Parallel Inverter Welders - With Pictures!
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  1. #1
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    Parallel Inverter Welders - With Pictures!

    Here's a real Power Up story for y'all. I didn't really expect this to work at that well... but it did fantastically well!

    Here's the story...
    A few years back, I bought a slightly used Canadian Tire 'Mastercraft' brand inverter welder off Kijiji for $200. The attraction for me was that it was a portable 100 amp tig welder and 80 amp arc welder - and it came with the tig torch! Actually this first welder came with $80 worth of extras - to the left off the welder in the picture.
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    A couple months back, I bought an identical unit off Kijiji for $100 plus $30 shipping. It was advertized as an inverter stick welder in an unopened box... but I knew it was a tig welder with torch! Lucky for me that the tig torch was no too visible on the box!

    OK, so I had two identical inverter welders. Here's a photo of the electrical characteristics.
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    On a 120 volt, 20 amp input, the welder can output 80 amps stick at 21 volts or 100 amps tig at 14 volts with a 30% duty cycle. In some previous posts, I had stick welded with the first unit . While it laid down OK looking beads with 3/32 inch electrodes, when it came to fillet welds (sucking more heat away) it was marginal with 6011, 6013 and 7014 but definitely 'cold' with Lincoln 7018AC. In fact I was told to 'get rid of that POS inverter!'

    Yeah, I was looking for a more powerful inverter stick welder and posted on that, "Cheap Inverter Stick Arc Welders - Thoughts?" http://weldingweb.com/showthread.php?t=58082

    A couple of weeks ago, I decided to actually measure the output amps of the first welder using a DC clamp-on meter.
    - I measured a max of 65 amps with a 3/32 inch electrode (7014) and 80 amps on short circuit.
    - I measured a max of 80 amps with 1/8 inch electrode (7014) but that was low amps for that size rod.

    As I had suspected, that's just not enough amps for some 3/32 inch 7018 rods (e.g. Lincoln 7018AC) and most all 1/8 inch rods.

    The idea to try and parallel my two inverter welders came to me yesterday. I thought I would be careful and check with a multimeter that there was no feedback from one to the other. Even if there was no feedback, I felt that maybe the low 21 volt arc voltage might limit the amps to 80 or less anyway - same as one welder.

    So tonight, I tried it... and it worked - Frigging Super!
    1 - Checked with a multimeter - there was no feedback from one to the other welder
    2 - Hooked the welders up in parallel and WOWEEE !!! POWER BABY!!!

    Here's the two welders, side-by-side.
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    Here's me plugging in the two 120 volt, 20 amp plugs from the welders into the duplex 20 amp receptacle.
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    Note: Both sockets are wired to one 12 gauge wire running to a single 20 amp breaker. I popped the 20 amp breaker after running about 1 inch of 1/8 inch 7014 electrode with both welders in parallel. For the final bead runs with 1/8 inch electrode, I changed to a 30 amp breaker - a bit high for #12 wire.

    Here's a photo of the two welder, each amperage knob set to 70 amps. To the left you can see the electrode holder positive leads joined together.
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    To be continued... give me time to post the rest please.
    Rick V

    1 Airco Heliwelder 3A/DDR
    3 CTC 70/90 amp Stick/Tig Inverters in Parallel
    1 Lincoln MIG PAK 15
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  2. #2
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    Re: Parallel Inverter Welders - With Pictures!

    The negative grounds were joined by simply clamping their ground clamps to the welding grill.
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    Here's a photo of the positive electode holders joined to a new stinger cable. For this quick test, each Tweeco-style electode holder was clamped to a small copper bar. The end of the stinger lead was clamped to be copper plate using vice-grip-style pliers.
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    Here's the results of messing around before the slag was knocked off the welds. That steel plate was 3/16 inch thick, 6 inches long and 2 inches wide.
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    Here's the results... YIPPEE... IT WORKED!!!
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    When I tried that first weld with the inverters in parallel, I didn't know what to expect... but the huge change in the 3/32 7014 arc spoke loudly! That 3rd bead on the top row was HOT! Too hot - way wider and flatter than two individual welder beads preceeding it. This could have been of the order of 2 x 65 amps = 130 amps. Yeah, a whole lot of amps for a 3/32 inch electrode!

