Introduction: Batteries + Jumpercables = DC Welder

Picture of Batteries + Jumpercables = DC Welder

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.
I happened to have some nice juicy batteries in the form of a Golf Cart.

Here's me welding a trailer hitch with 1/8" 6011 rods. Welding current peaks at around 140-150 amps with these rods and around 120 amps with 3/32 6013 rods according to a Fluke 1010 clamp probe.

Greatly inspired by South Africans battery-welding their landrovers.
More battery welders
Also check out this great homemade AC stick welder.

That said, read the specs for your battery. Big ones are designed to produce enough current for welding. Don't let the nay-sayers keep you from trying it. Check your batteries and don't overheat them. Lead-acid batteries can go into a thermal-runaway self-discharge mode.

Action photos by Andrea, video by Pete Lynne.

Step 1: Cables and Rod

Picture of Cables and Rod

Here's the stuff.
The jumper cables were $12 from Harbor Freight.
The strip of bicycle innertube is optional, to wrap the end of an alligator clip and make it grip harder.
If you're feeling fancy you can replace one of your alligator clips with an electrode holder.
This nice one was made in India and cost $7 from Harbor Freight.
The welding rods I tried are 3/32" 6013 and 1/8" 6011, 5lbs for $6 or so. Available in Africa, S.America, anywhere.

You'll also want to wear gloves,
and a welding helmet, $16 from Northern Tool

Step 2: Alligator Clip Orthodontics

Picture of Alligator Clip Orthodontics

Bend the alligator clip's incisors forward so the canines can grip the rod properly as seen in the 2nd photo.
Strengthen the alligator's jaw muscles with a wrapping of bicycle innertube strip.

Step 3: Batteries!

Picture of Batteries!

My golf cart has 6 of these 6 volt T-105 size batteries that I bought used from THE GUY WHO MADE THEM!!!

They're in series making 36 volts total. I can clip in anywhere in the chain to get 36,30,24, etc. volts.
The batteries have about 220 Amp-hours capacity, so that means I could weld at 150 amps for more than an hour (consult books printed on paper for the details) without recharging. Plenty good since I'll never have a project with enough metal laid out ahead of time to spend that much time a-welding in a day.
If your batteries aren't as nice as this, don't worry, you can do plenty of welding with three old car batteries in series.

I got these from the guy who made them?
That's right, a family run battery manufacturer right in Sausalito in a little workshop.
It's really amazing, like an old time blacksmith's shop, but high-tech. They can make any size battery.
Alrick, the proprietor, grew up making batteries and he really knows his stuff.
He sells batteries to all the big boats there, and he knows exactly how long every brand of battery lasts in every set of conditions.
Don't bother him about your electric car though, he's been plagued about that sort of thing enough already.

Arc battery company
90 gate 5 rd. sausalito ca 94965

Step 4: Welding Tests

Picture of Welding Tests

I welded on 1/4" thick cold-rolled mild steel plate.
I used DC reverse-polarity at 36,30, and 24 volts.
I used 1/8" 6011 rod and 3/32" 6013 rod

Step 5: The Welds

Picture of The Welds

A short arc but very hot. It melted deep and fast into the 1/4" plate.
I couldn't have stuck the rod to the plate if I wanted to.

These are the welds after chipping and brushing the slag off.

I did the right hand weld first with 1/8" 6011 rod at 36 Volts.
I've had the rods for a while and they're a bit damp and splattered a lot.
It's a deep good weld as you can see in the next photo of the backside of the plate, where it's melted through.

The mess at the top of the middle weld is trying a 6011 at 24 volts. Not enough juice, a lot of splattering. The full length bead next to it is a 6011 at 30 volts.

The left hand weld, the best looking one, is a 3/32" thick 6013 rod at 30 volts.

This golf cart is a good welder and I will definitely use it to weld projects in the future.

Step 6: Arc Stabilizer and Stinger

Picture of Arc Stabilizer and Stinger

Thanks to readers who recommended putting an inductor in series, called an "arc stabilizer".
Zan and I made one from a transformer we scavenged from a dead microwave oven. We used this method to chop out the secondary and wind 20 turns of 10-guage wire, which is all that would fit.
We left the primary intact, it doesn't affect the function here. An inductor gives the current "momentum" to blast through bits of flux and rust that get in the way. The arc sputters a lot less, welding is easier, and the welds are better.

I got a great Indian-made stinger (electrode holder) for $6 from harborfreight and replaced one of the jumper cable clamps with that.

Then I welded some repairs on this very badly rusted boat trailer. Too pitted to grind clean very well. I used 1/8" 6011 rod at 36 volts and it was fabulous. I melted good deep welds into all that rusty metal. Very satisfying.

We've got a self-propelled welder!

