Welding with no power?

When building a house on a metal frame, eventually you are going to have to deal with the need to weld something.  No, really.  It’s the most logical solution. And unless you are building your container house out where you have a nice power supply (a 6+KVA generator would help), you’re going to have to figure out how to weld without the unlimited power we city dwellers have come to expect.

MIG welding headCertainly one solution is the generator->standard 220V welding setup.  But there’s the first rub.  You need a sizeable generator to power a welding rig (usually ~5+KW minimum) if for no other reason than to get the 220V plug which most MIG welders need. This might be fine if you already want a large generator as backup for your place, but most people would do fine with a 1-2KW generator, rather than the much more powerful 5KW scale generator. In addition to the size, there’s the fuel consumption. Going from hours per gallon to gallons per hour between the two ends of the spectrum.  There’s also getting the generator in place (again, not an issue if you plan on keeping it in/near the cabin), especially if you decide to rent one, where a good road makes this easy, but if you’re like us, where we don’t have a good path to where the containers will be, it certainly adds to the challenge!

One potential solution, given the fact that we’re looking at solar as a key energy provider for our studio, is to weld with DC.  It turns out that welding systems are DC anyway, but usually there’s a large AC/DC conversion along with start control and other fancy bits within the box that the welding head is attached to.  So why not just run direct DC?  Well, that’s just what’s avaiable, either with built in batteries (something like: http://www.hobartwelders.com/products/battery-powered/trek180/) or standalone with your own batteries (as in: http://www.readywelder.com/).  But since these systems are fairly straight forward, and if you can get away without the shielding gas supply, you could build your own (as shown here: http://www.instructables.com/id/SpoolGun/)!

I’m going to look at the build your own route myself, as I already have the equipment for a fairly sizable solar platform, and as long as I can get away with fluxed welding wire, this should work out really well! Interestingly enough, there’s a “solar golf cart welder” instructable as well (http://www.instructables.com/id/SolarWelder/)  which at least based on the commentary leads me to believe that I’ll have plenty of power for small welding jobs, though not perhaps for the behemoth job of building out the metal shutters. It does make me wonder about solar plus a generator->battery charger setup. As this might be an interesting “hybrid” setup. As the comment went, you might draw 150A for welding, but only for a short time.  And if you can feed in 30-50A (plus whatever the solar provides), it might well be that the batteries act more like a big capacitor rather than managing the longer term power storage that batteries are known for.

Clearly, there’s still a lot to learn about how much actual power is required for welding, and what the best methodology will turn out to be, but we’ll experience many of these options soon enough!