Welding with car batteries?

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I have read some about this and would like to hear first hand from any one who has done it before.
Reply:why? lol...."watch this!"
Reply:ive tried it just fooling around two batteries in sieries 24v 7016 or 6010 1/8" it worked but had a real hard time starting a arc good luck    use long leads keep the battries far from sparks
Reply:There is a company called ready welder.  They make a spool gun that uses deep cycle batteries.  check out their web site. http://www.premierpowerwelder.com/re...readyweld.html
Reply:Short answer...yes, with the right equipment, you can weld just fine.I have used the readywelder and a two batteries to weld a bunch of aluminum bleachers...well, argon also, but that goes without saying, right?Two batteries lasted about an hour, maybe an hour and a half of maybe 20%-30% duty (just a guess).  The welder was great.  It has a cheap gas valve built in that is pretty wasteful, but it worked like it was claimed to even outdoors with gas.  After I was done, I had to put the fluxcore roll that was in the welder to begin with back in.  I tried it also on some scrap from the old steel bleachers.  The beads were pretty good, but the batteries were running low, so I dont know if it would have been a whole lot better at full charge.Smithboy...if it ain't broke, you ain't tryin'.
Reply:I've got a Rediwelder,+ Love It.......My 1st mig welder was a Snap-On/ Century Battery powered portable, that used the Big rolls of wire,+ Pushed it the length of the whip........I set it up for Aluminum, with a couple of big deep- cycle batteries,+ a dedicated 24V battery charger........It got the Job Done,............I built a Rigid Bimini Top for my boat with it......Since I got the Rediwelder the Snap-On resides under the bench somewhere,...... No more hung wire,+ refeeding it..........Pull the Trigger,+ Weld................I'm thinking about getting another 1 to set up for Steel,..........
Reply:I spend lots of time 4-wheeling, and we have to be ready to fix just about anything on the trail.  There are plenty of onboard welders out there, but they're too expensive and complicated for me.  I run dual batteries in my rigs for winching anyway, so I decided to try battery welding a few years back.  All you need is an electrode holder, ground clamp, and leads. I use military style battery terminals to make it easy to switch between parallel hookup for normal running and series for welding.  I found that 1/8" 6013 works best for me.  Of course there is no control of amperage, but by varying your technique you can weld anything from exhaust pipe to leaf springs. We have repaired broken driveshafts, springs, etc. on the trail and it works great. I wouldn't do this at home, but on the trail you do what you gotta do. Attached Images
Reply:George,what amps would you estimate you are welding at?Smithboy...if it ain't broke, you ain't tryin'.
Reply:Originally Posted by smithboyGeorge,what amps would you estimate you are welding at?
Reply:I have been tempted to set up one of these jobs on my dad's tractor (a 24v system), but just havent gotten around to the details on the connectors.  After using the readywelder, I was also tempted to get one of those, but....$400+ has kept me just tempted, and I like stick better anyway.  I was thinking about using the alternator-to-welder trick, but havent run across a good cheap 100+ amp alternator that I could use for that.  I like simple also.Smithboy...if it ain't broke, you ain't tryin'.
Reply:Man, you guys are like Mcguyver. Remember that episode where he welded the boat motor spark plug back together and got away just in a knick of time before the bad guys got him? Besides hooking up the battery he wrapped one of the leads around and around a vise. What was that all about, dropping the amperage maybe? Maybe George could do that on the trail. Also speaking of welding with alternators, has anybody welded with one of those Zena welders? They sound like pretty much like the same thing from their website.Last edited by 12,000 Doors; 11-06-2005 at 04:10 PM.
Reply:Never used a zena, but I have an old highschool buddy that rebuilds car alternators and starters, and he showed me how to use an old ford alternator for exactly the same thing.  He used to have a unidentified v-8 set up on a trailer as a generator/compressor/welder/grilled cheese sandwich maker.  Talk about McGuyver...this guy was a nut, but he was always coming up with stuff that you wished you had thought of and making a single-purpose thing into a swiss-army-knife-of-a-thing.  Only 4 cylinders were used to run, the other 4 were used to compress air...at least I think they were.  He had a bank of three alternators wired together as a dc welder and an old generator head on the other side of the motor pumping 120-240 ac.  At the time I didnt pay much attention to how he accomplished this, but now I wish I had.Smithboy...if it ain't broke, you ain't tryin'.
Reply:I sure would like to hear from Anybody that's got a Zena............I'm close to breaking down,+ Buying 1.............If it'll do like he told me on the phone,+ what I've read,....... It Sounds like Money Well Spent.......I'm lead to believe that I'll be able to run this off my Pickup,....Running Their Equipment for welding with Stick,......Or,.. Just plug in my Redi-welder,......Or,... Plug in the Jumper Cable,+ Spin about Any motor over in about Any temperature..............