    I then tried (second row) the same 80 amps settings with a larger 1/8 inch diameter 7014 electode. First two beads for each welder were almost cold but the 3rd bead (parallel welders) was hot! This could have been of the order of 2 x 80 amps = 160 amps. That's quite a bit of amps for a 1/8 inch electrode.

    In row three, I used an 1/8 inch 7014 electrode with the welders in parallel. I ran a series of short beads with the welders both set at 40, 50, 60 and 70 amps. The results look more like I'm getting what:
    - 1.5 x that: 60, 75, 90 and 105 amps? (last bead looks hotter than 105 amps)
    - 1.75 x that: 70, 88, 105 and 123 amps?
    - 2 x that: 80, 100, 120 and 140 amps?

    Anyway, that's the story... it sure was fun!
    Rick V

    1 Airco Heliwelder 3A/DDR
    3 CTC 70/90 amp Stick/Tig Inverters in Parallel
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  3. #3
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    Re: Parallel Inverter Welders - With Pictures!

    IF both welders are plugged into the same circuit, I don't think you'll be exceeding 100 amps or so.
    My name's not Jim....

  4. #4
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    Re: Parallel Inverter Welders - With Pictures!

    Quote Originally Posted by Boostinjdm View Post
    IF both welders are plugged into the same circuit, I don't think you'll be exceeding 100 amps or so.
    Breakered for 30 amps, I thnk it's possible I'm pushing closer to 140 amps.
    e.g.
    Input: 2 welders X 115 volts X 15 amps = 3450 volt-amps
    Output = Input volt-amps x 85% (published efficiency of this welder) = 2932 watts
    Plated arc voltage of 20 volts would yield 2932/20 = 146 amps.

    According to the electrical plate (earlier picture), output could be in the range of 120 to 160 amps
    e.g.
    120 volts @ 15 amps, stick output is 20 arc volts at 60 amps, multiple that current by 2 = 120 amps
    120 volts @ 20 amps, stick output is 21 arc volts at 80 amps, multiple that current by 2 = 160 amps

    Then too there is the feel of the arc while welding and the appearance of the beads. Those right-side beads on 3/16 inch plate with 1/8 inch 7014 sure felt and looked like more than 100 amps. I think I'm getting about 140 amps on the 1/8 inch electrode.

    Ah well, guess I'm just going to have to measure it... then we'll know for certain.
    Rick V

    1 Airco Heliwelder 3A/DDR
    3 CTC 70/90 amp Stick/Tig Inverters in Parallel
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  5. #5
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    Re: Parallel Inverter Welders - With Pictures!

    Try two separate plug circuits instead of the same plug (if you have access to 2 different circuits in the shop area)

    Having a Harbor Freight 80A inverter & a 100A Forney unit I found they weld better using 1/16" rods....maybe 3/32" for heavier max output... anything larger just seemed not to flow well.

    Since you're doubling up though larger rods should be usable. I've often wondered if this could be accomplished since I read of it being done with a couple of Millers somewhere.(guess it can) I've never had 2 identical units to test the idea (or the guts to chance it if I did)

    I'm assuming you're end goal is more juice for Tig welding? That would be interesting too.

    Thanks for the pictures of your test...

    I really like both my "little" inverters and usually use them for little stuff around the shop that needs a quick fix...they're just too easy to grab and weld with. I found a 1930's AC small box welder that puts out 80-100A and bought it because it was cheap & in excellent condition (almost new). It welds as well as the inverters (just AC) but weighs about 45# so it sets on the bench.

    These little inverters are highly underated as far as their abilities are concerned... Enjoy yours and have fun experimenting with the dual output...

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    Re: Parallel Inverter Welders - With Pictures!

    you do some really odd things. Just so you know, you can buy/make a y cable that ties both positives together and has a female connector for you to plug your stinger in. We do it all the time for air-arcing with xmt 304's.
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    Re: Parallel Inverter Welders - With Pictures!

    Quote Originally Posted by mudbugone View Post
    ... I've often wondered if this could be accomplished since I read of it being done with a couple of Millers somewhere.(guess it can) I've never had 2 identical units to test the idea (or the guts to chance it if I did)...
    Yeah I wondered too, a few earlier threads talked about it - but just talk/no action.

