Converting 12v portable MIG welder to shore power

[coachgeo]

Rick V. suggested on this board that one way to solve my problems with my marine batteries getting worn out welding/charging was to convert my welder power to shore power from 12v battery power. REMEMBER my wire feed is powered seperately and is NOT connected in anyway to the welders power supply.

After looking at the short term and long term $$$ and my total goals as a package I decided to go this route.

Here is what I did, but did I do it right?

.Kept the wire feed on a seperate power source

. Got two 120v PEP BOYS: [high-70A / low-55A] arcwelders (was on sale 70buks each)

. Two 20 feet 14gauge extension cords (making these up myself. More on this down below) Manufacture does NOT "reccomend" extension cords but I have too. They do say to put their welder on a dedicated 20A circuit receptical. This is one reason I need extension cords. So I can run too different 120v recepticals not inline with each other.

>>>>>> How I connected them together (Parallel Arrangement)- Using the pieces and parts that bolt to the PEP welders (Which by the way is cheap Chinese Harbor Freight like stuff)

. diassembled the welder rod holders of both welders and using the, nuts and bolts from this I bolted both of these lines to the one larger *8g line that runs power to the wire in my wire gun. I used one of the wire covers from the rod holder to safely cover where this all bolts together.
*8g is just a guess- its large heavy size line that came with my portable welder. It is size of my biggest finger. You know the finger. The one that flies upward when you get cut off by a jerk in traffic.:nono:

. Dissasembled the ground clamps from their wire on each PEP welder. Used the nuts and bolts from this to bolt these two lines together to my heavier ground line that came with my portable welder. It also has a heavier duty ground clamp.

???????????????/Look right so far?????????

If so..... Im not sure what settings I have available to me now
. Do I have to have both welders on the same setting; both high (70A+70A) or both low (55A+55A).
. ORRR can I now have a high (70+70), Medium (70+55), Low (55+55), Low One (70+0), Ultra Low (55+0)

EXTENSION CORD questions

In selecting wire for these extension cords I went down one step from the 16G power cord on the PEP welders just to ensure I have no power loss, Safety etc. Using 14G- w/ground

. welder has a standard 3 pronger and not the special 20amp 3 pronger. For simplicity I kept it the same as this even though I could only find 15A versions of this.

. What color do I wire the wide flat prong on the Male and Female ends? Is these to get the white wire or the black wire; assuming green is ground? Yes the shop I'm in has 20 amp grounded recepticals.

THANX IN ADVANCE. I would search for this but Im not sure what to search for since I don't know the lingo well enough.

[coachgeo]

Once I get this running..... Am I going to be opperating at a peak power LOWER than when I had three good batteries? Don't 3 batteries put out lot more amps that I'll be able to achieve with these two inverter welders? If so by how much will this differ?

[awright]

At least I can answer the cord wiring question. The wide, flat blade is the neutral and takes the white wire. Notice that the wire clamping screw on that blade is nickle plated (= white) and the screw on the narrower blade is brass (= black).

Be sure the open circuit voltage of your Pep boys welders does not exceed the voltage limits of your torch. I THINK there is no limit on voltage with the Ready Welder when you are using an external power cube for the wire drive motor, but check your manual. There is definitely a voltage limit when you are powering the motor off the welding power.

I'd call Pep Boys about paralleling the units. The current range selection process is probably tap-changing on the transformers. If that is the case in your machines, you would have different output voltages on the two ranges and connecting the two together could lead to large circulating currents in the secondaries.---NO!--- Wait a minute. These are DC output machines, arent they? (Have to be DC for the Ready Welder.) In that case the diodes would isolate one unit from the other. So I think it would be OK to run them in parallel and probably ok to operate at different current ranges. However, you may not get all the current you expect on the mixed settings because they are trying to put out different voltages. The machines may not "play well together," on different output settings. But I don't think they will be damaged unless you draw too much current from one machine in the expectation that they were sharing current perfectly. Less risk of unequal current sharing if both are on the same current range.

Have fun.

awright

[coachgeo]

Houstin we have system failure. :realmad: Repeat Houstin we have system failure:cry:

With everything wired like above and using one of the extension cords I get.

1. One welder off, second welder on. Set on low amp (55A)- weld... hahaha.. you got to be kidding barely even get wire hot (.30)

2. Switch to 70 amp- Wire glows red simular to when I had discovered my two dead batteries

3. Same situation no matter which of the two welders I had on alone. About what is expected for one welders juice alone.

4. Switch to two welders both on, both on either setting (70+70 or 55+55) ) - One welder begins to rattle more than the other and I have NO WELD, no hot wire, nothing natta.

5. Switched the homemade extension cord between the two welders and same results. Same welder rattles.

6. Before plugging it all up I looked all over the place for something to tell me if these were AC or DC. BUTTTTTTTTT, Now in frustration I look at the front of the units staring at them wondering what the hell was up and it slaps me in the face. Small little lettering saying
AC ARC WELDER

Is the problem the AC? I really don't have a true "readywelder" Mine is the prototype to readywelder. Just little contraption that uses your own variable speed drill to feed the wire and then a seperate power source (typically two 12v batteries) for welding. I have no clue why the Modern version of the ready welder requires DC. Do all MIG welders requir DC?