Reply:Ah MacGuyver, the most dangerous arts and crafts guy on television. Did you catch the episode where he made a nuclear bomb out of a paper clip and some Nyquil? Originally Posted by 12,000 DoorsMan, you guys are like Mcguyver. Remember that episode where he welded the boat motor spark plug back together and got away just in a knick of time before the bad guys got him? Besides hooking up the battery he wrapped one of the leads around and around a vise. What was that all about, dropping the amperage maybe? Maybe George could do that on the trail. Also speaking of welding with alternators, has anybody welded with one of those Zena welders? They sound like pretty much like the same thing from their website.
Reply:I have a Zena welder.  It works great.  Extremely convient.  I got mine off ebay for $450.  It was a promotional thing, I guess.  However, once you get it you will need to fabricate bracket, Possibly purchase an additional pulley for your existing alterantor, Idle control is convient.  While it comes with 20 foot cables you might want to purchase longer cables at the time of purchase. You have an additional wire connecting to the electrode to the welder (2 welding cable + control wire), since all of the controls are in the handle.  I fabricated some 100 foot extension with quick connects, the parts are available at a electrical supply house.  I don't think I saved any money fabricating my own extension.I think you need additonal accessories inorder to hook up the ready welder.It sure beat carrying a engine driven welder. It is 100 % duty cycle. 150 amps dc. Weld and cuts well and easy to control amps.  My only concern was the electrode being so complex.  However, I keep the original 20 foot leads in my truck and the extensions on my trailer.  I have never had to use my extensions since I can drive my truck up to within 20 feet of most jobs.  I have about $700 plus lead extensions in the set up.
Reply:Has anyone used the SB Anderson quick disconnect hookups like they use on forklifts?  They are rated for 350 amps.  That ought to be enough.  What about increasing the voltage?  I have a battery pack that is 500 amp hour (At the 5 - 8 hour rate) and is 48 Volts.  I wonder how that would weld?  It weighs 923 Kg., so isn't too portable, but I could use 6 volt golf cart batteries in series (220 Amp hours at the 20 hour rate deep cycle) to get the desired voltage.  How much voltage is enough and how much is too much?  Any ideas are appreciated and what welding rod as voltage goes up.  I have no idea how much amperage the things could manage, but it might be LOTS!HH 180 HF O/AHF Plastic Welder HF 14" CutoffHF 4 1/2" GrinderMiller big window elite Dewalt 18 Volt Cordless 4 1/2" GrinderGNB 48 volt 500 AH battery (At 5 - 8 hour rate)Mostly Things that start with H
Reply:http://webapp1.cronatronwelding.com/...temNum=CW03191
Reply:fixer67 asked about welding with car batteries and wanted to hear first hand from any one who has done it before.jwweld said he tried it just fooling around two batteries in series 24v 7016 or 6010 1/8" it worked but had a real hard time starting a arc good luck use long leads keep the batteries far from sparks.  I tried this on the weekend.  First with one car battery; with only 12 volts I could drag a line of light little sparks - but no arc.  Then, I tried again with two car batteries in series (24 volts) - success after a fashion.I tried 2 battery welding with two different rods:5/64 inch Lincoln 6013It was easy to start the arc with a new rod.  But if the arc went out, I discovered that I could not restart the arc, just like jwweld said ....until I scraped the rod tip along the concrete floor to remove the flux sleeve off the rod tip and expose the rod metal again.  The arc went out so many times this became a pain, so I switched to another rod type.3/32 inch (no name) 6011Because this rod does not form the same hard flux sleeve around the rod tip, I had no trouble restarting the arc at any time.The big problem was no current control - just as George Womack said in his response, "Of course there is no control of amperage - but by varying your technique you can weld anything from exhaust pipe to leaf springs."In my case, my technique or lack thereof could not compensate for the availability of so much current.a) I found that I had to weld in short spurts, making and breaking the arc else I laid down too much metal - too fast (maybe I have to move faster).b) Also, each restart of the arc tended to throw globes of molten metal about several feet in all directions.c) I had to be very careful on restarts not to stick the rod - spectacular!I normally use a small 117 volt AC welder with about 85 amps max output.  When I had a rod stick, I heard a hum in the welder and the tip of my rod turned red - and sometimes a little fire took place at the very tip.Ha - Ha, with the car batteries, it was a whole different story!  Get the rod stuck and within a second or so the whole rod is on fire and cherry red from end to end!  That's the end of the rod since you have boiled out all the special flux ingredients.However, having said all these nasty things, I must say that the welds made by the two battery system were not bad.So, if this battery welding system could be equipped with some form of current limiter, then yes it works OK.Ideally, I think that using three batteries to obtain 36 volts would make for easier arc starting for hard-sleeve-tipped rods like 6013, 7014 and 7018.Current control is needed: maybe a carbon-pile (used by auto shops to test batteries under load) to limit the current to reasonable levels.With those two items (higher voltage and lower controllable current) I would say that a car battery system could work pretty weld for stick welding.Rick V.
