Lynn Kasdorf
02-27-2008, 2:59 PM
I ran across this trick today, and tried it, and so far it seems to work very well!
If you have a DC welder, or other serious DC power supply, you can apparently burn out the cadmium dendrites or whatever you call the little growths that internally short out nicad cells.
First verify the polarity of the welder with a meter. I used my Miller 250 mig, and when set up for non-flux wire, it is positive on the gun. After I ran a couple inches of wire out, I unclamped the wire feeder. And I turned off the gas.
Now, determine the polarity of your battery pack. They are generally marked.
With goggles (clear ones are ok- I used a full face shield), hold the ground clamp onto the neg of the battery and spark the welder's positive onto the positive of the battery several times. Don't hold it there, just scrape it across until it sparks a few times. You won't be drawing huge current, although when I did it, the mig wire did glow red a couple times. But not enough to draw a welding arc. I sparked it maybe 6 times. Takes a couple seconds.
Not that I think it makes much difference, but I put my welder on max voltage and current. The impedance of the battery is such that you won't draw anywhere near the capabilities of the welder. From the wire glow, I'd guess maybe 20 amps. I gave it as much voltage as I had available. What the heck...
I did this today with a dead 9.6v battery on an old Panasonic drill. After sparking it a few times, this was enough to make the drill spin! Not nearly a full charge, but a pretty impressive immediate charge. I then put it in the charger, and after 10 minutes (not a full charge), the drill ran pretty well. I'll check on it later to see how it holds a charge.
I have a bunch of dead nicad packs that don't take a charge. I was planning on re-celling them, but this is radically easier! I'll dig out some of my dead ones soon and try doing them all, and report back. I figure it is worth a try- what have you got to loose if the cells are dead?
I have no idea if this would help out battery types other than nicad.
Don't sue me if the battery blows up, etc. Do this at your own risk. FYI
If you have a DC welder, or other serious DC power supply, you can apparently burn out the cadmium dendrites or whatever you call the little growths that internally short out nicad cells.
First verify the polarity of the welder with a meter. I used my Miller 250 mig, and when set up for non-flux wire, it is positive on the gun. After I ran a couple inches of wire out, I unclamped the wire feeder. And I turned off the gas.
Now, determine the polarity of your battery pack. They are generally marked.
With goggles (clear ones are ok- I used a full face shield), hold the ground clamp onto the neg of the battery and spark the welder's positive onto the positive of the battery several times. Don't hold it there, just scrape it across until it sparks a few times. You won't be drawing huge current, although when I did it, the mig wire did glow red a couple times. But not enough to draw a welding arc. I sparked it maybe 6 times. Takes a couple seconds.
Not that I think it makes much difference, but I put my welder on max voltage and current. The impedance of the battery is such that you won't draw anywhere near the capabilities of the welder. From the wire glow, I'd guess maybe 20 amps. I gave it as much voltage as I had available. What the heck...
I did this today with a dead 9.6v battery on an old Panasonic drill. After sparking it a few times, this was enough to make the drill spin! Not nearly a full charge, but a pretty impressive immediate charge. I then put it in the charger, and after 10 minutes (not a full charge), the drill ran pretty well. I'll check on it later to see how it holds a charge.
I have a bunch of dead nicad packs that don't take a charge. I was planning on re-celling them, but this is radically easier! I'll dig out some of my dead ones soon and try doing them all, and report back. I figure it is worth a try- what have you got to loose if the cells are dead?
I have no idea if this would help out battery types other than nicad.
Don't sue me if the battery blows up, etc. Do this at your own risk. FYI