    Quote Originally Posted by claymans13 View Post
    you do some really odd things. Just so you know, you can buy/make a y cable that ties both positives together...
    Connectors on this welder appear weird, small bayonet types; I'd consider going that route if I decide to do this parallel thing as routine... now is just testing.

    Ok so I measured the amperage... sort of...
    I used a DC clamp-on ammeter to measure the amperages while welding. For a single welder I ran the ground cable through the clamp-on ammeter. When using both welders in parallel, I ran both ground cables through the clamp-on ammeter. I used a digital camera in movie mode to record the amperges from the face of the meter - as shown in the photo. The camera was on a tripod.
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    Measuring the welding amperage was a pain and I can't trust the results from the clamp-on meter.
    Here's the results... refer to the picture below.

    Test 1 - Using 1/8 inch 7014 electrode+
    Welder #1 set at 80 amps on the dial. Bead A: Measured 35 - 43 amps, average 37 amps
    Welder #2 set at 80 amps on the dial. Bead B: Measured 72 - 85 amps, average 80 amps
    Welders in parallel set at 80 amps. Bead C: Measured average between 115 and 125 amps
    Let's see... 37 + 80 = 117 amps. So that seemed to make sense.

    I was worried about that low output amperage on welder #1 so I readjusted the ground clamps.

    Test 2 - Using 1/8 inch 7014 electrode+
    Welder #1 set at 80 amps on the dial. Beads D & E: Measured 71 - 83 amps, average 72 amps (seems I had a better ground)
    Welder #2 set at 80 amps on the dial. Beads F & G: Measured 69 - 80 amps, average 74 amps
    Welders in parallel set at 80 amps. Bead H: Measured between 79 - 115 amps but reflected arc light caused camera problems - couldn't see the amp readings on the ammeter.

    Repeated... with shroud in place to stop light reflections...
    Welders in parallel set at 80 amps.
    On bead (I), I measured 80 - 100 amps amps, average 85 amps ??
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    This wasn't making any sense. Let's see... 72 + 74 = 146 amps, not 85 amps!
    Clearly there is way more heat (than 80 amps) going into beads H & I than went into beads D, E, F and G also made at about 80 amps - according to the ammeter. WTF?

    I don't know what's going on with the amp readings. One thing is for certain, the welders in parallel are producing a much fiercer arc and are laying down a lot hotter and wider bead than either welder can approach alone.

    Any suggestions?
    Rick V

    1 Airco Heliwelder 3A/DDR
    3 CTC 70/90 amp Stick/Tig Inverters in Parallel
    1 Lincoln MIG PAK 15
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    Re: Parallel Inverter Welders - With Pictures!

    if you are on 1 30 amp circuit you probably don't have enough input power which is limiting your output power. When i had my 110v mig, I could VERY clearly tell a difference in peak power on a 15amp vs 20amp circuit.
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    Re: Parallel Inverter Welders - With Pictures!

    Ah-Ha! I found the problem... in Test 2 the jaws of the clamp-on ammeter had opened about 1/8 inch with the two ground cables passing through - that's why the low amperage readings when running in parallel.
    A further test will be needed to confirm that but based upon the simple amp addition results of Test 1, it appears the individual welder delivered amperages just add together. That would mean welds H and I were made with about 72 + 74 = ~146 amps... and the welds look it.
    Rick V

    1 Airco Heliwelder 3A/DDR
    3 CTC 70/90 amp Stick/Tig Inverters in Parallel
    1 Lincoln MIG PAK 15
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    Re: Parallel Inverter Welders - With Pictures!

    You should break the connection tab between the top and bottom outlet and run some 12/3 cable to it for a hot,hot, shared neutral, and shared ground to a dual 20a breaker. This way a single breaker cuts all power into the outlet box, but you do get 40 amps total. Shared neutral is allowed as it will never carry more than one leg of power. IE, when both units are running full out, neutral will have no current through it.
    Running a 30 amp on 12 guage wire is like you said, a bit much.
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    Re: Parallel Inverter Welders - With Pictures!

    Quote Originally Posted by claymans13 View Post
    if you are on 1 30 amp circuit you probably don't have enough input power which is limiting your output power...
    Hmmm, I haven't tripped the 30 amp breaker yet. Maybe I should run a full electrode! Hey, I'm just trying this out.

