Just Fixed a Battery with a Welder!

[Iplayfarmer]

This was the coolest thing. If I was a betting man I'd have lost a lot of money because I'd have bet 10:1 odds against this working.

My brother came over today with his two dead batteries from an 18V cordless drill, and wanted to use my welder for a minute. He'd seen some YouTube video about a guy re-furbishing a battery with a DC welder. I cautioned him that my welder is AC, and it doesn't go down very low. He said that he didn't have much to lose since neither battery was working. I hooked up the welder, but I made him go out in the driveway anticipating a spectacular explosion.

We clamped some welding rods (bare Ox/Ac type welding rods) to the positive and negative terminals of the battery using a bicycle inner tube as insulation between the rods and the clamps. We hooked the welder ground to the battery negative and then touched the battery positive lead a few times with another bare rod that we'd clamped in the electrode holder. Other than the typical striking arc, there was nothing spectacular.

He put the battery on a quick charge, and low and behold it charged great and ran the drill just like it should.

We fried the second battery when he stuck the rod to the battery positive for a few seconds.

Now I'm wondering what other batteries this would work on. I have three old lawn mower batteries that I'd like to refurbish.

 

[BobRip]

I have seen this work on Nickel Cadmium batteries like that used in the drill. The time I tried it by dumping a charged capacitor into a battery cell it only worked for a little while. The Nickel Cadmium batteries develop tiny short circuits inside some cells. The high current is supposed to burn the short open. Will it work on a lead acid? I don't know.

 

[Tig]

It's not a very safe thing to do since NiCads are toxic. I used to rejuvenate NiCads. I would place the battery in a "bomb box" and monitor the rejuvenation with a current meter. I have not done this in the past 10 years because I figure that sooner or later, one will explode and contaminate my shop.
I am very certain that the technique I used would detonate a lead acid battery.

 

[pat32rf]

If you open up the basttery packs you will find that they are made up of multiple 1.5v cells. Quite often one will be dead, the others OK. I have opened up a couple of batteries and come up with enough good cells to make one good battery.
I've also made up dummy batteries that have been connected to small recargable 12v power packs.
Sometimes just completely draining the battery (slowly) and recharging it will work.

 

[Soundguy]

A long time ago I had a 'whisker trimmer' that generally helped nicads that were getting bad 'memory' effect.

Same principle.. high(er) voltage.. etc. burn them little shorts out.. but not enough to damage the cell.

havn't use done in years.. decades....

soundguy

 

[Jimbrown]

You do not need to use a welder. Most times any auto type battery charger will work if it is gonna work. All you are doing is getting the one cell that has dropped voltage to take a temporary charge so the auto sensing charger will cahrge the old battery. It usally only works once or twice.

 

[actionaj]

The automotive charger sounds a lot safer than a welder. I would think using a welder would have a greater chance of an explosion. I am going to have to check in to this it would be nice to get a little more life out of expensive battery.

 

[bg71361]

Here is the youtube link;

YouTube - Instructables TV Vol. 1

 

[BobRip]

Here is the youtube link;

YouTube - Instructables TV Vol. 1

Has anybody had this work for a long time after the repair? I have tried this a little years ago and they batteries did not seem to last more that a few months.

 

[Murray B]

Has anybody had this work for a long time after the repair?

Nope, as I understand it nickel dendrites grow across the cell and zapping them just opens up a small gap. It usually does not take long for it to grow back. What might help is completely discharging the cell, not the battery, to zero volts and then recharging it at the C/10 rate until the temperature rises.

Most of the time I just replace the cell or all the cells in the pack. There are a few companies that will spot weld up custom packs for a reasonable price or you can buy cells with solder tabs and make your own.