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PTO driven Generators...

Post in 'DIY and General non-hearth advice' started by Redbarn, Jul 13, 2013.

  1. Redbarn

    Redbarn Burning Hunk

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    Well Folks, Hurricane season is not too far away now...

    I have used 2 Gas powered Gennys in the past to power our home and this setup works well.
    However, this requires holding a good (40 gall) supply of gasoline around the place.
    We can hold out for 12 days with this fuel before falling victim to a gas shortage.
    Syphoning fuel from our vehicles would extend this but at the risk of reducing our ability to drive to sources of fuel.

    I have diesel tanks around the house and outbuildings that hold a combined 750 galls of diesel.
    We also have 2 tractors with Class 1 PTO takeoffs.
    I estimate that using a PTO driven diesel Genny, we could last for 3 months easily.

    I'm looking at a PTO driven Genny to run the Well pump and other stuff that doesn't need clean power.
    I would still use the small Gas Genny to run computers, TVs and other stuff needing clean power.

    Has anybody any experience with PTO driven Gennys like the link below that they'd share ?

    http://www.northerntool.com/shop/tools/product_200308467_200308467

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  2. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

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  3. Redbarn

    Redbarn Burning Hunk

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    Our small tractor has a 10HP PTO. This should produce circa 5000 watts of power, using circa 4 galls of fuel/12 hr day.
    The Northern Tools PTO Genny is rated at 7200 watts but provided our small tractor can reach the required rpm, should produce 5000 watts peak load ok.

    A bigger Genny is tempting but would require using our larger tractor.

    At the moment, we use a 5000 watt Gas Genny for 1 hour a day for showers etc.
    Using the PTO Genny would extend this range to 8 hours/day.
    We'd still use the Gas Yamaha sine wave genny in the evenings to watch TV, do email etc. etc..
  4. jeff_t

    jeff_t Minister of Fire

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    I have friends that ran a generator on the 1000 rpm shaft of a 956, for days at a time. Their load wasn't huge in the summer, and running the 540 rpm generator on the 1000 rpm shaft allowed them to run it at half throttle for reduced fuel consumption.

    The 956 is long gone, and the generator is now a propane fueled standby unit hooked to 4000 gallons of LP.
  5. Joful

    Joful Minister of Fire

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    Likely the only way one could justify putting hours on their tractor, when generators are so cheap. Do you really want to be running your tractor at PTO rpm to power a generator for hours on end?
  6. jeff_t

    jeff_t Minister of Fire

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    Depends on the situation. If you have big power requirements, and a big tractor to spin a big generator, then the hours make more sense than having another engine to maintain.
  7. jebatty

    jebatty Minister of Fire

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    I have a 10,000 watt pto genny which I picked up used at a very low price; runs off the 540 rpm pto. I just run it from time to time to make sure it works and that the mice haven't eaten up the insides. I also have no need for a genny this big. The 5000 watt gas genny with transfer circuits on the main panel in a real emergency is needed only to run the well pump, and we could get water from the lake and boil it over a wood fire if we had to. Transfer circuits also power the refrig and freezer, as well as general lighting (CFL) circuits, the microwave, and a couple of outlet circuits. I think the 2000 watt inverter genny with extension cords should power the refrig and freezer in an emergency, at least enough not to spoil the food, and that uses very little gas. I do pretty good in keeping 15-30 gallons of gas + 6-12 gallons of diesel on hand all the time.

    We are planning a solar electric install this summer, micro-inverters. That should have a disconnect/transfer switch so we could run 100% solar when the sun is shining in an emergency. I would not want a large battery bank, but a couple of 100 ah deep cycle batteries fully charged would do a lot to run the circulator for the shop heating system.

    If they could make it to our home, our children and families all live about 175 miles away, and their plan in an emergency is to get to our house. That's might be better than staying in the city, but that choice would have to be made at the time depending on the nature of the disruption. Our home can be kept warm and have water and sewer. And then it will be time to eat the cottontails and squirrels.
  8. Joful

    Joful Minister of Fire

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    I am not an expert on this, but the PTO generators I've checked out are never cheaper than a gas powered one of equivalent capacity, by enough $ to make it worth putting hours on the tractor engine. Besides, if you need big power with reliability, just install a nat gas or propane powered stationary plant.
  9. Redbarn

    Redbarn Burning Hunk

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    Concerns about putting hours on a tractor diesel should be discounted. Those motors are very rugged, low tech and built to run for ever. It is Retail gas powered motors that are likely to fail.
    My key concern is fuel avaliablility. We use Pellets and wood now for heating but still have circa 750 galls of heating oil on hand in various tanks.
    This would be an almost inexaustable supply for a diesel powered PTO Genny.

