DIY mobile arc-welding set-ups?

Many would probably agree that, in the long run, it’s hard to get by on a homestead without being equipped to weld.  I’ve got oxy-acetylene for brazing, cutting, and metal bending - and a 180-amp MIG welder (runs on 240v line current) that handles most of what’s needed on my place.

I’ve become interested in having access to more a “mobile” DC arc-welding option, and intrigued by what a DIY guy (should I say ‘person’?) can build from available components & materials.

I came across this article on the Instructables website…  http://www.instructables.com/id/Golfcart--Welder

I’m confident the set-up works okay, but I do question the initial description in the article:  “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.”  Actually, that’s  slightly misleading, as the set-up is based on a golf cart, both as the means to get the unit from place to place and as the means for supplying power to the batteries and hence the impetus moving current through the stinger/ground arc circuit.  Without the cart’s recharging system, the batteries would drain down within a limited usage time.  Around where I live, acquiring even a very used golf cart would put the investment for the wherewithal pretty high.


This old article from Mother Earth News’s classic days (1980) is interesting.  The basic unit was put together from an old rotary lawnmower, an auto alternator, some pulleys and a belt, a 12v deep-cycle battery, some resistors, a diode, and wiring.  Apparently, most components were salvaged (or, as with the lawnmower, just old and out-of-service). The battery is part of the system to smooth the current when the arc is struck and when broken.  The author states that the unit yields a maximum of 50 amps of current available for welding.  The unit is shown and described here, in the article…  http://www.motherearthnews.com/diy/portable-dc-arc-welder-zmaz80ndzraw   Below is the circuitry schematic from the article.

My question & reason for posting is Anybody here know anything about building a mobile battery-based DC welding unit?

I would get one of those small 110V wire feed welder and a portable generator.  

That 12V thing looks jinkey.  If your'e doing structural welds, I wouldn't want to chance those with a homemade welder...

you are aware you can stick weld with 2 or 3 12 volt car batteries in series?  24 volts and 1/8" rod is minorly too cold.  You have to stretch the arc length right to breaking point to get a penetrating weld and because of the low voltage it is very easy to break the arc.  Your rod control needs to be nearly perfect.  Add another battery for 36 volts and move up to 5/32 rod and now you are a bit too hot.  You can practically try and bury the arc.  Push hard enough you feel the flux breaking against the steel to keep the arc as short as possible.  3/16 rod is about right for 36 V.  Basically you have an unlimited current source.  Keep the arc short and you have about 3X to 4x of the cold cranking time of the battery before you need to put a charger on your weakest battery running 5/32 and 36 volts.  So if it will crank for 15 minutes say then you probably have about 45 minutes to an hour of welding before needing to recharge the batteries.  It is really interesting to weld with because one of a welder's instinctive means of tracking how he is doing is listening to the welder hum or load up.  This is dead quiet other than crackle of the arc itself.  Are these great welds?  Most definitely NO.  But in many cases they can be adequate welds.  Have always wanted to build a chopper circuit to pull the 3 batteries voltage down to welding good with 1/8" rod.  

Quick PS #1  24V is really hard to strike the arc with.  I normally bounce strike but usually end up drag striking to get this to start
           PS #2  On nice thing about welding off batteries is how totally stable the current is.  No hesitation, great stability.  Noticably better than most welders I typically use.

Budget stick welders are so cheap these days it’s hard to piece together something cheaper.

I have done the three car batteries and jumper cables to weld farm equipment in the field to drag it home to a proper welder. That’s about all I would trust it for. Most of those Asian tik toks that just tack weld it together are using those kind of home brew welders.