Welding with two car batteries actually works – and surprisingly well
This is the kind of post that has to come with an obvious disclaimer: This is stupid and not how you should do things if you have any other option — which I don’t.
I use a 1998 Mercedes flatbed truck as a workbench on wheels to follow my crafting passion and most of my tools run on battery power. That works wonderfully, cordless tools have made such a massive jump compared to when I was a kid that you can not feel the difference anymore.
Even cordless welders exist today — but they are in the 3,000€ range which was a little much for hobby purposes. That’s how much the whole truck cost me and that was a little much for something I don’t exactly need to survive.
But I really wanted a way to weld — even if just scrap art and not exactly structural parts of bridges and pipelines. So I researched, found out that a generator powerful enough to run even a small welder is huge, loud and expensive — actually more expensive than just getting the professional battery powered one.
And then I researched a little more, found out about battery welding but the way it is portrayed online makes you look past this surprisingly capable option. It wasn’t until I read a forum post by a guy who said that he used it to build a hunting tower away from all power sources before I thought about it more seriously.
It does actually work
After lots of research I eventually went ahead and bought everything I needed — more on that soon — and was a little surprised to find it working.
I had never once welded anything to this point so you can add a lot of “how to stick weld” video tutorials to my research list and of course it was just about as rocky a start as you imagine for improvised tools and no practical experience — but the more I use this method the less I want something else.
Sure, one day when I can find and afford a real workshop I will switch to a small welder immediately but for the time being this battery welding thing works really, really well.
Just to give you an idea I just completed this scrap art project for our team leader (leader and ladder are the same words in German) where we slapped little pictures of us on top.
This is honestly one of the things in life where I wonder why not more people are doing it. I have welded a little bolt to my truck to hold my hearing protection and hat whenever I don’t need it — just a little bolt but that thing is welded on strong enough to hang my full weight on it.
So while I certainly wouldn’t use this method for any safety-relevant parts and pieces you can actually build some pretty damn strong connections using it. Definitely enough to make scrap art that doesn’t fall apart.
What you need
Let me quickly explain what you need — it is not a lot at all but it is also quite expensive so again: If you have another option a hundred-dollar welder will do a better job with less hassle but it also won’t be this mobile.
- Two 12V car batteries. Some recommend three but two work just fine.
- Two thick jumper cables, get the good ones for this purpose as they won’t run hot and melt on you.
- Either a third jumper cable or a battery connector cable. Both work, I have a connector cable that sucks and exposes bare copper so I’ll probably switch to another cable soon.
And that is all you need for the actual welder, of course there are some necessary supplies to actually make welding possible:
- A pack of welding rods, I use 3mm rods but I have no idea how that translates to imperial measurements.
- A welding mask. Do yourself a favor and get one of the auto-darkening masks, they make all the difference between hating and enjoying to weld. I have one from the hardware store for seventy bucks and it works perfectly.
- Welding gloves made of full leather, mine cost like ten bucks and they will last forever.
- Some kind of thick clothes, I have a leather jacket that I already ruined while magnetfishing and so I use that. Never had any issues with this but it does get hot during summer.
And that is all you need to start welding.
How to set things up
Setting the battery welder up is actually much simpler than you would expect:
- Connect the positive of one battery to the negative of the other using the connector cable or third jumper cable.
- Connect the black jumper cable to the remaining negative and the red to the positive. Actually the colors don’t matter but it is good to stick to this habit.
- Bent the black (negative) jumper cable a little flat with a pair of pliers so that you can fit a welding rod in there securely. If it only sits in there loosely you can create resistance that makes the rod and jumper cables fuse together — don’t worry too much because the rod will then act as a circuit breaker. But you will notice this as soon as the rod starts glowing, just disconnect the clamp in that case and you’ll be fine. That happens with at least one rod on each day I weld and I still use the same setup without issues.
- Connect the red clamp to your work piece (make sure they are clean)
- Start welding. Refer to a stick welding tutorial in case you have no idea about this — but seriously in that case do more than just your due diligence. Just because this stuff worked for me without any prior experience doesn’t mean it’s a smart thing to do — it is not and I am well aware of that fact. Welding is serious business and not to be taken lightly — you can kill yourself if you mess things up badly enough.
So why would I even do this?
Good question, I honestly think most people will never need this skill or knowledge.
It does come in handy if you do off-reading and need to improvise repairs to get back onto a road — most trucks come with 24V or two 12V batteries or maybe you have a friend with you.
Another reason to use this would be off-grid homesteading — but also farm use. I remember at least five occasions during my summer jobs where this could have saved us days of work when machinery broke and had to be brought back to the farm for repair. Tractors definitely come with large batteries and even high-powered outlets that could probably run a regular welder but somehow no one ever thought of that.
And lastly of course my own usage makes quite good use of this technique — in fact for me it is the preferable choice for some weird reason. I hate the noise of generators and I would need a place to store that massive hunk of steel — and generators are a hassle to maintain in my limited experience. When they break it takes days to get spare parts and you could buy this whole setup from any hardware store around you if you needed new parts.
I hope you found this little explanation useful, it is certainly a dangerous and stupid idea but then again it definitely works for me. I still hope to upgrade as soon as I figure out how.