    Quote Originally Posted by jdchmiel View Post
    You should break the connection tab between the top and bottom outlet and run some 12/3 cable to it for a hot,hot, shared neutral, and shared ground to a dual 20a breaker.... Running a 30 amp on 12 guage wire is like you said, a bit much.
    Yeah but this is just an initial test... a few try outs - nothing locked in stone yet.
    If I decide this paralleling of two 117 volt inverters is what I want to do for routine welding then I would consider some possible wiring changes and lead changes.

    This parallel method has some advantages for me as I already own the two 117 volt welders. I also own two 30 meter (100 ft) long #12 extension cords and these are cheap at Costco... ~$35 each. Further, it's usually simple to find two easily accessible 115 volt 15 amps outlets in any house (or 4,000 watt+ generator) to plug the extensions cords into... and away we go! Beats moving a dryer or a fridge... and no more heavy, expensive #8 or #10 cords and those $15 welder plugs!!! Each inverter welder is quite light and being separate - easy to transport... no welding cart with 10 inch pneumatic rough-terrain tires required.

    Gotto confirm that amperage addition operation then it will be time to leave the beads behind and move onto making some real metal-joining welds. So far this has been a lot of fun!
    Rick V

    1 Airco Heliwelder 3A/DDR
    3 CTC 70/90 amp Stick/Tig Inverters in Parallel
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    Re: Parallel Inverter Welders - With Pictures!

    I'm not an expert on inverter welders but I would think putting them on different phases with double pole breaker may be a problem. I would keep them on the same phase by skipping a slot in the breaker panel and then using 2 20amp breakers and 12 gauge wire to feed circuit.

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    Re: Parallel Inverter Welders - With Pictures!

    transformerr machines in AC mode might end up with issues, but an inverter by design will have no issue.
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    Re: Parallel Inverter Welders - With Pictures!

    Some more testing results...
    Test #3 used a large 3/16 inch thick plate and 1/8 electrodes 7014+ and 6013+.
    The ground clamps cleaned with a wire brush and clamped to the welding grill via a copper block. Both ground leads passed through the ammeter C-clamp and were left there with no gap visible on the C-clamp jaws. Welders were turned on or off as required.
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    1/8 inch 7014+
    Welder 1: 72 - 90 amps, average 76 amps
    Welder 2: 78 - 95 amps, average 86 amps
    Parallel welders (each set at 80 amps): 125 - 158 amps, average 135 amps falling slowly to 115 amps while welding. The decreasing amperage was real - observed two times. Maybe that's the #12 wire heating up with 30 amps?
    Let's see:
    Separate welders = 76 + 86 = 162 amps; that's greater than the parallel output of say 125 amps.
    The average output of the separate welders = (76 + 86)/2 = 81 amps
    The increase in parallel welder current is about = 125/81 = 1.54X

    1/8 inch 6013+
    Welder #1: 88 - 102 amps, average 88 - 95 amps or say 90 amps
    Welder #2: 88 - 102 amps, average 95 amps
    Parallel welders: 132 - 148 amps, average 135 - 145 amps, say 140 amps
    Let's see:
    Separate welders = 90 + 95 = 185 amps; that's greater than the parallel output of say 140 amps.
    The average output of the separate welders = (90 + 95)/2 = 92.5 amps
    The increase in parallel welder current is about = 140/92.5 = 1.51X

    I'm not sure why the parallel current is not just the simple sum of the output of each individual welder. Maybe the current draw is heating up the #12 current supply wires and dropping the input voltage?
    Input current draw = (output watts / efficiency factor) / input voltage
    Input current draw = (140 amps x 21 volts / 0.85) / 117 volts = 29.5 amps

    I'm not certain what happens when you push 30 amps through #12 wire. As already suggested, I should try separate 15 amp circuits and see if I observe that falling welding current after welding for a few seconds.

    OK, paralleling inverter welders to get more welding current works for me!
    For the future, I could use some refinements to my input power wiring and to my welding output leads.

    Thanks for listening and for the great suggestions...
    Rick V

    1 Airco Heliwelder 3A/DDR
    3 CTC 70/90 amp Stick/Tig Inverters in Parallel
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    Re: Parallel Inverter Welders - With Pictures!