Step 7: Cutting Steel With a Stick Welder

Picture of Cutting Steel With a Stick Welder

The bumper hitch on my 1978 Toyota truck was rusted rotten.
Ray and I used the golfcart welder with 1/8" 6011 rods to weld some beefy reinforcements on it.

The big toroidal series inductor seen here came from [ ACCRC] Maker Day. I should put a few dozen more turns on it to really smooth out the arc. We did some strong agricultural-style welding that isn't going to break or appear in textbooks.

Here's Ray cutting holes for the trailer safety chain to hook on.
We dipped the rods in water and then blasted and pushed the steel out of the way. It works well and makes a surprisingly clean hole while using less rod than you'd think.
Thanks to a reader who suggested dipping the rods in water- I can't find your comment now, what other nifty tricks do you have up your sleeve?

I also tried an improvised air-arc torch using compressed air. It didn't work at all. The air blast blew the arc away, chilled and froze the molten metal instead of burning it. I guess that's why air-arc cutting torches use 500 amps or more


pauldash29 (author)2017-09-20

Fantastic. You can do amazing stuff. The golf cart already has batteries in aeries, right. If you are starting w 3 car batteries, is jumper cable good enough in between batteries or need proper car connectors?

GregoryS57 (author)2016-10-02

On the inductor (Arc stabilizer), could you wrap your coils around a round plastic rod storage box filled with welding rods as the iron core? Since you've got to have rods with you anyway this seems like it would accomplish both. Also, it seems like the 10 gauge wire you're using in the inductor is a "resistor" in the system... aren't the full amps of the circuit flowing through the inductor wraps? Does this smaller inductor wire get hot?

R-A (author)2016-03-20

I'm quite curious, how do you control the Amperage when welding with batteries?

BuddyJ1 (author)2015-03-14

hello, i am buddy jeans from arizona. i am very excited to have this build as my next project. i love learning the right way in stuff. then i practice until i feel confident in exploring the limits. thank you for the tips and i will be safe.

BuddyJ1 (author)2015-03-14

hello, i am buddy jeans from arizona. i am very excited to have this build as my next project. i love learning the right way in stuff. then i practice until i feel confident in exploring the limits. thank you for the tips and i will be safe.

andy.knote (author)2014-12-18

I've wanted to do this since I saw them welding this way on "The Colony" Thanks for posting the Instructable.

Great Instructable. Good photos, nice job of covering the little details, great step-by-step instructions. Nice Work!

Zuma07 (author)2012-09-06

Of course I don't have access to it but how would or could one deep cycle battery from an rv work for this?

kendall giles (author)Zuma072014-07-31

look at my comment above I use marine batteries

kendall giles (author)2014-07-31

I used two marine batteries, with 9ga wire coiled to be the resistor between the two batteries, more wire= more resistance. I needed at lot more resistance than in the last pick but needed it small also so I coiled the the wire around the jack Handel so the coils will be the same size. I can't tell you how much resistance it is but I have several different coils of different sizes to very the amount of power depending on the welding rod you use, also the coils produce enough heat to melt a screw driver, when incerted inside the coil after being used for over a few hours

HammE (author)2013-08-11

How could you control amperage? I'm just unsure of that

HammE (author)HammE2014-03-12

Also, would that be able to weld mild steel tubing for applications like welding a go kart frame?

smpash (author)2012-02-02

How big of a hole does that thing make when burning though metal?

wtuck (author)2011-11-03

so I understand the wiring! What kind of amperage, and duty cycle will a microwave transformer take?

fishnfreak18 (author)2010-10-10

will the golfcart batteries still hold a charge and function correctly if u weld with them?

hintss (author)fishnfreak182010-12-22


sconner1 (author)hintss2011-09-26

I bet deep cycle are better for this application but car batts will will work too, they just don't like being "deeply" discharged as much.
Golf carts use deep cycle batts already.
Just try not to overheat them nor recharge while still hot and everything should be fine.

All batteries eventually wear out.
Sometimes you can revive "dead" lead acids with a little epsom salt.
This make it possible you could "recycle" (more like reuse) discarded batteries you can get for free.

hintss (author)sconner12011-10-10

"Sometimes you can revive 'dead' lead acids with a little epsom salt."

or a welder...

okie1685 (author)2011-10-05

i was driving throught ok. back in 1972 when the drive line on my big rig started slipping. the weld that kept the ujoint conneted to the driveline broke.
a farmer with about 10 old batters in the bed of a pickup had me back on the road before the engine in my truck got cold.. no charge thanks again mister rouse.

xBrainstormerx (author)2009-06-15

hey how you doing? okay first of since I'm trying to weld and know nothing about nothing can you tell me whats that circular piece of object that has two clamps attached to it? what is it ? It looks like a coil wraped in a circular shape but used to do what? I'm clueless nice project Its real nice!!!!!