Reply:Pretty cool little piece of equipment and quite portable!John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:24 Volt - 2 Battery SystemTest of car-starter-motor solenoid system.Test #1In my previous post #18, (call that Test #1) I had used two mismatched batteries: one a marine starting battery (~80 amp-hour) and the other a small car starting battery (~60 amp-hour).  I hooked them in series using one 8 foot length of #8 gauge copper wire from a cheap jumper cable.  I used a 20 foot long, #1 gauge, jumper cable - clamped to the negative terminal at one end and clamped to the work as ground at the other end.   I also used a 20 foot long, #1 gauge, jumper cable - clamped to the positive terminal at one end and clamped the rod at the other end.Test #2This time I thought would be better!  Call this test #2.  I used six matched marine deep cycle batteries of 100 amp-hours each.  Three batteries were connected in parallel using copper bars as conductors.  This was repeated for the second bank of three batteries.  I hooked the two banks in series using a 4 foot length of #4 jumper cable.  Like before, I used a 20 foot long, #1 gauge, jumper cable - clamped to the negative terminal at one end and clamped to the work at the other end.  However, for safety sake, I wanted to be able to quickly stop the current flow in case I stuck a rod.  So, this time I passed the welding current through a starter-motor-solenoid/relay controlled by a trigger on the rod holder.  Rather than come straight off the positive terminal using a 20 foot long, #1 gauge jumper cable to the rod as before, I passed the current weld through a starter-motor-solenoid/relay.  Thus, I came off the positive terminal with a 3 foot length of #4 gauge copper booster cable to the solenoid/relay.  I left the solenoid/relay with a 4 foot length of #4 copper booster cable - that connected to the 20 foot long, #1 gauge, jumper cable.  That #1 gauge cable was clamped to a 5 foot length of #4 booster cable going into a screw-type (Bernhard) rod holder.Here is what I observed.5/64 inch Lincoln 6013Test #1: It was easy to start the arc with a new rod.  But if the arc went out, I discovered that I could not restart the arc, until I scraped the rod tip along the concrete floor to remove the flux sleeve off the rod tip and expose the rodmetal again. The arc went out so many times this became a real pain.3/32 inch Forney 6013Test #2: I could not really get an arc started - just brief flashes of arc.  I had to do a lot of rod scraping on the floor - as with Test #1.3/32 inch (no name rod from Princess Auto) 6011Test #1: Because this rod does not form the same hard flux sleeve around the rod tip, I had no trouble restarting the arc at any time.Test #2: I never really got an 'arc' going.  I welded almost like a wire-feed welder - short-circuit welding: jam the rod into the joint and get a short-circuit melt off, followed by brief arc - then repeat jam/arc, jam/arc, jam/arc.  I could not get a continuous arc going.In Test #1, I found that I had to weld in short spurts, making and breaking the arc else I laid down too much metal - too fast.  In Test #2, I had no arc and could only weld by short-circuit jam/arc method.In both Test #1 and #2, each restart of the arc tended to throw globes of molten metal about several feet in all directions.In Test #1, I had to be very careful on restarts not to stick the rod - within a second or so the whole rod was on fire and cherry red from end to end!  In Test #2, I could use a trigger on the rod holder to trip the solenoid/relay off - stopping the welding current.  However, even when the trigger was held down, I did not get the flaming rods observed in Test #1.  NOTE:  I suspect that I had so much more current available (24 volts at 300 amp-hour instead of 24 volts at 60 amp-hour) that I just melted off the rod end of any short circuit!In Test #2, as well as trying 3/32 inch 6011 and 6013, I also tried 3/32 inch rods in 7018 and 7014; they behaved like 6013 forming a sleeve around the metal that made maintaining the arc difficult.  I did get some short 1 inch runs with 7018 that were excellent but it was very difficult to maintain the arc.Because of the problems in Test #2, I rechecked all the connections and improved on some of the connections.  