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Trip

Solar powered mig welder

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Hey yall,

I was reading a old issue of Country side Magazine, and I wanted to share this article about a solar powered mig welder. This article is from Volume 94 Number 6 November/December, 2010, written by Rex A. Ewing Colorado.  Hope yall enjoy reading it as much as I did.

Article used with permission of Country Side Magazine

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This is a story built around a tool shed; a shed, where for the past couple of years, I've been welding, grinding, drilling and sawing all manner of materials, providing that, after 11 years of living off the grid, I can still be humbled by the power of a single solar module. 

 The shed in question has evolved over time from a handful of meager expectations and a few modest requirements. All I really wanted was a tight little packrat-proof building to store the overflow from the farm we'd moved from two years before. Since we'd spent those previous two years building a log house, all my precious treasures- ranging from a moderate collection of tools to a cornucopia of nuts and bolts and assorted metalliferous oddieties sufficient to make a yuppie sneer or a redneck salivate- were crammed into a 12x16 foot fabric tent-shed.

The fact that the fabric shed kept all these things (stored higgledy-piggledy on makeshift shelves and racks buildt over and around boxes and cans of every size and stripe) high and dry, only made it more hospitable to the legions of mice and packrates that took up residence almost as soon as the shed was erected. and in no time at all they were claiming squatters rights and getting disturbingly surly in their expression of them.

The new shed was conceived with the singular purpose of doing exactly what the fabric shed did, with the additional expectation that its wood and stucco walls would prove to be a definitive barrier to that mountain's robust rodent population. And in that regard it has performed admirably since its completion.

I decided to wire the shed for 120 volt operation, even though the nearest power source was our new off-grid log house, 100-plus feet to the west. Figuring that I would use electricity there only rarely, I terminated my wiring into an RV-style junction box with a male outlet. That gave me two options for powering the new shed: I could either run an extension cord to the house or plug the shed into the large stationary generator resting on blocks outside it. Neither option was wholly satisfactory. The generator burns gasoline and does so at an unpleasant decibel level. On the other hand, whenever the shed is plugged into the house that requires the big, beastly 220 volt well pump to pull water up from 500 feet down.

So after a couple of years and at the least that many homespun blackouts, I decided to install a separate off-grid solar system to power the shed. Thriftiness was my guiding princible: a single 24 volt, 175 watt solar module to provide the raw wattage and eight 6-volt, 225-amp-hour T105 golf-cart-style batteries to store it; and old Trace C-40 charge controller; and an Aims 2,500-watt RV-style modified sine-wave inverter (the kind that you can't plug into a generator for battery charging) to convert the batteries 24-volt DC into 120-volt AC.

I honestly didn't expect much. compared to the house system with 2,320 watts of solar, 1,000 watts of wind, and 24 big, heavy L-16 batteries, the 175-watt shed system was a real featherweight; good for some nighttime illumination and a modest amount of sawing, grinding or drilling from time to time, but not much else Or so I reckoned at the time without actually putting a pencil to the matter.

The first glimmer that my system was brawnier than I was giving it credit for came whenI picked up a small 120-volt Lincoln MIG welder at a fire-sale price from a friend who was moving. I already had a MIG in the garage, set up for stainless steel, but my friend was hurting for money so I took the welder off hise hands and set it up in the shed, rigged for mild steel.

Rated at 20 amps, even this small welder can draw down a fair-sized generator. Still, I calculated my cheap little 2,500-watt inverter-with a commendable surge rating of 5,000-watts- would run it easily, which it did. The question was, how long could I run the welder before putting the batteries in jeopardy?

Slowly and cautiously, I tested my small system and the new welder, pushing it a little more every few days, just to see how long it would take the batteries to charge back up again. I was pleasantly surprised to discover that, as long as it was sunny, the batteries would invariably reach full charge the day after each o fmy progressively more energy intensive projects.

but that sort of pampering wasn't really telling me what the system could do. So I devised a more serious test, an endurance trial of sorts where I could stress the system while constantly monitoring its vital signs. I did this using a Watts-Up meter to measure various loads the system would experience throughout the "test," as well was th cumulative energy usage. B being plugged directly into the inverter, the meter would be measuring every last watt, including the energy consumed by the compact-fluorescent lights overhead.

To test the system, I built, appropriately enough, a welding cart on casters to hold the MIG welder and a small oxy/ acetylene torch. All told, the cart required over 20 separate pieces of pipe, square tubing, angle and flat iron, all of which had to be cut with a bench-mounted cutoff saw (1,800-watts at full load). I also drilled over 30-1/4" and 5/16" holes with a 5/8" drill press (480-watts) and did a considerable amount of grinding using an eight inch bench grinder (480-watts max). the project also required a small amount of wood cutting using a worm-drive saw (1,350-watts) and, of course, the equivalent of a six-foot-long 1/4" bead of weld

The welders energy usage was the most surprising measurement Although it had laid down nice, smooth beads with hardly and spit and spatter (working, as it was, in an inert co2/argon environment) the energy usage was all over the board, jumping between 850 and 1,800-watts which, in any case, was considerably less than I had anticipated, particularly since I was suing the highest voltage setting.