StCanna (author)xBrainstormerx2010-05-26

Hopefully by now you have learned that that big iron donut is a toroid.  Google or just wikipedia "toroid"and you will get better explanation than i have the patience to type here.

sconner1 (author)StCanna2011-09-26

I'll tell it in brief.
The coil acts as a half of a transformer or an electromagnet.
DC current flowing through creates an magnetic field.
When the arc stops so does the current and the field collapses, but in so doing it induces current in the coil in the same direction like a magnet passing over a generator coil but only for a very brief time.
This effect will help keep the arc going or kick-start a broken arc.
A good analogy would be that it's like the momentum a flywheel gives to an engine between the power strokes.

mrwolfe (author)xBrainstormerx2010-06-17

That round thing that looks like a donut with wire wrapped through it is the torroidal inductor. It's used as an arc stabiliser (see step 6)

toogers (author)xBrainstormerx2009-10-24

toogers (author)toogers2009-10-24

oh, sorry.acccident

leebryuk (author)2008-03-26

Hate to be a downer, but the chemistry behind this eventually moves toward tragedy. An arc welder costs easily less than $100 from Harbor Freight and is much safer and reliable. The helmet is interesting, and I know that it matches the minimum quality requirements. But as someone whose vision is compromised I would feel that a couple more bucks would be worth it. Cheap Beer -yes, Cheap Helmet-No It's the same with brake pads for me. I have bought many brands of pads with varying properties with varying efficiency and have settled on certain facts. Not all are created equal. Most will do the job just fine. But there may be a time that an extra 5 feet stopping power can save you from a lot of pain. Same principal, don't skimp on safety.

Grimarr (author)leebryuk2009-03-01

As long as it covers your face with an ANSI rated shield and has the proper shade in it a $16 dollar helmet will work just as well as the "professional" models that sell for a lot more.

leebryuk (author)Grimarr2009-03-01

No, it will not. ANSI covers minimums. I am a big believer in the functionality of goods from various sources. I purchase items made everywhere on the planet and they are roughly the same. However, it is not worth the short term financial savings versus the long term damage. Do not expect "professional" models to mean pricey. These versions are made for people who weld 12 hours a day in hot, dangerous environments. Plus those guys love angry graphics on their helmets.

Grimarr (author)leebryuk2009-03-02

Please explain how an opaque impact resistant polypropylene face mask and a properly rated shade costing $20 is less effective than the exact same thing purchased in another store for $30. Because I've used them both, and the cheaper one held up a lot longer.

leebryuk (author)Grimarr2009-03-02

Let's go back to my brake example.

My car model came with two braking versions. One was the standard. The other was the Anti-Lock Braking System (ABS.)

They both meet the minimum safety standards set up by the federal government at that time. However, the ABS systems well exceeded the minimum braking safety standard. Get the point?

I don't care for your tone. I'm not going to explain to you why one lived longer than another. To be honest, I don't know why one "held up a lot longer." Besides, what does it mean to "held up a lot longer?" I don't know and I don't much care

Have fun inhaling fumes and burning your retinas out.

Penny wise, pound foolish.

Grimarr (author)leebryuk2009-03-03

There is no tone implied. Your example is not applicable to this discussion. Brake-pads and #13 welding shades do not even begin to work the same way.

Calorie (author)Grimarr2009-03-04

Really? brake shoes and welding filters don't work the same way? I guess that's why I keep crashing my car when I jam those danged welding filters into the old brake pads.

Similes, Metaphors and analogies are the basis of languages (and before comp sci guys get spun out of control, compilers also use oodles of the above.) They allow us to relate ideas that apply from one concept to another.

There is a mental "leap" (well, more like a "hop") that allows a person to understand how things are associated. It is the hallmark of learning, both in basic association and higher cognitive learning.

I'm not sure how to make it much simpler. There is the basic safety standard in which a product must meet certain attributes for reliability, durability and failure rates.

Products can exceed those basic safety standards if the producing company views it as profitable (among other considerations.)
If you still find this confusing, good luck. Talk with a welding instructor and ask him/her to explain the differences between helmets and why the are desirable.

Grimarr (author)Calorie2009-03-04

Thank you for the condescension I really enjoyed it.

Here's my point, in a nutshell. The little green tinted piece of glass in a $16 welding hood works exactly the same as the little green tinted piece of glass in my $30 hood. The only difference is the little piece of glass in my $30 hood is bigger.

Also, please keep in mind the effect advertising plays on the cost of products. The cheaper welding masks like you get at Northern do not have ads in trade magazines.

mpierce333 (author)Grimarr2011-03-10

I think the fellow with a good point above was saying the $50 (or $80) hood is better than the $16 hood (also priced as $30 elsewhere, possibly with a different dimention.)