    For sure the PTO Gennys are not cheap. A stationary nat gas or propane unit also cost big $$ and still require maintenance.
    Our use pattern has been 2 x 7 day outages per year. I see this getting worse not better.
    So the PTO Genny route plus our existing Yamaha inverter genny would work fine.
    Besides, my wife can start the tractors easily but has trouble getting our current gas powered genny going.
  10. jeff_t

    jeff_t Minister of Fire

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    I'm talking about cows that need to be milked whether there is power or not. And that milk needs to be cooled. If you ever watched a 150 hp tractor jump and belch black smoke when the milkers are turned on, you would know what I'm saying.

    I agree, for residential use, it might not make sense.
    Dairyman and Joful like this.
  11. MasterMech

    MasterMech Guest

    If you have the tractor, and the fuel consumption numbers play out, PTO may be a good way to go. Just because of the reliability. It's likely the tractor gets regular exercise and is kept in working order for other tasks other than generating electricity. The downside is that it ties up a tractor.

    The idea to run the genny off the 1000 rpm PTO at half-speed is a good one for larger tractor owners that have that option. Deere has a "E-PTO" option that accomplishes the same thing. Available on 4x20 series tractors and bigger I believe. Saves fuel and wear and tear on the engine as well, no need to have a 60+ HP engine screaming at 2400+ RPM (to make 540 rpm on the PTO) when you only need 30HP to make the power you need.

    Putting hours on an engine isn't a bad thing either. PTO genny is pretty easy time for most tractors. ;)

    We have a 60Kw Nat. Gas powered backup generator at work (doesn't power the plant, just a few essentials and emergency lighting) that's running a 6.8L Ford V-10. Hollers pretty good when the 60HP cooling water pump spins up. ;lol
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  12. Highbeam

    Highbeam Minister of Fire

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    So my tractor is 30HP diesel and has a PTO speed selector lever, 540 rpm is forward, middle is neutral, and back is 1000 rpm at 2500 rpm engine speed. I mowed for 10 hours straight this last Saturday at 2500 rpm using the 540 of course and used 10 gallons of fuel. Seems that whenever the engine is at full rpm that fuel consumption is one gallon per hour whether mowing light dry grass or thick wet grass. A diesel running at 2500 rpm is loud, I wear ear protection all day. Not good for a genny but with the 1000 pto option you can lope along at a low 1250 rpm which is just above idle. Now here's the trouble, our tractor engines are designed to make power and keep cool at 2500 rpm so at 1250 there won't be much of either. You won't have the output to do anything and worse yet, you will quickly lose rpm which means hertz and possibly voltage would drop. You don't want to do this to your devices.

    If you need big power and have a big tractor, a pto genny is a very cheap way to get it. I do not believe that they are a wise option for residential loads. You won't save much fuel, you'll spend more money on the pto genny than you would on a standalone that makes the same quality of power, and you have to listen to that thing scream. My wife does not hookup PTO equipment, there are lots of nasty ways to die while hooking up tractor implements.

    Buy a bigger fuel tank. Heck, a 55 gallon barrel of gasoline can be filled and a 15$ HF crank pump used to pump gasoline to your jerry cans.
    Joful likes this.
  13. MasterMech

    MasterMech Guest

    IIRC the E-PTO option found on the Deeres runs the engine at about 1700RPM and is available only on machines that put out significantly more than 30 HP. ;)

    The idea is to generate much less noise and cut fuel consumption by using less power from machines that have plenty to spare. The OP of course, with his 10HP tractor, would be running flat-out.

    No need to go through the whole routine. Two ways to make that easy:

    1.) Quick hitches - which I admit are imperfect and don't work for every implement
    2.) Permanently mount the generator in a building or a "dog house" and simply back the tractor up close and somewhat straight. Connect 1 shaft and you're done.
    Dairyman likes this.
  14. ironpony

    ironpony Minister of Fire

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    I personally can not see running a 10,000 dollar tractor to power a residence. I would much rather run a 600 dollar stand alone, unattended, alot less to recoup if something goes amiss. with that being said I do have a 20k diesel stand alone unit that I will let run as long as neccesary unattended but it is built for that, a tractor is not.
  15. MasterMech

    MasterMech Guest

    Why is everyone afraid to run their tractors? :p
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  16. Highbeam

    Highbeam Minister of Fire

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    Why not? I spent 10 hours on Satuday mowing a pasture with the tractor. What's more important? Low grass or utility power to the home?