[MotoFab]

Hey there Coach -

I applaud your spirit of adventure.

A couple of questions please:
What are you powering the drive motor with? And what sort of wire feeder are you using?

As to the AC Welder power supply problem:
Both welders must be connected to the same AC phase.

Use an AC voltmeter and measure across the Line leads connected to both AC welders.

If the AC voltage between both Lines is nearly zero, then you are on the same phase. Also, if you measure at the welders, it is a good way to be sure both welders get about the same voltage. The measurement is of the differential voltage, you know? You could even play around a bit and place an extension cord on one welder and then make loops in the cord and see what VAC the meter reads.

If your meter reads 240VAC then the Lines are 180° out of phase.

- Jim

[MotoFab]

Oh yea, one more thing Coach.

Once the AC supply has been sorted out, then check the welder outputs.

The welder outputs must also have the same phase relationship. There is no telling how the inside of the box is wired. As it is AC, it could be either way.

Use the AC voltmeter the same way. With the welders powered up, measure between the leads that you plan to parallel. They cannot be connected when the measurement is taken, understand?

The measurement is taken between the two proposed 'work' leads. If the voltage is almost zero then you are good to go.

And another experiment is to switch the welder amp switches and measure the differential in open circuit voltage with the 4 possible switch settings.

Keep the work and torch output lead lengths the same. That is, up the point where they are connected. The connection point can be treated as the 'double amperage' output terminals. And single leads connect from the 'Y points' to the work clamp and torch.

Good on you for doing the test.

Are you using flux or gas?

- Jim

[Rick V]

Holly Crapoly George!
You are lucky you didn't fry up both welders!
Take em Back!

I specifically referred you to inverter type DC output welders - Harbor Freight.

When I first saw this posting, I thought... oh my gosh, I hope he didn't buy AC output welders! But then I saw AWright's posting asking he same question, "These are DC output machines, arent they? (Have to be DC for the Ready Welder.) In that case the diodes would isolate one unit from the other. So I think it would be OK to run them in parallel and probably ok to operate at different current ranges.

That's the deal, MIG normally runs DC, with the wire +ve. The inverter DC welders can be stacked because their diodes protect them from reverse currents. e.g. + 30 volts on one with +25 volts on the other is no problem.
BUT... with AC welders, there is no protection. Either of two things happens:
a) with the same output phase, the 30 volt output of one welder fights with the 28 volts of the other and you get backfed currents.
b) if you happen to get the phases opposite, then Whoa! The 30 volt output of one welder and the 28 volts of the other welder clash in an almost short-circuit sense - I'd expect smoke and flames!

I hope you didn't hurt the welders - cause you gotta return em. They are no good for what you want to do.

Rick

[MotoFab]

It's all good fellas.

In-phase parallel hookup of the primary and secondary windings of simalar transformers is a traditional hookup method. Visualize a 2x larger transformer maybe.

A brief Google search produced this little gem:
http://www.millerwelds.com/pdf/Paralleling.pdf

Excerpt (my highlight):

2-2. Equipment

The following equipment can be successfully paralleled:
- DC Constant Current (CC) Rectifier-Type Power Sources
- DC Constant Current (CC) Inverter-Type Power Sources
- DC Constant Current (CC) Rectifier Engine-Driven Power Sources
- AC Constant Current (CC) Transformer-Type Power Sources

The following equipment is not recommended for paralleling:
- Most DC Constant Voltage (CV) Power Sources (Unless the supply clocks can be synchronized)
- Brush Commutator Design Engine Driven Power Sources
- Motor Generator DC Power Sources
- AC Engine Driven Power Sources
- AC Inverter-Type Power Sources


Coach is good to go after he gets the wiring phase sorted. The transformers were probably not damaged in any way. Hooked up 180° out of phase, they were simply 'swapping fields'. I mean they were using current and all. Kind of like each became the other's 'matched load'.

- Jim

[coachgeo]

I'll admit I did assume they were DC but before and again after reading AWright's post I checked and checked the manual trying to find something to verify this. I know land lines are AC but figured the workings of the machine made it DC. Just didn't expect manufactures to be making AC and DC versions. Why do they do that?

Anyway...... I briefely tested them to assure myself I didn't damage them. Kept it as brief as possible so not to USE them. I then reassembled them and took them back.

Bought a goood automatic battery charger and went battery hunting. Spent hours tracking down batteries trying to match as close as I could to the one that still worked. According to the net no one in this hick town is a dealer for the type of batteries that went bad (Prevailers). Well no one had a marine battery like the good one I have. (1000MCA) So I finally after driving all over the friggen place stoped off at a "gulp" BOAT PLACE where the prices are typically higher than a Tidal Wave for same stuff found at a hardware store. LOw and behold...... they had a Prevailer battery like the two that went bad. I brought mine, told em my charging story and they gave me a new one cause the other was still in full warentee? Shocked the Pee out of me.