    Interesting post- I, too, thought that the power might be voltage-limited but apparently not!

    Those bayonet connectors are called 25mm Dinse connectors. Lenco ( www.profaxlenco.com ) makes male and female connectors which you can use to rig up your adapters. Should be available at your LWS.

    John
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    Re: Parallel Inverter Welders - With Pictures!

    Quote Originally Posted by Silicon-based View Post
    Interesting post- I, too, thought that the power might be voltage-limited but apparently not!
    Yep, I wondered about that at the beginning... but "apparently not!"

    Quote Originally Posted by Silicon-based View Post
    Those bayonet connectors are called 25mm Dinse connectors. Lenco ( www.profaxlenco.com ) makes male and female connectors which you can use to rig up your adapters. Should be available at your LWS...
    Yeah, it all looks good... if living in the USA, $25 at Welding Depot, $25 would get me 4 Dinse males size 10-25 and two (male/female) Lenco cable connectors. Alas, being Canadian, I will have to scrouge around!

    Set both welders at 70 amps on their dials and ran a couple of fillet welds on 3/16 inch plates using 1/8 7014+.
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    Except for my welding errors (slag hole, vertical plate undercut and a little too fast travel speed), the electrodes ran well with something of the order of 110 - 125 amps from the two inverters in parallel.
    Rick V

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    Re: Parallel Inverter Welders - With Pictures!

    Bravo!

    Proof this works is very cool.

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    Re: Parallel Inverter Welders - With Pictures!

    Quote Originally Posted by farmall View Post
    Bravo! Proof this works is very cool.
    Thanks farmall...

    Just to finish up...
    Separate Outlets
    I was running both welders off of one #12 gauge circuit with a 30 amp breaker.
    I changed to two separate 20 amp circuits, each with #12 wires and a 20 amp breaker.

    First I tried 120 volt circuits of the same phase (0 volts between the receptacle short slots (black wires); there was no feedback between the welders.
    Then I tried circuits of the opposite phase (240 volts between the receptacle short slots (black wires); there was no feedback between the welders.
    Good News - Input 120 VAC Phase Difference doesn't matter.

    Amperage Tests (Opposite Phase) with 1/8 inch electrode 6013+
    Welder #1: 64 - 86 amps, average 76 - 83 amps, say 80 amps
    Welder #2: 75 - 105 amps, average 80 - 95 amps, say 85 amps
    Parallel welders: 122 - 157 amps, average avearge 140 amps; 2nd bead: 130 - 172, ave 150 amps
    Let's see:
    Separate welders = 80 + 85 = 165 amps; that's greater than the parallel output of say 145 amps.
    The average output of the separate welders = (80 + 85)/2 = 82.5 amps
    The increase in parallel welder current is about = 145/82.5 = 1.75X

    Amperage Test (Same Phase) with 1/8 inch electrode 6013+
    Welder #1: 64 - 91 amps, average 80 - 92 amps, say 85 amps
    2nd bead: 79 - 99 amps, average 85 - 95 amps, say 90 amps
    Welder #2: 97 - 103, ave 90 amps; 2nd bead: ave say 85 amps
    Parallel welders: 135 - 157 amps, average avearge 143 amps
    Let's see:
    Separate welders = 85 + 85 = 170 amps; that's greater than the parallel output of say 143 amps.
    The average output of the separate welders = (85 + 85)/2 = 85 amps
    The increase in parallel welder current is about = 143/85 = 1.68X

    Given separate 120 volt feeds the welders' parallel output did increase somewhat - not a lot (13%).
    In my case, paralleling my identical welders yielded an increase in amperage of about 1,75X.
    e.g. 80 amps max dial setting on each welder delivered 140 amps parallel output; an increase factor of 1.75X.

    This is great for me!
    Alone, with just 80 amps output on stick mode, each welder was not really 'hot' enough to capable of making conisistently good welds with 3/32 inch electrodes. Doubled up, the welders can ouput 140 amps and that is 'hot' enough to make good welds with 1/8 inch electrodes.
    Yipee!
    Rick V

    1 Airco Heliwelder 3A/DDR
    3 CTC 70/90 amp Stick/Tig Inverters in Parallel
    1 Lincoln MIG PAK 15
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    Re: Parallel Inverter Welders - With Pictures!

