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Generator Size Issue - How Much Wattage?

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  • Generator Size Issue - How Much Wattage?

    I have a Generac XP4000 generator that is rated at 20 amps output on 120v and just a tad more on 240v.

    Assuming that I wouldn't need to run a welder at high amperage output for the light welding that I do around the house, I bought a Millermatic 211 welder that is rated at 20 amp input.

    The Generac generator has an electronic speed sensor and a circuit board that controls the throttle according to load. About four out of five times that I pull the trigger on the welder, the generator fails to throttle up and dies down until I release the trigger. After several tries, the generator will throttle up like it should and I can continue to weld. Needless to say, it makes for nasty looking welds and a frustrating experience.

    Here is my problem. I tried to get the generator repaired under warranty, but the manufacturer says the welder is drawing more power than the generator can supply, and I need at least a 8000 watt version. The welder voltage is set at 6, and I am only welding 1/8" steel. I would think that this should be well under the 20 amp output that the generator is rated at. In fact, I would think it should only be pulling about 60% of the 20 amps.

    Am I missing something, or would the welder somehow pull enough amperage to choke down the generator, even at the 6 setting? Since it seems to work fine about every fifth pull of the trigger, I just believe that the manufacturer is off base with their claim that the generator is undersized.

    What are the thoughts of you guys that do this all the time?

    Thanks,
    Bill

  • #2
    Generator Size Issue - How Much Wattage?

    The output on the generator at 120v is around 30amps and only 15amps for 240v. Try using the welder with the 120v plug. I have the Generac 10k generator, it has a switch to turn off the idle down mode and keeps the RPMs up all the time. I believe yours should have a switch on the panel to disable the idle control.

    Comment


    • #3
      You need to look at total WATTS not AMPS. You could have a 500 watt or a 10,000 watt generator and still only have a 20 amp crcuit.
      Your welder, when running on 120 volts- 20 amp input, is only rated @ 90 amps and 20% duty cycle output. On setting 6 you may be exceeding that (?).
      Most generators are rated at peak output and don't produce that rating continuously. It's very likely that a 4000 watt generator is too small to do what your trying to do, and even with a properly sized generator if the idle control is kicking in and out it's going to give you fits and could likely screw up the electronics in the welder due to the voltage fluctuations.

      Comment


      • #4
        Generator For 211.

        I run my MM211 with this.
        MillerMatic 211 Auto-set w/MVP
        Just For Home Projects.

        Comment


        • #5
          It appears that you do have an idle control as Labmaster mentioned so turn it off so it doesn't idle down.

          Just because the receptacle has a 20 amp rating doesn't mean it actually supplies 20 amps- it is rated up to 20amps.

          4500 watt genset/240 = 18.75 amps MAX to the 5-20r and L14-20 receptacles.

          So when you have 120v/240v toggle switch in the 240v mode it supplies Half of the total wattage to the 5-20 receptacles and to the L14-20 240v.

          if you need more amperage capacity at 120v then you need to set the Toggle switch to 120v and use the L5-30r.

          Of course for now just turn the Auto Idle control off and try it again on the regular 120v receptacles
          Ed Conley
          http://www.screamingbroccoli.net/
          MM252
          MM211
          Passport Plus w/Spool Gun
          TA185
          Miller 125c Plasma 120v
          O/A set
          SO 2020 Bender
          You can call me Bacchus

          Comment


          • #6
            No Idle or Toggle Switch

            Originally posted by Broccoli1 View Post
            It appears that you do have an idle control as Labmaster mentioned so turn it off so it doesn't idle down.

            Just because the receptacle has a 20 amp rating doesn't mean it actually supplies 20 amps- it is rated up to 20amps.

            4500 watt genset/240 = 18.75 amps MAX to the 5-20r and L14-20 receptacles.

            So when you have 120v/240v toggle switch in the 240v mode it supplies Half of the total wattage to the 5-20 receptacles and to the L14-20 240v.

            if you need more amperage capacity at 120v then you need to set the Toggle switch to 120v and use the L5-30r.

