How To Weld With Car Batteries (And Why It’s Awesome)

How To Weld With Car Batteries (And Why It’s Awesome)

A while ago I was faced with the challenge of wanting to weld, but living in an apartment where that was out of the question from the start.

Eventually I bought a truck that I used as a rolling workbench to pull up somewhere in nature and craft away – but that posed the new problem of power supply. With all other tools that is no issue at all thanks to 18v battery tools (I love them!) – but welding without access to shore power is very complicated.

In essence you have three choices:

  • Buy a professional lithium battery welder (that costs 3300€ though!)
  • Buy a welding generator (the cheapest one I could get would be 600€)
  • Buy two car batteries and thick jumper cables (total cost of roughly 400€ with large batteries)

So cost wise the car battery solution is already preferable, but obviously this is the most hacky option of the three. The first one, the professional lithium welder is basically that, just properly made but for a hobby purchase it is just outrageously expensive and cost prohibitive.

The generator seems like a good middle ground, especially considering that it can also power other tools or charge batteries but well, it’s a generator. That means it is huge, it is heavy, has a lot of moving parts, you need to fill it up with fuel and oil. Also, now that I only have a car and not a truck anymore I dont really want that mess in my trunk where it might fill the car interior with fumes or oil.

And then, the key part why I don’t want a generator is that it is not really on-demand power and you will keep it running for minutes, hours even at a time between welds that only take a couple seconds to make.

So then I was back at square one, deciding to go with the battery solution that is now in its second iteration and works really well for my use case of making scrap art with it.

Obvious disclaimer: Do your own due dilligence before you attempt anything

While I have definitely gotten this setup to work and it even works well for me there is a lot of research you should do upfront. The rods, the thickness of jumper cables, modding an electrode holder onto one end of the jumper leads are all variables in this setup.

Safety is really important when welding, make absolutely sure that you wear proper protection (eyes especially, just spend the 50-70€ for a self-darkening welding helmet). Also welding gloves are a must, they cost just 10 bucks or so and either a thick leather jacket or proper welding clothes go a long way. A lot of this stuff can hurt you and burn things so be careful.

The benefits of using car batteries to weld

The good part though is that in its most basic form all you need is two sets of jumper cabless (you need three total to connect two batteries and have one cable for electrode and the ground) and two batteries.

The benefits here are plenty:

  • It’s relatively cheap, I went with expensive batteries but really you could bring the total cost down to ~200 bucks total.
  • It is on-demand power and does not annoy you or waste resources with a running engine.
  • It works really well and reliable once you figure out the right size of electrodes to use.
  • You can – though probably shouldn’t – weld pretty much any thickness of steel you would normally encounter. This is commonly used for emergency vehicle repairs like welding broken axels while out on the trail and such, the end result is absolutely usable.
  • DC welding is apparently more consistent, cleaner than AC welding so you even get a slight benefit.
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The (simple) setup

What you’ll need:

  • Either two sets of (thick) jumper cables or one set with another third cable to connect the two batteries together.
  • Optional: Replace the black clamp of one jumper cable with a proper electrode holder. That will make your life easier but you can also just clamp the electrode into the clamp and not „ruin“ a set of jumper cables.
  • Two batteries of 12v each (or if you can find 24v you need just one battery and can skip that connector mentioned above).

That is all you need, now we get to the (simple) setup.

  • Put your two batteries next to each other
  • Connect the negative of one with the positive contact of the other
  • Use your black jumper lead and connect it to the other free negative contact, the other end is where you put your electrode later
  • Connect the positive contact (the last one that is free) to the red cable, this is your ground clamp
  • Connect the ground clamp (red) to your work piece
  • Put an electrode into the other cable (black) and put on your protection, then start welding.

The main issue you will likely face in the beginning is an electrode that sticks to the surface, then it will quickly start glowing, overheat and eventually burn through. This is not much of an issue because the rod serves as a sort of natural circuit breaker and won’t harm the whole system, but you will have wasted a rod. If you notice that happening (it will) you can release the electrode clamp and break the circuit that way, if you are quick enough you can even reuse the rod.

Apart from that you will find that it’s surprisingly capable for all kinds of hobby welding like scrap art, making decorative elements, furniture pieces. You can do a lot with this like welding farm gates and such, but I would always advice that you think about the load and stress that you’ll end up putting the final results to.

Will it hold? Quite possibly. Do you want something to break down while you hold onto it, while it carries heavy, expensive loads or something like that? Probably not.

But I can attest to the structural integrity of these welds, I once welded a little bolt to my truck frame so that I could hang up my hearing protection and that thing was so sturdy that I could pull myself up on it with my full weight.

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