    Great research and results as well as your additional information on this in great detail. I've often wondered how this would actually work.

    As you stated earlier you could use this for additional power capacity without a 220v outlet. I'm sure there are those that don't have a 220v line that might actually use your information. You fell into a chance to try this since you purchased 2 identicle welders for cheap. I might give this a go if I find another 80A inverter from HF for some extra power.

    Thanks for taking the journey into the unknown and more importantly for taking the time to share the outcome with all of us.

    What do you imagine the results might be should you use this for Tig welding ?
    Last edited by mudbugone; 12-21-2011 at 11:15 PM.

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    Re: Parallel Inverter Welders - With Pictures!

    Quote Originally Posted by mudbugone View Post
    ... What do you imagine the results might be should you use this for Tig welding ?
    Not having an argon cylinder, I can't do, only guess.
    I would expect a similar result, 1.75 x 100 amps Tig max amperage = 175 amps on Tig.
    However would create a problem as the Tig torches that came with the welders are designed for 100 amps - guess I'd have to upgrade to a 200 amp torch... then time to consider water cooling.

    I'm more interested in knowing what would happen if I could parallel three of these welders? Paralleling two gave me 87.5% of the total seperate outputs, as in:
    (80 + 80) x 0.875 = 140 amps.
    What would adding a third welder give me?
    87.5% of 87.5% of the total separate outouts? (80 + 80 + 80) x 0.875 x 0,875 = 184 amps on stick, or
    maybe (100 + 100 + 100) x 0.875 x 0,875 = 230 amps on Tig ???

    Anyway, the successful combo of the two welders has opened a new world for me.
    I've now got some decisions to make as regards keeping my big-box, heavy transformer welders (Linde 250 AC/DC and Lincoln AC/DC 225/125) that run on 230 volts. Seems to be no point now in keeping both big-box welders.

    At efficiencies of about 55% compared to the inverters at 85%, the whole electrical input situation needs a review. e.g.
    • 50 amp double breaker versus two 20 amp single breakers.
    • From the breaker panel: single run of #6 wires (not in yet and would need a pony panel) versus two runs of #12 wires that already exist.
    • Welder extension cords: 50 ft of #8 gauge ($100 on sale) versus two 50 ft #12 gauge (total ~$40). The 230 volt plugs and sockets are expensive at $15+ per versus $4 per unit.

    The paralleled welders have not drawn more that 30 amps total - that's 15 amps per 120 volt wall receptacle... commonly available most anywhere in North America. Called over to a friends house or job site, armed with two 100 ft #12 gauge cords, I'd be good-to-go. In comparison, lugging 100 ft of #8 gauge and moving a dryer or stove seems a pain.

    This dual 120 volt welder approach seems an advantage too over a single 240 volt inverter welder of the same capability. While such a single inverter welder might draw only 15 amps at 230 volts, I'd still be stuck with that 230 volt requirement.

    Yeah, for me, this makes it a whole new game .
    Rick V

    1 Airco Heliwelder 3A/DDR
    3 CTC 70/90 amp Stick/Tig Inverters in Parallel
    1 Lincoln MIG PAK 15
    1 Oxy-Acet

  21. #21
    Join Date
    Jan 2006
    Location
    Ottawa, Ontario, Canada
    Posts
    2,485

    Re: Parallel Inverter Welders - With Pictures!

    Ooops, one more interesting & rather weird effect I forgot to mention.
    When the welders are paralleled the arc 'sings'!

    Yeah weird or what! I kept wondering if something was wrong.
    I noticed that the singing became noteably louder the longer the arc.

    The explanation came to me this morning...
    Each of these inverter welders operates at high frequency above the audible range; something like 18,000 Hz+, way above the transformer-based welder's 60 Hz. Operating a singel inverter welder, you can't hear this... it might drive your dog nuts though.

    When you operate two such welders in parallel, they are both driving a common arc, each pulsing at it's own internal frequency, say f1 and f2, which are close but not exactly the same. This creates a beating sound - like you hear when two of more engines are running together but at slightly different speeds. You get a throbbing sound superimposed on the normal engine noise. e.g. Twin or four engine propellor driven aircraft

    I hear this type of throbbing sound when I operate my my small air compressors together; if I run all 4 of them it sounds like a bloodly four-engine bomber! Thrum-thrum-thrum-thrum....