But they only had ONE... Go figure. They said West Marine carries them too. It was 7pm by then so West was closed. I'll try them tommorow. May be closed fer labor day. Otherwise I'll wait for their next shipment. Thursday or so they said. I'll make sure to be pickier about how I charge them. Just didnt know gell cells are so different in how you go about charging them. Apparently that happens often but Prevailer wants the biz so they replace them figuring you'll do it right in the future and when ya wear it out, will buy from them again cause they treated you good. I would.

[coachgeo]

Hey there Coach -

I applaud your spirit of adventure.They say invention is the father of neccessitie. I think Stuborness comes into play also :jester:

A couple of questions please:
What are you powering the drive motor with? And what sort of wire feeder are you using?.....
The whole shabang, Gas shut off toggle switch and plumbing, wire spool and gun with feeder pieces and parts, you hold in your hands. Yep.. two hand welding needed. It's all incased in a platic case and looks like a short old Sci Fi movie ray gun with a heavy wire comming out and a gas hose. It looks even stranger when you attach the drive motor. Yes I'm postivie it is patented. Someone at Readywelder owns the Patent.

The wire drive system in this Readywelder prototype (MIGMASTER) is some gears, a friction wheel that one of the gears turn which presses against the wire and causes it to feed. Oh and there is a post at the end of one of the gears that sticks out of the case. You hook your favorite variable speed drill too this. :eek: TADAAA with that as your drive motor this MIG has finger touch variable wire speeds. One crazy looking contraption.

I assume the friction wheel method used to feed the wire is same way it's done inside the box of a MIG machine. I have looked at the parts inside mine and compared them to on the shelf stuff. I know the tips and several other parts are the same ones used with larger 220v machines. I bet some of the drive parts are off the shelf too. I happen to use a variable speed portable drill with mine.

The drill is billed as a woman's light weight drill. It is set up so you can have the battery seperate like hanging on your belt. My background in biomechanics hinted at me to get a light weight drill for better hand control and no heavy battery on the handle of the drill seemed perfect. Or was that my lazyness telling me that :cool2: I bought it on Amazon for cheap. When I first searched for a drill to go with this welder I searched for 12v ones. I thought I might can actually wire it to the same batteries Im welding with. Since this one already had the battery seperarte I have not taken on that project yet cause this is working fine. Well.. when I have welder batteries working its fine.

I'll try to remember to get pics of the innerds next time I change the wire out.

You might still be able to buy one of the last ones of these from Readywelder. They were selling them for 100buks to get rid of them. Their big seller now (Readywelder II) sells for around 500+ buks. It has it's own wire feed motor and all other kind of bells and whistles.

[Rick V]

Hey George... what's the latest? It's been over a month of silence... and I am really curious to hear the rest of the saga (your epic story):
- did you get your battery powered welder up and running again,
- what you using now for batteries, and
- battery chargers?

Rick V

[MAC702]

...I'd call Pep Boys about paralleling the units. ...
Man, I knew you had a twisted sense of humor. What are you trying to put this guy through? :)

[awright]

Mac, I understand your point.

But even though the chances of getting a useful response, or even talking to someone who knows what the product is, is very small, it NEVER hurts to go to the supplier to ask, especially when it can be done in a couple of minutes while sipping a drink at your computer in your skivvies. Of course, I'm not talking about going down to your local store and talking to the teen-ager behind the counter. Google the headquarters tech support or sales dept. The worst that can happen is you draw a blank and you get the privilege to curse them out. The best is that they respond with a link to the manufacturer who actually knows something about the product and helps you out.

I'm always surprised, for example, that people will ask technical questions here about failures of Miller machines without having even checked with the very good support team at Miller. Good for our egos and entertainment, but not the most effective approach to get the most accurate information. I certainly don't want to cut down on communications here, but my advice is always START with a request to the equipment supplier. Sometimes you will be surprised at the amount of assistance you can get.

I spend xxxxx waste a lot of time repairing and restoring obsolescent mechanical and electronic equipment, and I always start with a search for the manufacturer. Some companies like Keithley are proud of the longevity of their instruments and try to offer support for obsolescent instruments. Unfortunately, many companies buy up competetors, shed all the parts and manuals, and tell you, "Gee. That instrument is eight years old and we dont have any information or parts for it any more."

A positive example of a result you'd never expect: I've had a Logan 9" bench lathe for about 55 years - bought it as an early teen from my neighbor when he was moving to a retirement community. Logan has been out of business for decades, but it turns out that some branch of the Logan family, now in a different business entirely, tries to provide parts left over from the original firm. Nice people. Who'd know it without a search?

awright

[MotoFab]

Shill

http://en.wikipedia.org/wiki/Shill

- Jim