welding with batteries?

I've heard somewhere (here?) that it's possible to weld with car batteries (at least two in series, preferably 3?), and was wondering if this is true, and if it is, how would one go about it? Just connect all the negative poles in series, then the positive? I was in a situation this weekend where I could have made use of such a technique, that and making my own welding rod (info from one of the previous posts, wrap a coat hanger in wet newspaper), maybe I could have repaired my buddy's leaf spring on his trailer? (I know it wouldn't have lasted long, but maybe long enough to get two more loads of wood?) Thanks to all who don't flame me for my ignorance.

"One who asks a question is a fool for 5 minutes, one who doesn't ask is a fool for life." Old Chinese Proverb

-- Remove the OBVIOUS to reply.

No. Connect the positive of the first battery to the negative of the next battery. Connect its positive to the negative of the next battery. Now connect your welding leads to the negative of the first battery and the positive of the last battery. For most DC rods, the rod holder would be on the lead connected to the negative lead of the string of batteries. The positive lead would go to the ground clamp.

Note that trying to use batteries for stick welding can be hazardous. If you stick the electrode, a *huge* current will be drawn. One or more of the batteries could *explode*. To avoid that, you want a bit of resistance in the circuit to limit the current to only a couple hundred amps. Ohm's law says that would be about 36/200 = 0.18 ohm. A short length of brass strap could provide that.

Note also that a much better way to weld with batteries is to use a welding machine designed to run off of batteries. One such machine is the Readywelder (a wire feed welder). It has circuitry which would avoid drawing so much current that the batteries could explode.

Gary

I recently bought one of these Ready Wellder II (MIG) units as well as a Premier Power Welder (Stick). I bought them for field repair on my old Jeep. They both have a very good reputation with the off-road groups out here. A link to the site that sells both is:

Howdy,

You might like to visit my Yahoo website, as it has quite a lot of info on the subject of homemade arc welders. I have been using a 3 battery system for 5 years. About 2 years ago, I changed to another homemade system. The AmpTramp, is a diesel powered DC arcwelding system that can provide a steady 240 amps of welding current.

The battery powered system, helped me to build most of this 1000KG machine :) .

As another NG member has stated, you need a small amount of electrical resistance between the batteries and the load. Failure to do this, makes a mess of the welding process - and subjects the batteries to excessive abuse. I used 16 metres of mains cable as my 'resistor' and welding cable. Though it is essentially overloaded by all that current, it works famously and survives without overheating - but wastes a truckload of power. The batteries in the system, had a typical lifespan of 2 years. Not bad, as they were the cheaper sorts, as used in many cars. The golden rule - for longevity, keep 'em charged.

Anyway, please feel free to visit my Yahoo Groups website:

You should be able to find answers to, at least, some of your questions.

Best wishes,

Steve.

Steve Tee wrote: (clip) The batteries in the system, had a typical lifespan of 2 years. Not bad, as they were the cheaper sorts, as used in many cars.(clip) ^^^^^^^^^^^^^^ A good source of inexpensive batteries: Wrecking yards (the PC term is Auto dismantlers.)

Steve the sight was lacking a photi i would love to se what you have Here is some of my tinkering with home brew welders

Rather creative looking - nice job!

Martin

Thanks to all, but what I was looking for was whether I could have fixed this particular trailer using just the battery or batteries from the car, and maybe make my own electrode. (I happened to have a welding shield in the trunk.) You gave me some good information, maybe I'll just try it at home someday (with an old battery).

Howdy Wayne,

Yes, you are quite right - I need to take a few pics of the machine from a better viewpoint, so the whole thing will appear in the picture.

As yet, it is bereft of a control panel - so, when I open the rear door, I can see all the way to the front of the machine.

The site is full of photos and videos, but it is still possible that I have failed to properly show this machine in it's true glory :) .

Perhaps, you might like to suggest some of the pics you'd like to see on the site.

By the way, I like your site - you've got some interesting ideas there, that I would like to try :) . To add Mig and Tig to my machine, would be a great benefit. I'd like to be able to repair the bodywork of my old truck, she needs fixin' .

Best wishes,

Steve.

Howdy Martin,

Thanks kindly :) . This project is constantly being developed and improved.

It is quite a long way from being complete, but has already served 2700 Hrs of reliable operation. I use it for everything - including house building, windmill construction, metal working, machine construction / repairs, offsite welding, home power, farm fencing, shelter construction, and cooking feeds for my horses :) .

This, one tonne, machine is one of the most useful things I have ever built. I hope to build others, that are smaller and more portable - so I can take them to distant locations, to get the work done.

Cheers,

Steve.

Just needs a set of bulldozer treads and a seat...or 4 wheels, depending on how far you want to take it.

Hehehe, well... I have actually been using it as a tractor. I had a big tree that needed to be felled. I 'AmpTramped' it, and it didn't stand a chance :) . I have even used it to cart a trailer load of hay across the farm, chased by a host of my equine companions.

I reckon I might grab the bucket seat out of my old sporty car, and add a set of, flame proof, fluffy dice LOL :) .

Best wishes and welds,

Steve.