Batteries + Jumpercables = DC Welder

[briskwinds]

"Here's the simplest welder you can make.

It's just a pair of jumper cables and a welding rod.

Oh yeah. And some batteries to power it."

http://www.instructables.com/id/Golfcart--Welder/

[tanner0441]

Hi

If you try this you will be impressed, no nasty buzzing like AC welders, just a nice hissing sound with the flux curling up nicely behind the weld pool.  I would however recomend welder cables, jump leads are not realy flexible enough.

Brian

[Madscientist267]

Interesting. A little scary, but interesting. I guess if it works, it would be ok in a pinch, but I don't know about for everything.

Thats gotta be tricky, with little control over the current flow. Maybe with several selectable 'secondaries' on the inductor to shunt with damping resistors could provide a little control... ?

I guess the only thing that bothers me a bit is the whole sticky rod thing. He says he 'couldnt make it stick if he wanted to', but imagine if it did... whew.

[wooferhound]

Here are some stories from others that have done it . . .

ttp://www.fieldlines.com/story/2003/7/27/232842/161

http://www.fieldlines.com/story/2005/4/11/03634/7918

[wooferhound]

http://www.fieldlines.com/story/2003/7/27/232842/161

[esc]

Back when I was in high school, and a friend of mine worked the graveyard shift in a gas station, he showed me how to do that.  I didn't believe him when he first described it, so he gave me a demonstration and it worked surprisingly well.

I always figured it was pretty hard on the batteries, but I could see doing it on the side of the road to repair a trailer frame or something.  I carry a couple of welding rods in my emergency supply kit.

[jacobs]

Welding from a set of batteries is not a new development. DC welders were one of the many 32 volt appliances that were sold during the pre REA days. These welders were wired directly to the 32vdc battery bank and had internal resistors built in to limit the current while welding. It's my understanding they worked very well.

[tanner0441]

Hi

Using a bank of 2V cells I have used this method several times, tapped at 32 to 48 V the batteries were the exciting current for a 240V 9.5 KW diesel generator. It works especialy well on cast iron, you do need the correct rods for cast.

Anything below 30 volts and you will not get the penetration, most AC welders use 48 or 90 V open circuit. MIG welders use 24 to 48 V OC but they rely on rectified AC giving 100 pulses a sec (UK) TIG welders use various voltages but need AC if you want to weld aluminium, DC for Stainless and iron based metals.

If you have never welded before learn on a basic AC unit where the current will remain stable not reduce as the battery discharges, and welding a tower as a learning project which will have twisting and bending forces on it not to mention vibration, is a recipe for disaster..

Brian

[aussiebushman]

Have just completed a trolley mounted DC welder using a 5.5 Hp motor and 100A alternator with the regulator removed.  All seems OK but I only get a pathetic little speark and the voltmeter shows only 6V

The circuit was almost identical to the "120A Chrysler alt welder" article except that I added a shunt to measure the DC amps due to the lack of a 100 A ammeter. - see PDF file with schematic and picture of the unit on the trolley

If there are any experts on the forum who can explain what I am doing wrong and how to fix it I'll be most grateful.

Cheers

Alan