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[Rods2]

I've got a couple of decent rechargeable drills on which the batteries have got very tired. I heard that by passing a high DC voltage of about 30v through them for a short period it breaks down the crystalline structure that shorts them out and stops them from holding a charge.

In the demo he uses a welder, which I've got, so, has anybody tried this and did it work successfully?

http://www.instructables.com/id/Revive-Nicad-Batteries-by-Zapping-with-a-Welder/

[zirk]

Never tried a welder, would have though too high a voltage tbh, in the old days Ive tried sparking some AA type (1.2v) across a 12 v Car before now with results, so guessing if your drill battery is either 12, 18 or 24 volt then you would need something in range of 120,180 and 240 v DC source, which sounds all a bit dangerous to me, think I would probably brake the battery casing and do each cell in turn off 12 volts or just replace with new cells.

[STMO123]

Tell your wife it's perfectly safe and get her to try it. Stand well back, of course.

[martin42]

Make sure wife is insured 1st tho 

[r1]

Make sure wife is insured 1st tho 

and dont hold her hand!

[Martian]

Never tried a welder, would have though too high a voltage tbh, in the old days Ive tried sparking some AA type (1.2v) across a 12 v Car before now with results, so guessing if your drill battery is either 12, 18 or 24 volt then you would need something in range of 120,180 and 240 v DC source, which sounds all a bit dangerous to me, think I would probably brake the battery casing and do each cell in turn off 12 volts or just replace with new cells.

It's not volts that are needed, it's amps.
Those type of voltages applied to a cordless drill battery will definitely result in a fairly impressive catastrophic failure of the battery, and most likely the individual holding the wires as well.

[Kevin Wood]

Never tried a welder, would have though too high a voltage tbh, in the old days Ive tried sparking some AA type (1.2v) across a 12 v Car before now with results, so guessing if your drill battery is either 12, 18 or 24 volt then you would need something in range of 120,180 and 240 v DC source, which sounds all a bit dangerous to me, think I would probably brake the battery casing and do each cell in turn off 12 volts or just replace with new cells.

It's not volts that are needed, it's amps.
Those type of voltages applied to a cordless drill battery will definitely result in a fairly impressive catastrophic failure of the battery, and most likely the individual holding the wires as well.

Indeed. No need for much more than the normal terminal voltage of the battery, as if it's developed tin whiskers it'll be essentially shorted. IME, the revival is not long-lived enough to make it worthwhile, generally. Get some tagged cells off Ebay and replace them.