Miller Electric

Welding Discussion Forums

Home » Resources » Communities » Welding Discussion Forums

  • If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Announcement

Announcement Module
Collapse
No announcement yet.

Generator Question

Page Title Module
Move Remove Collapse
X
Conversation Detail Module
Collapse
  • Filter
  • Time
  • Show
Clear All
new posts

  • Generator Question

    I have a Coleman 5000 watt generator that I use occasionally. The salesman at a local lawn and garden equipment sales store told me that my generator will only put out 1/2 of it's claimed output after running for thirty minutes. Is this true or is he just trying to sell me a new generator?
    Thanks,
    Nick

  • #2
    Did he load test it, to come up with that conclusion? Sounds like he's working on commission, and needs sales.

    Comment


    • #3
      Never heard of that before- maybe he misread the specs about fuel consumption

      "Runs up to 11 hours @ 50% load"

      Comment


      • #4
        I've heard of this before, it's called crapola.......something to do with science

        Comment


        • #5
          Most generators such as the Coleman Powermate that you have, have a Max Load and Continuous Load. Also, if you are wanting to get the most Fuel Efficient and longest run time, there is another load, generally around 50% of Rated Continuous Load.

          The Max Load, generally related to Inrush Current and Max Amp Draw of the load being run, is listed for a short time interval, such as the 30 Minutes mentioned by the lawn equipment guy. The Continuous Load is generally the load that can be sustained for an extended period of time. However, for MAX RUN TIME, it is generally recommended to only run at 50% of Rated Continuous Load.

          An Example I have seen, 5000 Watt Generator. Max (Peak) Load (30 Minutes) 5500 to 6250 Watts, depending on the power windings. Max Continuous Load, 4000 to 5000 Watts, depending on windings. Max Run Time Load, 2000 to 2500 Watts, also depending on winding.

          For what your generator is actually rated at, consult the Owners Manual or the Manufacturers Website for your particular model. But it also sounds like the sales guy, doesn't know what he is talking about.

          At an ARRL Field Day event I helped run with an Amateur Radio Club in central TX, we ran the 4 transmitter setup and associated fans, power supplies, lights, and other comforts we needed off of a Miller Big 40 Rental Generator/Welder. It had a 10 Gallon Diesel Tank and we did put 5 Gallons of Diesel in the unit during the night. For the 24 Hour event, it did run 23 hours before shutting down because of low fuel. Had the welder had be setting level and not on the slope it was on, it would have made the full 24 hours. It had no load on it at all, probably about 1800W max on the 120V plugs.

          Comment


          • #6
            The saleman actually said that the Honda generators loose about 10% after thirty minutes and the Coleman looses 50% after thirty minutes. Without trying to sound biased, they are a Honda dealer.

            Comment


            • #7
              Tell him to show you proof. I have an old 4000 watt Coleman that I initially bought to hook to an old buzzbox to weld with. I can tell you that it ran near at or over rating for well over 30 minutes. Ask the guy why this is the case.

              Max Continuous rating is just what it say Max Continuous, it should run at those watts until it doesn't run any longer. Generators are just like any other mechanical thing, run them at redline and they won't last quite as long.

              Comment


              • #8
                We design and build larger generators. 20 - 150 kW models. The basic principles are the same though.

                You sales man is correct. I do not know the specs on the Coleman's engine, however ALL power units have two ratings. Continuous and Standby (intermittent). For various reasons that would take a book to explain, engines cannot run forever at a given horsepower. A Corvette may have "550 hp" but that is basically an intermitent load. If you were were to evaluate it on a "continous" basis it would be MUCH less. Perhaps 200 hp. Gasoline engines lose alot more horsepower between intermittent duty and continous duty compared to a diesel.

                Since your generator is engine driven, it has a subsequent Prime and Standby rating. Normally, prime is about 75%-85% of standby rating. This is basically the same reason welders have duty cycles. When Coleman and most other people advertise or rate their gensets, they almost always give you the higher kW rating (standby) because it sounds like you are getting more for your money.

                You also should consider what you will be running with the genset. If you will be running electric motors alot as opposed to lights, etc, I would recommend buying up to 50% more kW than you think you will need. Motors take more wattage than they are rated for during hte startup and if you dont have the wattage, you will burn up starter windings in the electric motors. Another thing is that ideally, you want to run your generator around 75% of capacity for longer life.

                I know this is an old thread but thought I would pipe in my 2 cents.
                Last edited by ChiliDog; 11-02-2008, 10:39 AM.

                Comment


                • #9
                  You sales man is correct. I do not know the specs on the Coleman's engine, however ALL power units have two ratings. Continuous and Standby (intermittent). For various reasons that would take a book to explain, engines cannot run forever at a given horsepower. A Corvette may have "550 hp" but that is basically an intermitent load. If you were were to evaluate it on a "continous" basis it would be MUCH less. Perhaps 200 hp. Gasoline engines lose alot more horsepower between intermittent duty and continous duty compared to a diesel.

                  Since your generator is engine driven, it has a subsequent Prime and Standby rating. Normally, prime is about 75%-85% of standby rating. This is basically the same reason welders have duty cycles. When Coleman and most other people advertise or rate their gensets, they almost always give you the higher kW rating (standby) because it sounds like you are getting more for your money.
                  Fill me in here tho. What you describe isn't so much of an 'ouput' issue as it is an 'engine life' issue. From what I'm getting here is that the engine isn't designed for extended full load duty, not that the genset will start putting out less, ie shortened life expectancy of the engine and not reduced output??