            Of course for now just turn the Auto Idle control off and try it again on the regular 120v receptacles
            I'm not sure why, but my model (XP4000) does not have the Auto Idle Off Switch, nor does it have a toggle for 120/240. It just has two banks of 120v plugs, and a 240v plug that will supply either voltage that you require. I actually was using it on 120v because the 240v plug that came with the welder does not plug into the generator. Since voltage is pressure, I was wondering if the welder might be more efficient on 240v? If so, I can wire up a new plug and try it out. Doughboyracer's reply was intriguing too. He's running the same welder on a Honda 3000 watt generator. It's specs says it supplies 25amps though. By the way, thanks for all the replies everyone.
            Last edited by jacketfan; 09-05-2012, 07:49 PM.

            Comment


            • #7
              The Honda 3000 has Eco Mode
              Which is the their idle control and it will
              Bog down with it on also.

              The mm211 will bog down my Honda 6500eu
              If I have the Eco On.
              Ed Conley
              http://www.screamingbroccoli.net/
              MM252
              MM211
              Passport Plus w/Spool Gun
              TA185
              Miller 125c Plasma 120v
              O/A set
              SO 2020 Bender
              You can call me Bacchus

              Comment


              • #8
                I had a 7000 continuous watt generator from Costco. I thought it worked ok until I got my Trailblazer. The same welder plugged into the Trailblazer works so much better. The 7000 watt generator just didn't put out enough power. (Even on the 30 amp side)

                I was able to return it to Costco due to a recall on the carburetor.
                Lincoln Vantage 400
                Trailblazer® 302 Air Pak™

                Miller Dynasty® 350
                Millermatic 350P Aluminum
                Millermatic® 252
                Syncrowave 351
                Lincoln LN-25 Pro

                Multimatic™ 200

                XR-Aluma Pro Gun
                Diversion™ 180

                Spectrum® 625 X-TREME™

                Thermal Dynamics® Cutmaster® 52
                Victor Oxy/Acetylene Set

                Comment


                • #9
                  if the only problem your having is the generator not idoling up just plus a small low wattage bulb into one of the outlets that will make the generator stay idled up. use the smallest wattage bulb you can find or anything you can find to plug into the outlet a small radio might work also as long as the generator has a curent being pulled out it should stay idled up . i did this with my 5000 watt john deere when i would run my small mig box off it and it worked like a charm.

                  Comment


                  • #10
                    Follow-Up Info

                    Originally posted by jacketfan View Post
                    I have a Generac XP4000 generator that is rated at 20 amps output on 120v and just a tad more on 240v.

                    Assuming that I wouldn't need to run a welder at high amperage output for the light welding that I do around the house, I bought a Millermatic 211 welder that is rated at 20 amp input.

                    The Generac generator has an electronic speed sensor and a circuit board that controls the throttle according to load. About four out of five times that I pull the trigger on the welder, the generator fails to throttle up and dies down until I release the trigger. After several tries, the generator will throttle up like it should and I can continue to weld. Needless to say, it makes for nasty looking welds and a frustrating experience.

                    Here is my problem. I tried to get the generator repaired under warranty, but the manufacturer says the welder is drawing more power than the generator can supply, and I need at least a 8000 watt version. The welder voltage is set at 6, and I am only welding 1/8" steel. I would think that this should be well under the 20 amp output that the generator is rated at. In fact, I would think it should only be pulling about 60% of the 20 amps.

                    Am I missing something, or would the welder somehow pull enough amperage to choke down the generator, even at the 6 setting? Since it seems to work fine about every fifth pull of the trigger, I just believe that the manufacturer is off base with their claim that the generator is undersized.

                    What are the thoughts of you guys that do this all the time?

                    Thanks,
                    Bill
                    Thanks to all for your valuable input. I wanted to fill you in on my findings, and maybe it will help somebody. First, my Generac XP4000, Model 5604 does not have the variable idle feature. I thought I was getting that, but it turns out that some Model 5604's have it, and some don't. How did that happen.....I don't know.

                    After getting the generator back from the repair shop, I checked the amperage pull when plugged in to 120v with the wire feed set to 45 and the voltage set to 6. It spiked to 25 on startup, and settled in at 20, which is the rated output on that generator circuit.

                    Just for kicks, I plugged it into the wall where it could get all it wanted and it pulled a steady 26-27 amps. That tells me the welder needs more than the generator, rated at 20, could provide. Curious, I plugged the welder into the 240v side of the generator thinking it would pull half the amperage off each 120v gen circuit. It still bogged it down, but I couldn't get an amperage reading on the individual 120v wires. Bottom line appears to be that this generator is just not capable of powering this welder. Sure hope this helps someone who might get in the same situation.

                    Comment

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