrior” (9.6 volts). It was still on my tool shelf, both rechargeable batteries long dead. “Worth a shot,” I thought. Hooked a battery up to my auto battery charger, spark, spark, spark. Plugged it into the drill and “VROOM!” It works again. I had not run this drill for at least five years. I now have two fully functional cordless power drills, each with two rechargeable batteries. I am beside myself with glee.
The science behind this is apparently fairly straightforward. Cadmium crystals, called “dendrites,” build up on the surface of the plates inside the battery and stifle the flow of current. An electrical surge apparently really does cause the crystals to be shaken loose.
We use a ton of rechargeable batteries in our house, and they seem to get weak after about six months to a year of use. I’m going to start zapping ours with the auto battery charger. I’m a little sick about the rechargeable ni-cad batteries and devices I’ve tossed over the years.
I now have two power drills. Bliss!