A repeat test with 6011 was better - there was obviously more current at the rod as restarts caused more flash and a larger shower of globes of molten metal throw about... but I still could not maintain an arc.36 Volt - 3 Battery SystemTest #3I used three matched marine deep cycle batteries of 100 amp-hours each.  I hooked the batteries in series using 4 foot lengths of #4 jumper cable.  I used 20 foot long, #1 gauge jumper cables from the battery terminals to the work area, the negative end clamped to the work piece, the positive end to a rod holder.With 36 volts, I could easily start and maintain an arc with all the previous rods! Yeah!! However, the current was rather high (I had to turn up my auto-darkening helmet from #9 to #12!); the high current caused problems.Here is what I observed welding T filets with 1/4 inch thick mild-steel stock.  3/32 Lincoln 7018 ACVery forceful arc, I had trouble with maintaining distance: too close and I rapidly melted the base metal (undercut) and if I backed off too far I created porosity, a little farther and the arc went out.  I could not restart the arc without scraping the end of the rod across the concrete floor.  In the end most the weld looked full of tiny holes.3/32 inch (no name rod from Princess Auto) 6011The arc was strong.  There was no trouble starting, maintaining or restarting the arc.  The problem was too much heat input – you had to rush and this was not good.5/64 inch Lincoln 6013I figured I would try a smaller diameter rod to see if that could tame the higher current.  NO!  The arc was so forceful and focused, it just zipped a hole (looked ~1/8 inch in diameter) right through the 1/4 inch thick vertical plate – in the blink of an eye!1/8 inch Forney 6013I figured if the smaller 5/64 inch 6013 wanted to poke holes through 1/4 inch plate, I would move up to a larger 1/8 diameter rod – hoping for a softer, wider arc.  Opps!  Wow – a lot of heat input, causing major undercut – like half the wall thickness of the 1/4 inch thick plate just flowing away - caving in!===//===So, where does this leave us?24 volts – not enough to start and maintain an arc.  One has to short-circuit weld = jab/arc.  When it does weld, it is good.  Real pain in the butt though.36 volts – easy to start and to maintain an arc.  Big problem is too much current – at least for welding 1/4 inch plates.  (It might great for 1/2 inch plates.)  If one could add some form of solid-state controller for amperage, this could be a decent welding system.So, anyone got a 30 volt battery?  That seems to be what is needed.What next – that is easy and cheap to try?My next step: use the 36 volt system but add in a resistor (big open coil of 0.035 MIG wire) to drop about 6 volts – placing say 30 volts on the weld while flowing about 100 amps.Stay tuned…Rick V.
Reply:Why not just use a dimmer switch to vary the voltage/amps?
Reply:Originally Posted by gimpyrobbWhy not just use a dimmer switch to vary the voltage/amps?
Reply:If you could come up with a < 1 Ohm, high-wattage resistor you might get some goodresults.For example:V=IR, so I=V/R and V/I=R (Ohm's law). If V=36, and you want 72A forwelding thinner material, then 36/72=0.5 OhmP(in Watts)=VA, so 36*72=2592W,so with a 2.5KW, 1/2 Ohm resistor you could tame your 3 batterysetup. I don't know, put perhaps a calrod element for an oven ora heating coil for a hot plate or electric range would do the trick.I'm curious to hear more of your experiments.
Reply:Originally Posted by gimpyrobbWhy not just use a dimmer switch to vary the voltage/amps?
Reply:Well I don't know. I have seen people put them in systems like this: http://www.huv.com/jon/jeep/Welder/assembly.html  and have lots of success. Just trying to help.Originally Posted by Rick V24 Volt - 2 Battery System...So, anyone got a 30 volt battery?  That seems to be what is needed.What next – that is easy and cheap to try?My next step: use the 36 volt system but add in a resistor (big open coil of 0.035 MIG wire) to drop about 6 volts – placing say 30 volts on the weld while flowing about 100 amps.Stay tuned…Rick V.
Reply:as i read this thread..all i can say is dont do that near me..  ...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:I'm with the Zapster on this one.  Lead acid batteries don't take kindlyto abuse and generate hydrogen and oxygen in a perfectly explosive mixture.Sulfuric (Sulphuric to our Canadian friends and my fellow Brits) acid is highly corrosive to just about everything including people!  Come on and run away run away.My angle grinder is my best friend!