    Tractor engines are made to be run, if you don't run them then they just sit.
  17. Joful

    Joful Minister of Fire

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    Where are you buying utility tractors for only $10k?!?



    See above.

    Not afriad to run, mind you. I just don't see any valid reason to put hours on a $20k+ machine when you can buy a good stand-alone generator of equal capacity for $1k. Again, the OP inquired about residential use, not agricultural use.
  18. Jags

    Jags Moderate Moderator Staff Member

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    Running a 7200 watt genny underpowered can cause problems. Assuming that your governor will maintain proper voltage/cycles to about 5000 watts (as you stated). You go to 5050 watts and you will start pulling down the motor and the governor will not be able to adjust for the load (out of HP). This will cause a drop in volts/cycles. That is bad mojo for motors of all kinds. And it will be something goofy that causes it, like the defrost cycle on your fridge or something else unexpected.
  19. Redbarn

    Redbarn Burning Hunk

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  20. Redbarn

    Redbarn Burning Hunk

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    Reference the discussions.
    I figure that the math like this:

    Annual Genny use is 14 days x 8 hours/day = 112 hours

    if a PTO genny costs, say $800
    Cost for using diesel tractor (no counting fuel cost)...zilch.
    Most tractors will run for 4000 hours without issue.

    Big Box store $800 gennys are reputed to last 600 hours.
    So after 5 years or so, you need a new genny but the PTO genny will still be running fine.
    To get a 7Kw gas Genny that will last, you need to get a big Honda but these cost $4000 plus.

    Interestingly, all the electric engineers that I have discussed this with have recommended getting slightly more Genny than input power. The thinking is that the fossil fuel motor then cannot overpower and fry the Genny. If the electrical load jumps, the Genny may stall the input motor so load matching is key to a successful setup.
  21. Joful

    Joful Minister of Fire

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    Your neglecting depreciation on a potentially expensive tractor, and assuming that PTO driven generator has infinite life. Your post indicates you expect to run 600 hours over the course of 5 years. Many (most) compact utility tractors log more than an hour per running hour at PTO rpm, so you'll be putting more than 600 hours on the hour meter every 5 years. Just food for thought...
  22. Redbarn

    Redbarn Burning Hunk

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    True.
    However, I already own a 5 year old Big Box store Genny but have a neighbor who is interested in buying it, as it as already been used at his house in a storm. So that reduces the capital outlay for a new Genny.
    I already have the tractors and consider them as capital expenses. I tend to buy new and keep stuff for at least 10 years, so the hours on the motor do not greatly affect its trade-in value at that stage.
    The key question is whether the PTO Genny will run 600 hours every 5 years easily without issue.
    That steers me away from Chinese sourced Gennys.
    Still researching...
    Joful likes this.
  23. maple1

    maple1 Minister of Fire

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    Anybody who owns a real tractor, and is considering a PTO generator, should not rule it out just for the reason of being afraid to put hours on their tractor. Tractors are made for running hours at a time - we're talking two weeks of use per year in this thread, that is nothing.

    If you've got a tractor that will run PTO speed at a reduced engine speed, double bonus. That thing will purr along quietly with low fuel consumption and keep the lights on. I'm going to be running a tractor here next month, for three weeks straight, 12 hour days, at 1500 rpm, with a lot more load on it than sitting still running a house-sized generator. It won't feel a thing.
    MasterMech likes this.
  24. Highbeam

    Highbeam Minister of Fire

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    This goes back to the flawed "problem" and loss of value by running the tractor engine. It is supposed to be run. I have 1200 hours on my current tractor that I put on over the last 6 or so years. It's just getting broken in. The age and condition of the tractor is what causes depreciation. The hours, unless extreme, have little bearing.

    About this PTO hour vs. operating hours thing. In my experience, the hour meter accrues true hours at PTO speed and at lower engine speeds accrues less than true hours. The engines are designed to run at PTO speed so that is where they measure true time. Has anybody ever actually seen an hour meter run more than 100% of actual time?

    Those PTO gennys are like most things. There is the cheapy crap version and then there is a heavy lifetime version. Power quality and lifecycle are related to price. If you just want a PTO generator then get one but I don't think you can justify it for residential loads. More of a fun factor.

    And you do NOT need to buy a Honda 4000$ genset to get a 7000watt portable generator that will "last". Hondas are nice but at that power level they are not inverter sets so the Honda advantages are minor.
  25. Jags

    Jags Moderate Moderator Staff Member

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    I have never seen an hour meter do that. All that I have seen are electric versions that run off of the ignition. On/off with ignition. Dunno, maybe with the 'tronics on this new stuff they are based off of rpm. Kinda cool but I have never seen one.

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