All told, the entire five-hour project consumed 1.224 kWh of solar electricity- a reletively small amount of energy; certainly less than I would have thought. But then again, i'm not a solar battery; I just used the energy, I didn't have to hastily supply it via a steady cascade of trillions up trillions  of rapid-fire chemical transformations.

How did my small bank of T105 batteries weather the ordeal? just like the stalwart powerhouses I've always known these batteries to be. The total energy usage was well within an acceptable rand. At 225 amp housr at 24 volts, giving the bank of eight batteries a total of 450 amp hours at 24 volts.

since volts x amps= watts, 450 amp hours x 24 volts =10,800 watt hours, or 10.80 kWh of capacity for the entire battery bank. Dividing my total energy usage (1.224 kWh) by the total battery capacity 10.80 kWh), I found that I had used a little over 11% of the batters total capacity: 1.224 devided by 10.80 =  0.113. 

Since I build the welding cart in the middle of a sunny day, the batteries were charging at over 120 watts the entire time. And by shutting the inverter off when I was finished (as I always do), the batteries were back up to charge by the end o the next day. 

the total cost for the system at today's prices, including the solar module, charge controller, batteries, and inverter, plus circuit breakers to isolate each of the system components (but excluding wiring and other materials, that a lot of folks already have on hand) should run less than $2,000.00, depending on how savvy a shopper you are. Solar modules in the 200-watt rand for instance, can be had on the internet for around $2.00 a watt.

Got an old outbuilding on the back forty waiting for a spark of illumination? A little stand-alone solar system might be just what it needs.

Rex A. Ewing

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Sorry, but his "120v" welder was probably an old Lincoln Weldpak 100 model. It's basically a toy that will make a crappy bead on maybe 1/16" steel. I cant believe his 120v welder is making any worthwhile penetrating beads. Spending $2,000 for a " junk" solar welding set-up, isn't going to cut it for anyone serious.

He would be better off buying a harbor freight 80 amp stick inverter (model 91110) and plug that into his generator. Using 1/16" electrodes will give him a "fair" at best bead on sheet metal.

Im afraid that the $2,000 solar welder set-up the author describes, is a joke. A standard Lincoln 140T or 140C model needs 25 amps as recommended by Lincoln Electric, in order to get MAXIMUM output potential. Pulling the full 25 amps from either of those two machines will usually cause a person using only a standard residential (garage) 20A circuit, to play "musical circuit breaker" while welding on the highest settings.

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OK Thermit, It is an interesting topic so don't throw the torch on it just yet.

How many S. panels and batteries would we need to have an off the grid fab shop to be proud of?

Maybe a bank of spuds hooked up in series? Hmmmm.

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Well, picture this..... Any amount of batteries you need for your fab shop, would take up 75% of your shop floor space, thus crowding out your tools. Second, is a pic of what your "solar" welding + battery power banks would more than likely look like.  As Catain Kirk used to scream out to the engine room, "Scotty, I need more power!"   

 

Solar powered welding on a "hobbiest" scale, isn't gonna cut it.

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the photo has nothing to do with the thread . and every thing to do with Very poor welding .

 

By the way if a simple 40 bank of batteries can run a house and all of the things in it properly this system will / would run a Small welder .

 

Good luck with your Welding

 

Sam

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Trip- Thanks for sharing this.  I've been doing research on this very topic and somehow I ended up here which is ironic because I did not expect to find a post like this on IFI.  I know its an old thread but I am curious if anyone reading this has built a similar system.  I can certainly relate to the author of the article and have a bunch of my stuff jammed into one of those Costco carport tents after buying some a house and some property with no outbuildings.  Building some sort of small pole shed for a smithy is on my list but unfortunately much further down.

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Well as he was referring to to a small hobbiest / homestead shop and I have gotten up to some fairly stupid welding with both my Lincoln and Hobart 120’s (hint, preheat, good bevels, multipass and short cycles (40% Lincoln and 60% Hobart) will make substantial welds in 1/4-3/8” stock. Now that we have a 220 Hobart they are not subjected to such abuse. 

Certainly a full time fabrication shop might benefit from a large desire generator as primary power with solar and batteries for lighting and incidentalsbut that wasn’t what the arrival described. Their was a time when a fabrication shop ran on steam,  and even further back nothing but strong arms. 

 

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When I was in Indonesia there were a lot of  welders run off small diesel engines; if you had a large project you dragged everything out onto the side walk and started welding.

I was wondering how such a set up could be run off bio diesel; but I'm lucky enough to live on the grid.

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