Reply:What size and form of Resistor?To maintain an arc, we know 24 volts is not sufficient and 36 volts results in a good arc but too high a welding current. Let’s assume that 30 volts on the rod will maintain an arc.Let’s assume at 120 amps or so would be a good welding current.In my experience, with about a 100 amp load , a fully charged 100 amp-hour deep cycle marine battery will operate at about 12 volts.  So with three batteries in series, we are starting with 36 volts from the batteries.This means we want a resistor that will leave 30 volts on the rod, the resistor dropping the other 6 volts and also limiting the current to 120 amps.R=V/R = 6volt/120amps = 0.05 ohmsPower in the resistor = IxIxR = 120 x 120 x 0.05 = 720 watts.Note: If you stick (short circuit) a welding rod, the resistor will quickly burn up as the power dissipated will rise enormously.  Forgetting about any cable and internal battery resistance:Amps = V/R = 36volts/0.05ohms = 720 amps,Power = IxIxR = 720x720x0.05 = 25,920 watts!!!Still, you are safe!  You only have 100 amps or so unless you really stick a rod good, then the resistor blows shutting down the current.Anyway, with my system, I use a trigger switch on my welding rod holder to turn the welding current on/off through a starter-motor solenoid/relay.Hey not everyone has $600 bucks for a new 140 amp DC welder and the battery approach may offer an economical way to gain that capability and more.  For off-roaders, battery welding is well known and the subject of a few good articles that may be found by searching the Internet.  What is missing is some quantitative data on how various welding rods perform using different battery systems.  I believe that a few experiments are in order.Back to the Resistor...I looked at what materials I could make the resistor out of.  Folks, I looked into various diameters of copper wire, aluminum wire, nichrome wire and steel wire.  After pages of calculations, the best deal seemed to be to use 0.035 steel MIG wire.  On sale, I can buy a 2 lb roll for $5.How many feet of 0.035 inch diameter wire in a 2 lb spool?Density conversion factor: 1 gm/cubic cm = 0.03612 lbs/cubic inch  Density of steel = 7 gm/cubic cm or  7 x 0.03612 = 0.2528 lbs/cubic inch2 lbs of steel wire has a volume of 2 lbs / 0.2528 lbs/cubic inch = 7.91 cubic inches.Wire of 0.035 inch diameter (D) has a cross-sectional area of = pi/4 x DxD = 3.14156/4 x 0.035 x 0.035 = 0.000962113 square inches.Wire Volume = Wire Length x Wire Area.Wire Length = Volume/Area = 7.91 / 0.0009621 = 8,221.7 inches or 685 feet.I measured the resistance of my 0.035 MIG wire by measuring the voltage drop across a fixed length of wire while passing 5, 10 and 15 amps of current through 2 feet of wire.  5 amps: R=0.09   ohms per foot  (no effect)10 amps: R=0.10   ohms per foot  (Wire is hot to touch, resistance rose 1.1X)15 amps: R=0.145 ohms per foot  (Wire is very hot to touch, resistance rose 1.61X)20 amps: R=0.22   ohms per foot  (Wire is red hot, discolors/wilts, resistance rose 2.44X)So, best approach is to limit the current under normal operation to say 6 amps.  Should the amperage move up into the 20 amp range, the resistance will change a factor of 2.44 and act to limit the current somewhat.For welding, we need a resistance of 0.05 ohms.  At 6 amps, the resistance of the 0.035 inch diameter MIG wire is R=0.09 ohms/foot.Wire length for R=0.05 ohms is = 0.05 ohms / 0.09 ohms/foot = 0.555 feet or 6.66 inches.Remember: We don’t want to exceed 6 amps in the wire.  But here we would be passing 120 amps through only 6 inches of wire = Poof . Vaporized Wire!What we have to do is maintain the same resistance but use more wires in parallel to limit the current to 6 amps per wire.  If we double the length of the wire, we double the resistance.  If we operate two wire in parallel, we half the overall resistance.  So, we can maintain R=0.05 ohms by using two parallel wires of double length - 2 x 6.66 = 13.3 inches.  Now we have two wires, each carrying 60 amps – still way more than our 6 amp limit.What we really need is 120 amps divided among a number of wires, each carrying 6 amps.  Thus we need 120 / 6 = 20 wires is parallel.  Each wire must also be 20 times as long as 6.66 inches.  So, we need 20 parallel wires of 20 x 6.66 = 133 inches or 11.1 feet.I have a piece of 4 x 4 foot peg board (1/4 inch thick Masonite with 1/4 inch holes every inch).  With 1/2 inch copper pipe running up two opposite edges of the board, I could feed the current into the left-side copper pipe and pick it up off the right-side copper pipe.  20 parallel wires of length 11 feet would run between the copper pipes in a Zig-Zag pattern, wire spacing about 3/4 inches.Zig-Zag?  Each wire could run almost 4 feet from the left side edge copper pipe to the right-side edge, then return back almost 4 feet to the left-side edge, then run back another almost 4 ft to connect to the copper pipe on the right-side edge.  The length of each Zig-Zag wire would be about 11 feet.  We end up with a total of 222 feet of 0.035 steel wire spread over a 4 foot by 4 foot board.This is our 0.05 ohm, 720 watt resistor – that can briefly handle up to about 6,000 watts.I’ll report back once I build this monster resistor and give it a try!(Ya-ya, I know it would be smaller if I submerged it in water – but gotta start easy!)Rick V
Reply:I found this on the Internet some time ago:  http://www.vintageprojects.com/metal...rc-welder.htmlI have not build this item, but I will try in the future.  Hope this works or gives you and idea for something better.