    What's happening is called hetrodyning... you get the sum and difference of the frequencies.
    e.g. f1 + f2 and f1 - f2. Suppose my welder frequencies are f1 = 18,000 Hz and f2 = 18, 800. The sum of the frequencis is 36,800 Hz - way above the audible range so you can hear that. However, the difference of the frequencies is 800 Hz and you can definetly hear that!

    What started out as annoying is actually helpful. The shorter the arc, the quieter is the 'singing'. So now I have two feedback mechanisms - the visible length of the arc and the loudness of the singing! Keep the sound down (short arc) and I get a good weld.

    Maybe 'Darth Welder' should become the the 'Singing Arc'.
    Rick V

    1 Airco Heliwelder 3A/DDR
    3 CTC 70/90 amp Stick/Tig Inverters in Parallel
    1 Lincoln MIG PAK 15
    1 Oxy-Acet

  22. #22
    Join Date
    Jun 2010
    Location
    raleigh nc
    Posts
    371

    Re: Parallel Inverter Welders - With Pictures!

    interesting!
    BTW, i bet teh reason you do not get 2x the current ( ie 80 + 80 = 160 ) is the voltage is not changed at all, so that is just the max current that will flow at that voltage with whatever load is created by your two cables, clamp / rod holder and rod / arc. I bet you could get more current out if you upgraded wires to higher gauge, used good clamp / holders, and had good solid connections.. but do you need more ? is it worthwhile? Maybe a bigger Rod would flow more as the steel in the rod is the biggest resistor in your circuit.
    miller syncrowave 250
    hobart handler 140
    home made 400 amp engine driven in progress...

  23. #23
    Join Date
    Jan 2006
    Location
    Ottawa, Ontario, Canada
    Posts
    2,485

    Re: Parallel Inverter Welders - With Pictures!

    Quote Originally Posted by jdchmiel View Post
    interesting!
    BTW, i bet teh reason you do not get 2x the current ( ie 80 + 80 = 160 ) is the voltage is not changed at all, so that is just the max current that will flow at that voltage with whatever load is created by your two cables, clamp / rod holder and rod / arc. I bet you could get more current out if you upgraded wires to higher gauge, used good clamp / holders, and had good solid connections.. but do you need more ? is it worthwhile? Maybe a bigger Rod would flow more as the steel in the rod is the biggest resistor in your circuit.
    Yep, the voltage is supposedly fixed at 21 volts. I think you are right! At some point increasing the available amps is not going to increase the arc current because, as you say, the resistance of the rod/arc/clamps and cables has not changed. I did notice that my 1/8 inch 6013 rods flowed about 10 more amps that my 1/8 7014 rods.

    I'm all set now to rewire the output - changing from two 8 ft lengths of #6 cable going to 2 ground clamps of dubious quality. I just received 4 new Dinse 10-75 connectors. My plan is to use #4 cable to make the short (1 ft) V of the Y connection to 15 ft of #2 cable ending with a really good steel/bronze contact ground clamp. Same again for the stinger: 1 ft Y of #4 to 20 ft of #2 going to the electrode holder (Bernard or Tweeco - have both).

    I'm also set to rewire the inputs. I have to make up two short connectors: 15 amp plug to 20 amp socket. Those will allow me to plug the welders into any two standard extension cords. I do have two, 100 ft #12/3 supe-flex extension cords - but a mite long for the garage! So today I bought another 100 ft cord ($40 at Costco) that I intend to cut into shorter cords: 2 - 22 ft, 2 - 16 ft and 2 - 12 ft. I have lots of quality plugs and sockets to terminate the #12 cords.

    So yeah, I should be wringing the maximum amps that I can from the new set up.
    Still, until I move to a larger diameter rod, like 5/32, I don't expect much increase over the 140 amps I've already seen. However, the pluging in set up will be far more convenient and less dependant upon so many ' iffy' temporary metal to metal contacts.
    Rick V

    1 Airco Heliwelder 3A/DDR
    3 CTC 70/90 amp Stick/Tig Inverters in Parallel
    1 Lincoln MIG PAK 15
    1 Oxy-Acet

  24. #24
    Join Date
    Jan 2006
    Location
    Ottawa, Ontario, Canada
    Posts
    2,485

    Re: Parallel Inverter Welders - With Pictures!