Cheaper (but minimally rated) filters allow some fraction that over time may be detrimental. Static is static, higher rating means dimmer view. The cheaper auto-flip might work fractions of a second slower (or decay faster?) Again, an accumulated effect over time.

sconner1 (author)mpierce3332011-09-26

Suffice it to say, the battery, jumpers and rods join metal for cheap.
Let's start a new tab for the cost of protecting the human doing the work.

Calorie (author)Grimarr2009-03-04

sigh...well at least you got the patronizing part.

lukeyj15 (author)Calorie2011-05-13

For me, if I were to buy an arc welder, (I learnt at school) then i would probably end up buying a $20 helmet. Not because I can't afford it, but because I would only have a minimal need for it. If I were to weld as part of my job or every week, then I would go out and buy a professional helmet. But, I would be welding a couple of times a year at most, so I have no need for an auto darkening helmet. My school has both a $20 fixed shade and a $100 auto shade mask, and yes, the auto helmet is nicer, but they do provide the same protection.

chrisfrost (author)Grimarr2011-02-03

Not even close to reality . Unless You use a fixed shade #12 or higher will You have decent protection for You're eyes . The problem with that is that You can't see what You are trying to weld . Even the cheap($50.00 H.F.) automatic shading lenses/ helmets provide something like 800% more protection from UV and IR radiation . I have first hand knowledge of this as I used to weld for a living when the automatic shades were new . Before I bought an automatic shade after 1.5 to 2 hours of welding I was seeing sun spots for a while . As soon as I started using the automatic shade I have'nt seen sun spots at all . The sun spots before had been happening for maybe 4 months so I'm hoping there was'nt any permanent damage to my vision . Anyway , take it from me be smart and invest a little in an automatic shade / helmet . Good luck

stasterisk (author)leebryuk2008-04-24

An arc welder is actually free at this instructable.

This is different from an arc welder - it's DC, which is good for steel.

The helmet is perfectly fine. (author)stasterisk2011-03-14

Just so you know any type of welding that uses electricity to make a spark or "arc" is arc welding, weather it be DC straight/reverse, or AC.

southerngent (author)leebryuk2011-02-11

This is intended to demonstrate an off-grid welding technique.

irritant#9 (author)leebryuk2008-04-08

Death does come cheaply. I'd be equally afraid of the Harbor Freight welder. The slogan for Harbor Freight should be: "Our return lines are longer than our checkout lines!"

jammer (author)irritant#92008-12-03

lol good one!!!

bigbadbill (author)2011-04-10

RE: arc stabilizer inductor, something to try; the biggest problem you will likely encounter due to the inductor windings overheating for two reasons:1) you will tend to use smaller guage wire since it is easier to wind, but it will dissipate more heat. the other problem is the insulation will not let the wire cool readily, so try for wire with thinner insulation if possible.enamel insulation is best if it is may have a ready made inductor available already if you already have spar batteries laying around for the project.. use an old starter motor, it is plenty inductive and can cetainly handle the welding current. Weld the shaft or otherwise lock the motor from turning, lest it run away from you when you strike an arc.
Note that any arc stabilizer is goint to cause a voltage surge when you break the arc and ( that's how it restarts a failed arc) and you may get a tingle in your fingers if you didn't do a good job insulating your connections
If you choose to use a rewound transformer for the inductor core make sure you remove or well insulate the unused windings becausethe welding current winding will act as a new primary for the transformer and induce a current in any other windings that remain. you could easily produce hundreds of volts in short bursts as you drag the stick.
please be careful with your sparks, I have been around an exploding car battery and it wasn't much fun

stumppuller71 (author)2009-03-04

Can you please show a schematic on how to wire the microwave transformer to the battery welder? Where does the white wire come from? Thanks in advance!

What I mean is, is the white wire just the second wire from the secondary that goes to the negative? Its a bad angle. And for some reason on my transformer my primary has four leads coming off of it, the two like this one but Ive got two others I just cut the other two off? Thanks

two of them are pwer input the other two are output

Sorry I guess I should leave the question about the primary leads for the microwave welder Instructable as the primaries arent being used here, my bad.

joinaqd (author)2008-12-29

HOLY CRAP!!That toroid is soo big, it might be used as a JOULE THIEF to light up a LOTTA LEDS WITH A SINGLE 1.2VOLT BATTERY!!!i dont know for sure, but anyway nice instructable!!!

Adam Manick (author)joinaqd2010-11-05

Or it can be an arc welder with a button cell. Not enough amperage though.

mrwolfe (author)2010-06-17

Nice instructable, Tim. Very alternative! A mate of mine who's a welder reckons that welding with DC from a couple of car or truck batteries gives you the best arc. Much better than any AC powered welder can.

About This Instructable



Bio: Tim Anderson is the author of the "Heirloom Technology" column in Make Magazine. He is co-founder of, manufacturers of "3D Printer" output ... More »
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