Reply:That old article is neat!  But I wonder how old the article is - the illustrations look like 1950's.  Back then, it may have been easy to find and cheap to buy war surplus aircraft generators of 24 volt 200 amps; today I have my doubts.On the other hand, for sale on the web are car alternators modified to be welders with almost the same ratings - so maybe it is easier.I have another project on the go that uses a 6 horse power B&S engine to drive a Delco Remy alternator out of an old Pontiac Bonneville.  This produces 140 amps at 15 volts and I use it to charge my battery bank.  However, in future I will be looking at tweeking the voltage up to 30 volts or so for welding - but that is a future project.Thanks for post - it sure is great to see the way fellows built their own gear back in the old days.Rick V
Reply:I've always wanted a large heater for my garage. Thanks for doing the math and laying out the plans. Thormold, That article reminds me of my first homemade welder. I was 11 then, I took a 100A Delco alternator and stripped the regulator and rectifiers out and used a briggs & stratton 11 Hp motor to spin it. It worked okay for about 5 minutes then the belt burned up, after a few belts the alternator burned up.
Reply:If you had ever had a battery explode in your face (like me), you would never ever consider doing this. This was many years ago, and still I cringe and lean and turn my head anytime I have to connect anything to a battery. It is no fun at all to be covered in acid and have shards of plastic (covered with acid) buried in your skin, especially when you are 10 miles from nowhere on top of a mountain in Georgia in july.
Reply:Hey Joe H...If you had ever had a battery explode in your face (like me), you would never ever consider doing this.
Reply:2 BatteriesI tried using 2 batteries and 24 volts again but I added in a home-made arc stabilizer:Clamped 3 short jumper cables together to get ~17 feet of ~#8 gauge copper wire and wrapped that around 12 strips of 1/4 inch thick x 1.5 inch x 16 long steel bar stock.This iron-core coil helped a bit – didn’t throw so much molten metal on the arc strike and the arc seemed a mite more stable.  On the downside, I had less current available (likely resistance in the two additional connections and the #8 wire) and stuck a rod a few times.3 BatteriesRecall back in post #29, in order to use 3 batteries at 36 volts, I wanted a resistor of 0.05 ohms that would limit the welding current to 120 amps?Using 0.035 solid steel MIG wire, this meant 20 parallel wires, each of 11 foot length.I got to thinking; maybe I could combine the needed resistor with an arc stabilizer - by forming the resistor wire into a coil.Calculations showed that I could achieve 0.05 ohms in one steel wire of diameter 5/16 inch and length of ~43 feet.  I can buy a 50 foot length of 5/16 inch galvanized steel cable for about $20.  I could wind this about a 4 to 6 inch diameter thick cardboard tube – spacing the adjacent turns evenly apart using another wire – that I would unwind when finished.  Thus my resistor would be in the shape of a coil of evenly spaced turns – that I could tap into at various places.  I could insert into the cardboard pieces of steel stock to increase the inductance of the coil. Note: To do the same thing with 0.035 MIG wire would require 80 parallel stands to achieve the same cross-sectional area as the 5/16 inch cable.  To achieve the required 0.05 ohm resistance, each 0.035 wire would need to be 44 feet long.  This gives a total wire length of ~3,555 feet – a mite much to handle (as anyone who has ever had a coil of MIG wire unravel will attest).Anyway, I should have the required 5/16 cable later today… then we shall see.Only one thing worries me…Once I limit the normal welding current to 120 amps, the possibility of sticking a rod on initial arc strike may be higher.  If that happens, I will have to be quick to trigger the solenoid/relay off, shutting off the welding current – else I burn up the resistor/coil.  However, the back voltage produced by the new coil may create an arc across the separating contacts inside the solenoid/relay… possibly welding the contacts together.  If that happens – well bye-bye resistor/coil.  Rick V
Reply:Originally Posted by triffid_98Ah MacGuyver, the most dangerous arts and crafts guy on television. Did you catch the episode where he made a nuclear bomb out of a paper clip and some Nyquil?
