I Need to Autostart a Generac 7.5kw Model 69981

BwBrownBwBrown Registered Users Posts: 2
My son has recently bought a remote homestead which has a modest but quite adequate solar and wind power system - there is no grid for miles. Water needs are powered by a brand new Generac 7.5kw Model 69981. It has the autostart panel wired in, but it must be manually started. It all works, but it is inconvenient. The Generac restores water pressure and provides some boost to the battery pack charge.
It occurs to me that the autostart function should be able to be initiated by the pressure switch when the water tank calls for water.
I read of 2 wire start conversions, but find little more than references - few details.
I look forward to learning about this, as I am not only assisting my son, but am pondering going off grid myself.

Just as an aside, while I like the Generac product, I am finding Generac customer support to be quite short on support.
I am not new to Standby generators, In my retirement I have a Cummins (LPGas)/Onan system on my remote farm-ette.

In short, the question at hand - How to add 2 wire autostart to a nearly brand new - less than a year old - Generac 7.5kw.


  • mike95490mike95490 Solar Expert Posts: 8,757 ✭✭✭✭✭
    Does the generac need a manual choke engagement when cold ? in 4 months from now, in the winter ?

    My first thought is to get a smaller water pump and a large enough inverter to run the pump.   Starting the generator 5x a day for 5 or 10 minutes to pump water, is going to wear it out quickly.  Pumping to a elevated tank, or to a ground based tank and then using a 12V RV water pump to maintain pressure might be another way to reduce generator time.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
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  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Or...pump once a day into a series of either holding or Pressure tanks so that you only have to start (and run) the genny once.  Plumbing multiple P tanks together is a a cinch.  How many gallons do you use a day.  Mike’s solution is also viable.  A large holding tank, feeding a supply to a small pressure pump into a pressure tank is also easy to do. Alternatively, depending on how deep the well, a submersible low voltage or slow line voltage pump with be a smaller draw, over a longer period but could run off the inverter (or battery voltage). We draw out of the lake into 60 PSI using a shurflo submersible that has been submerged for 11 years now and still seems to be fine.  

  • stillchillinstillchillin Registered Users Posts: 45 ✭✭✭
    I let my AGS start my generator by interrupting the commercial power input with a RIB relay, this just fakes the generator into thinking power has failed. Many ways to wire this in you just have to figure out when you want it to start
    18- 235 W Kyocera panel, 12- 4-KS-25PS Rolls 1350 Ah, Magnum MS4448PAE, ME RC50, ME AGS, Outback FM 80, Generac 8KW LP generator, 6.5 Honda Portable generator
  • BwBrownBwBrown Registered Users Posts: 2
    I agree with all the above observations. We have two water pressure tanks, 120 gallons each, with a 20-60 pound switch they have an effective draw down of nearly 90 gallons between cycles. This would require running the generac once a day at the most.
    There is no utility power, no commercial mains, the nearest electric service is more than two miles away. This is a totally off grid installation. The once or so daily run of the generator brings water into the system and provides a little supplemental charge to the batteries. Most days the PV panels and wind generator keep them adequately charged.
    We can go out to the Generac, push the button and everything works as it should - very cool!

    But we want to automate it - to eliminate the necessity of my daughter-in-law trekking out into the snow to push the button - to use the pressure tank switch to activate the generac start sequence. I can find no schematic which indicates which wires do what. It really should not be a mystery as to how to include a relay or three, a couple simple timers, to sequence things.

    A simple schematic of the Auto Transfer Box and the Generac should indicate which connections could make this happen. I am not a stranger to electronics, spent several years in commercial broadcasting, am an amateur (HAM) radio operator. I can build and maintain 1.5kw RF amplifiers, which often run more than 4,000 volts!

    What continues to elude me is which wires will effect this remote start. I respectfully ask some kind soul to teach me how to wire up the remote start of the Generac. I see reference to the "Generac 7109 Two Wire Start Kit." 

  • EstragonEstragon Registered Users Posts: 4,478 ✭✭✭✭✭
    Prefacing remark; I don't know much detail about Generac generators.

    I assume the "autostart panel" is an automatic transfer switch (ATS) which includes breakers (or spaces) for critical load circuits.  In a standby power application, the critical circuit(s) would be wired to the ATS.  The ATS would normally be powered by grid power.  In the event of a grid power failure, the ATS starts the generator to power critical loads only.  Presumably (hopefully) there's logic somewhere to allow warm-up time, check oil pressure, etc before powering the critical loads.

    Being off-grid, the wiring may be different though.  Is the pump connected to the ATS breaker, a main panel breaker, or directly to a generator breaker?  I'm guessing the latter (so pump can only run if the genny is running)?

    If my (too many) assumptions are right, @stillchillin idea may be on the right track.  The pump circuit could be moved to the ATS.  The "grid" input to the ATS would be powered via a normally closed relay from the inverter.  The pump switch would trigger the relay open, appearing to the ATS as a grid failure, and making it start and power the pump.

    (At least) a couple of potential issues with this:
    1.  This relies on there being logic for warm-up and stability checks in the ATS and/or genny control.  I'd guess there are, but if not, the relay trigger would need to include same.
    2.  If the inverter power is lost or turned off, this triggers to relay and starts the genny.  Is there a key that needs to be switched on that could be turned off to disable this?

    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • shawnj72shawnj72 Registered Users Posts: 52 ✭✭
    Hello, Fellow Ham Myself Electrical engineer But fairly new to the solar myself. But with that said. It should be Fairly Straight forward Terminal 23  Terminal 194 are the auto Start. you could plumb in a secondary Pressure Switch and run the Terminals to the second set of contacts.. when the pressure falls below set point it will close the contacts and Presumably if all conditions are met start the auto sequence of the Generator as if it was hooked to a transfer switch.. but unknown how often this would occur you may look at ways to keep this from happening frequently.. AKA cheep Controller of some sort.. Pi or PLC or even timer circuit. Hope this helps and gets you in the right direction.. Regards Shawn KU0D 
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,181 ✭✭✭✭✭
    Schneider and Outback (others may also) both have AGS electronics that have give you many options to start a genset! Any chance you have one of these inverters. Why reinvent the wheel?

    This can be done remotely on the web also with Insight2  and Optics from Schneider and Outback.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
    E-mail [email protected]

  • xolarxolar Solar Expert Posts: 27 ✭✭
    My experience has been that the Generac generator starts on the loss of 240 vac and in the past I have just fed a 240vac circuit to the unit that I interrupted with a relay, this particular relay was a 12 volt coil that was controlled by the inverter.  Initiating the generator to run on low pressure would be simple using a second pressure switch, a couple of inline timers to allow for a warm up before connection and to allow a short cool down cycle. 

    Does your inverter produce 240 volts?
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