                  I visualize full load for whatever length of time I choose to demand it until 1) the engine pukes whether that's three hours or three years, 2) some thermal device on the engine shuts it down, 3) some thermal device on the generator/alternator shuts things down. What I can't visualize is reduced output after thirty minutes.

                  Sounds to me like either a misunderstanding on the salesmens part or, still, a marketing style play on words??

                  Comment


                  • #10
                    It is poor wording by the sales dood.

                    This from my Honda EU200i genset

                    " Limit operation requiring maximum power to 30 minutes. Maximum power is 2,000va"

                    " For continuous operation, do not exceed the rated power. Rated power is 1,600 va"
                    Last edited by Broccoli1; 11-02-2008, 01:24 PM.

                    Comment


                    • #11
                      I have neveer heard what you were told before, and i wouldn't believe it without seeing proof on some testing equipment or from lab tests that have been published

                      My coleman Blackmax (13hp 6500w continuous - 8450 peak actually the RMS rating i was surprised to learn) has about 25 - 30 hours on it and still powers my dynasty 200dx all the way to the max amp output without even sounding too different than running a grinder off of it. I've run some real long beads on genny power. Even using high frequencies in the 160 - 200hz at 200 Amps the coleman held it's ground. The very last time i used it I was TIG'ing aluminum and burned some stick at high amps (Cut/Blasting Rod, 7018, 6013, & 6011) just to see what it would do and it ran as goos as it did the day i got it and the generator never even flinched.
                      Last edited by turboglenn; 11-02-2008, 02:36 PM.

                      Comment


                      • #12
                        Originally posted by Broccoli1 View Post
                        It is poor wording by the sales dood.

                        This from my Honda EU200i genset

                        " Limit operation requiring maximum power to 30 minutes. Maximum power is 2,000va"

                        " For continuous operation, do not exceed the rated power. Rated power is 1,600 va"
                        yea, the sales guy just used poor words and didn't know the reasons underlying what he was saying.....

                        Comment


                        • #13
                          Originally posted by Sandy View Post
                          Fill me in here tho. What you describe isn't so much of an 'ouput' issue as it is an 'engine life' issue. From what I'm getting here is that the engine isn't designed for extended full load duty, not that the genset will start putting out less, ie shortened life expectancy of the engine and not reduced output??

                          I visualize full load for whatever length of time I choose to demand it until 1) the engine pukes whether that's three hours or three years, 2) some thermal device on the engine shuts it down, 3) some thermal device on the generator/alternator shuts things down. What I can't visualize is reduced output after thirty minutes.

                          Sounds to me like either a misunderstanding on the salesmens part or, still, a marketing style play on words??
                          no, it is an output issue insofar as dutycycle is concerned - you are dealing with two mechanical devices here. engine makes rotation and horsepower/torque.... alternator on genset connected to engine converts the rotation and power to electrical power. look up specs on engine power curve, look up specs on alternator, overlay the two and look at the intersecting points for 1800 rpm (if 4 pole alternator) or 3600 rpm (if lower cost 2 pole version - less copper) and there is the point that will define the split between prime and standby power production capacity.

                          as for running it till it pukes.... the engine has a set speed. you wont overspeed it but you can burn up the alternator end of the genset if you try to constantly pull out more power than it can handle (it heats up too much and things like solder connecting parts melt)... or (normally worse) the things you have plugged into it....

                          IMHO, calculate up the load you think you will be pulling, add 50-100% to that and buy a unit that can do the in a continous use/prime power basis and you will be ok. you will likely use it well within the limits to make it last a long time.
                          Last edited by ChiliDog; 11-02-2008, 03:02 PM.

                          Comment


                          • #14
                            If it makes you feel any better, my LWS OSR had called the miller rep for our area on speaker for me and asked about generators and the miller rep said that (at least for my inverter unit) "all you need is a 6500 watt unit to be able to use the dx to it's full capacity" then stated the size of breakers i needed to run and when i looked at the machine (generator), it already had the needed sizes I was pleased to see that at least it was made to operate in the exact areas my welder is, although when one is maxed, so is the other..I'm not really bothered by that because i try not to run anything i own "tapped out" for any longer than absolutely needed just for thoughts of taking care of the machine and it's lifespan what ever it may be (except my motorcycle and 431 horse 4 banger turbo car..they get beat like they're stolen)

                            I didn't see what unit you're running but didn't go back to look either, I just think that one can not only "get away" with running a "common man's" style generator but that it can be done more successfully than most think... All i heard was "no way, not happening..bla bla bla" ...untill we got the miller rep on the phone.. When i went to get the genny ( it was barely used... and i mean really barely) the only thing i asked of the guy was to let me fire it up and run some beads at full capacity with my machine while having 2 other objects running off the 115 side (light and a 4.5" angle grinder) and it did it.

                            I made him an offer saying that i saw them near his price new (kinda) then he countered with showing me the receipt showing that he bought it when we got hit with our last big twister and lost power for a few days and everyone panicked because it hit a lot of local stores and such... He ran his house off of it for 2 days to keep his food from spoiling along with the meats in the deep freeze...... The oil in it was the factory stuff and still honey colored..sorry to ramble but i always get stoked thinking about the deal i got on such a good geny unit.

                            My best advice is, find a generator you want to buy/can afford and either find some one with one or tell the place you want to make sure it will do what you're buying it for. (pawn shops and sporting goods places will usually agree to these types of things...sams club, walmart ..not so much)

                            If you get it at wal-mart they have the 30 day no question policy.. if you aren't happy jst return it..... Or take a cover off, remove one wire and say it don't work, then ask for your money because "you've already bought another because you didn't have the time when you needed it to bring yours back"

                            Comment

                            Working...
                            X
                            Special Offers: See the latest Miller deals and promotions.