Reply:Originally Posted by Rick V2 BatteriesOnly one thing worries me…Once I limit the normal welding current to 120 amps, the possibility of sticking a rod on initial arc strike may be higher.  If that happens, I will have to be quick to trigger the solenoid/relay off, shutting off the welding current – else I burn up the resistor/coil.  However, the back voltage produced by the new coil may create an arc across the separating contacts inside the solenoid/relay… possibly welding the contacts together.  If that happens – well bye-bye resistor/coil.  Rick V
Reply:Ok folks, the results are in…Resistor/Coil (Arc Stabilizer)I purchased 50 feet of 5/16-inch diameter galvanized steel cable.  I wound the steel cable around the outside of a deep plastic bucket of average 11-inch diameter (bottom was about 10.5 inches widening to about 11.5 inches near the top).  This gave about 16.5 turns around the bucket.  To keep the turns of un-insulated steel cable from touching each other, I wound 5/16 inch yellow plastic rope between the turns of steel cable.  This also gave me a nice even spacing between the turns.  The length of the coil ended up as 11 inches.I passed currents of 5, 10, 15, 20 and 25 amps DC through the coil while measuring the voltage drop across the coil.  The resistance was constant at 0.06 ohms.  Recall I was aiming for 0.05 ohms with 44 feet, so I was only off by about 5%.Batteries/Coil/Rod-holderI used the three 12-volt deep-cycle marine batteries as before with a rating of 100 amp-hour at a 20-hour rate.  I joined the three batteries in series (36 volts) as before using 5-foot lengths of #4 gauge cable with heavy-duty (300 amp) spring-loaded battery clamps.  I used 20 feet of #1 gauge booster cable from the negative battery terminal to the work piece.  I used 20 feet of #1 gauge booster cable from the positive battery terminal to end of the coil.  I used a 5-foot length of #4 cable from the other end of the coil to the rod holder.   Voltage/Amperage MonitorI connected a digital voltmeter across the coil, connected with the booster cable clamps.  This allowed me to see what the voltage drop was across the resistor/coil during welding.  (Recall I sized the resistor for 0.05 ohms, expecting to see about a 6-volt drop across the resistor during welding so that I would have 30 volts on the rod.)  Note: Since the resistance of the coil was actually 0.06 ohms, the voltage across the resistor/coil during welding gives the welding current via I =V/R or I = V/0.06.  Thus, each volt means 16.6 amps is passing through the resistor/coil and the welding rod.  So, here is a little table of volts versus amps for the resistor/coil:Volts.......Amps5............836...........1007...........1178...........1339...........15010..........16611..........18312..........20020..........333Volts on the welding rod would be approximately 36 volts less the volts across the resistor/coil.Note: A digital voltmeter was not the best choice for this as the digits fluctuated with variations in the arc.  The results given here are at best an approximation as the readings varied.WeldingI tried a variety of rods then repeated the measurements after placing several pieces of steel inside the bucket (*=Steel inside coil).Here are the numbers I noted during welding.Rod..........Diam..........Volts Coil..........Current..........Volts Rod6013..........5/64..........5 – 7..............83-117..........~29-31............................14.5...............241  ............Short circuit7018ac........3/32..........6-9..............100-150..........~27-30.............................15................250  .............Short circuit............................10-12*..........166-200...........24-266011..........3/32...........9-12.............150-200..........24-27..............................20+..............333  +...........Short circuit.............................6-9*.............100-1506013..........1/8............9..................150...............  .27.............................6-8...............100-133..........28-30Observations1 - Compared to welding with no resistor at 36 volts, the resistor/coil cut down the current to more usable levels – a definite improvement.2 - Compared to welding with no resistor at 36 volts, with resistor/coil the arc was just as easy to start and maintain as before.  (This was the biggest problem when trying to weld with only 2 batteries and 24 volts.)3 - The addition of steel inside the bucket/coil made a significant improvement in the quality of the arc.It reduced the expulsion of metal when the arc was struck (I could hear the steel pieces jump when the arc was stuck.)The higher inductance caused by the steel really shone in making it much easier to maintain the arc as the rod-to-work distance varied.  4 - Some strange effects were noted:With 6011 and the air coil, welding current was 150-200 amps decreasing to 100-150 when steel was placed in the coil.  It was similar with 6013: with the air coil, welding current was 150 amps decreasing to 100-133 when steel was placed in the coil.  However, 7018 AC was just the opposite: with the air coil welding current was 100-150 amps increasing to 160-200 amps when steel was placed in the coil.  