    UPDATE...
    I rewired the welder inputs using 16 foot #12 gauge extension cords. I plug each extension cord into a separate 20 amp breakered wall outlet. I plug each welder into it's extension cord using a short 6 inch long 15 amp plug to 20 amp socket.

    I changed out the welder cables. Originally each welder used a total of 16.5 ft (9.5 electrode and 7 ft ground) of #7 gauge cable. Each #7 cable was carrying a maximum of 70 to 80 amps. I wanted to increase the ampacity.
    • From each welder's + connector, I used 1 ft of #4 red cable joining to a 'T' to 10 ft of #1 gauge cable going to the electrode holder.
    • From each welder's - connector, I used 1 ft of #4 black cable joining to a 'T' to 10 ft of #1 gauge cable going to the ground clamp.

    The first picture shows the brass 'T' air fitting I used to join the cables from the two welders: drilled, tapped for 3/8 inch NC, stainless steel set screws used to secure red/orange #4 cables and #1 black cable. I used thin brass sleeves inside the fitting so as not to cut the copper stands on the fitting threads.
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    The second picture shows the completed fittings wrapped with insulating electrical tape. Also shown is the electrode holder and ground clamp I chose to use. The ground clamp is interesting as it uses bronze conductors (joined with copper braid) inside a steel camp. Sort of the best of both worlds: bronze for electrical conduction but encased in steel to prevent breaking the bronze should the clamp get dropped, etc.
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    The third picture shows the average welding amps (140 - 145) and maximum amps (~170) welding amps recorded by the video camera while welding. Both welders were set at max amps - 80 amps on each dial.
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    Shown is the result using 1/8 inch 6013 electrode + at an average of 145 amps. Normal amperage variation was 140 - 150 amps. 1/8 inch electrode ran smooth and nice = very good.

    Also shown is the result using 5/32 inch 7014 electrode + at an average of 145 amps. Normal amperage variation was similar, 140 - 150 amps. This larger 5/32 inch electrode was too much metal for the paralleled welders. I struck the rod several times on starting. It was difficult to maintain the arc - I could not maintain a normal arc length without the arc going out. I had to use a very short arc. Still the weld bead, particularly the first few inches (left side) went down well enough. However, I felt I didn't have enough arc volts to run this 5/32 electrode.

    On the other hand, I don't think my Lincoln AC/DC 225/125 could run this large size electrode on DC either... 125 amps would not be enough.

    Overall, I'm quite pleased this paralleling welders worked so well.
    Alone, each 80 amp inverter welder was good for 65 amps max with 3/32 inch electrodes - just enough amps for 6011, 6013 and 7014 but really not enough for 7018. With 1/8 inch 7014, I could get the max 80 amps out of each welder but that 80 amps was too low to run most any 1/8 inch electrode (OK, maybe 6010/6011).

    Paralleled together, the welders could run all 3/32 and 1/8 inch electrodes that I had. I could even get a marginal result with 5/32 7018.
    That was/is a major improvement in cabability...

    I question keeping my two remaining big box transformer welders? If I stay with 1/8 inch or less diameter electrodes, the paralleled inverters are more convenient to set up and use... anywhere.

    Yeah, this worked out GREAT!
    Rick V

    1 Airco Heliwelder 3A/DDR
    3 CTC 70/90 amp Stick/Tig Inverters in Parallel
    1 Lincoln MIG PAK 15
    1 Oxy-Acet

  25. #25
    Join Date
    Jul 2009
    Location
    O.C. CA
    Posts
    772

    Re: Parallel Inverter Welders - With Pictures!

    I would get rid of the big trannies and look at getting rid of the little inverters also. I would see about getting the TA 161stl since they are on sale at cyberweld right now. As always your very thorough with your post but the one thing I see you don't address are the volts of the output the machines run at. Yes they are cc machines but the TA unit runs at 26.4v vs the 21v of your units. The extra volts will let you run 5/32" 7018 rod. I don't the TA 161stl but I do have the TA 185 which has the same stick welding output and don't have any problems running 5/32" 7018.

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