I have no explanation for the odd behaviour of 7018 AC.Weld Quality – welding 1/4-inch thick bar stock.In spite of difficulties of maintaining the arc (jam/arc technique), the best welds I obtained using 2 batteries (24 volts) with 3/32inch Lincoln 7018AC. Conclusion so far- Welding with batteries is a challenge.- Two batteries at 24 volts is not really enough voltage for arc welding – there is no visible puddle and the arc is hard to start and difficult to maintain.- Three batteries and 36 volts give too much current for anything less than 1/2 inch thick (However, it does seems great for thick sections).  Adding a resistor to 36 volts to drop the welding voltage to 25-27 works reasonably well.  The addition of an iron-core coil as an arc stabilizer helps a lot.  Possibilities1 Optimizing the design of the steel-cable coil and iron core to maximize inductance may be beneficial for the three-battery system.2 While the addition of a resistor helps control the current in a three-battery system, it would be better to replace the resistor with a solid state device like at IBGT so that one could limit the current to any desired value.3 Adding a low resistance copper-cable and iron-core coil to a two-battery system may be useful to help stabilize the arc.  We still really need a couple more volts though.So where are we?Batteries are expensive to buy, a pain/dangerous to use & maintain and by the time you add an arc stabilizer and maybe solid-state current control, you could have bought a conventional 117 or 220-volt alternating current welder.Unless you are in the field with no AC power at all, I’d say, go for 117 or 220 VAC powered welder.  Even then, you might consider using a generator to power a conventional 117 or 220 VAC welder.  If you want ~70 amps AC welding, get a cheap ($80) 117VAC stick welder.If you want ~90 amps DC welding, get a cheap ($130) 117VAC inverter-stick welder - that can also do DC TIG.Maybe there is available a cheap (~$230) 220VAC inverter stick/TIG that outputs about 150 amps DC – that would be a reasonable solution for stick.Me – what next?I’d like to look into adding a low resistance copper-cable/iron-core coil (arc stabilizer) to the two-battery system just to see if it will help enough to make and maintain an arc.Of course, if you have suggestions, I am listening.Rick V
Reply:HeatI forgot to mention heat (power dissipated) in the resistor/coil using three 12-volt batteries.The measured resistance of the coil comprised of 50 feet of 5/16 inch galvanized steel cable was R=0.06 ohms.  During welding I measured currents of 100 to 200 amps through the coil, with the average being about 150 amps.Power = Current^2 x Resistance.  For the coil, this power goes into heating the resistance/coil.Heat at 100 amps = 100x100x0.06 =    600 wattsHeat at 150 amps = 150x150x0.06 = 1,350 wattsHeat at 200 amps = 200x200x0.06 = 2,400 wattsHeat at short circuit ~400 amps = 400x400x0.06 = 9,600 wattsThat’s the theory, what did it feel like in reality?After welding for about 20 seconds or so, the coil felt warm to the touch.  I kept checking almost every time I welded with different rods.  At no time did the coil seem hot – just comfortably warm; I could hold my hand against continuously against the coil.  After a 30 second session with 150 – 200 amp draw, the coil felt quite warm overall – individual turns could feel ‘very warm’ immediately after welding – but they never felt ‘hot’.  I never had to whip my hand away!Now the temperature in my garage where I did the welding was cool, about 50 degrees F (10C).  The coil seemed to lose high heat quickly but maintained lingering warmth.Smaller WireGiven the above, it appears that I could have gotten by with smaller-diameter steel cable.I’ll spare you the math, but for 200 amps and coil resistance of R=0.06 ohms, we could change from 50 feet of bare 5/16 inch diameter wire to 18 feet of plastic coated 3/16 inch diameter wire (1/4 inch diameter with the plastic coating).  Plastic coated wire makes coil construction easy, as you don’t have to worry about proper spacing on the turns – just wind the turns tight to each other.Below are some handy-size coils – that can be stuffed with scrap steel to raise the inductance for good arc stabilization effect.- If we use a cardboard mailing tube of 3-inch outer diameter, the coil will have a circumference of about 10 inches, contain about 21 turns and be about 5 inches long.- If we use a cardboard mailing tube of 2-inch outer diameter, the coil will have a circumference of about 7 inches, contain about 31 turns and be about 8 inches long.InductanceInstead of 50 feet of cable, we have only 18 feet.  That will decrease the inductance because we either loose coil diameter of number of turns.  Inductance is proportional to coil area or to the number of turns squared.  The ratio of wire length or number of turns is 50/18 = 2.79.  So our inductance will drop a factor of 2.79^2 = 7.8 times.  However, we can now stuff the 2 or even the 3-inch cardboard tube with steel, something that was not possible for me when using an 11-inch diameter tube (I had a very poor fill factor, maybe 5% of the total area).  Thus, it is likely that we can maintain a similar or higher inductance and get good arc stabilization performance.Note: The magnetic field in the centre of a coil is zero.  So if you don’t have much steel/iron for stuffing the inside of the coil, place your steel/iron around the periphery – not in the centre.Rick V
Reply:This thread is just busting me up