Running rooftop ac with reefer

Discussion in 'Ask An Owner Operator' started by bulldog36, Aug 19, 2014.

  1. bulldog36

    bulldog36 Bobtail Member

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    Have been looking at a rooftop ac/heater and was wondering if anyone hAs tried this approach using 2 to 4 dedicated batteries and Using the reefer for power/ charging?
     
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  3. dieselfuelonly

    dieselfuelonly Road Train Member

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    You would need a monster alternator to keep up with a RV-style rooftop HVAC unit. I've looked at doing something similar instead of using an APU on my next truck but plan to use a small Yamaha generator instead to power it.

    Anyway, I'm not at all familiar with reefer units but I am gonna guess they probably use an alternator similar to what you would find in a TriPac unit which I think by default are 60 amps or you can upgrade to a 120 amp version.

    I've looked at the Dometic DuoTherm units which have electric heat as well as providing 13.5k BTU AC. If I remember correctly they draw the most when running the heat which was around 13 amps at 120v AC.

    13 amps @ 120v AC = 1560 watts

    Now we take 1560 watts and divide by 12.5 volts and that comes to around 125 amps DC.

    Of course its not going to be a 100% efficient conversion through the inverter so lets play it safe and say the loss is 20% and that now comes to around 150 amps.

    Remember too that you would need a SERIOUS inverter to be able to handle the starting load of the compressor.

    If someone made a 200+ amp alternator for the reefer unit I could see it being possible. Use a high quality sine wave inverter and you should be able to power it if you could find an alternator that could keep up.
     
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  4. Passin Thru

    Passin Thru Road Train Member

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    Too much weight added and would be problematic beside. Easier to install AP
    U and RV Air.
     
  5. KenworthGuyNH

    KenworthGuyNH Road Train Member

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    Much simpler approach is the small Honda generator (nicely installed) with a Dometic rooftop and a good charger/inverter. Look at Leftlanetruckin's setup. Rontonio and others have similar.
     
  6. Passin Thru

    Passin Thru Road Train Member

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    Can be Coleman, Duotherm, Dometic or Carrrier. We ahve a Coleman and love it, powered by a Onan, 7.5 diesel Generator and it's 110 V. You can plug in the trucks heat, put aceramic heater in the cab and it adds 475 lb to the truck.
     
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  7. notsonewb

    notsonewb Light Load Member

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    Rather than roof top I would prefer a split unit where the pump is out side and the cool/heat unit is inside ,less chance of a roof leak and less ugly tall thing ect , could put the pump out on the back porch , but like was said the power to run it is the thing , I have a similar set up on my motor coach , w/ 2 8D batteries w/ the dedicated 150 ish amp alt when engine running is ok, but will only run a couple hours without a charging source, running a 2000 watt generac will run it but the fuel it takes well its just not really efficient, I will also be adding 400 watts solar panels to the system but it will still require additional power ,
     
    Last edited: Aug 20, 2014
  8. dieselfuelonly

    dieselfuelonly Road Train Member

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    Got any reccomendations for the split system that can run off a 2400w gen?
     
  9. slavcha

    slavcha Light Load Member

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    You can get Chinese 2500 watt generator separate motor and put AC clutch on generator part to have a switch on and off when not needed, add pulley and belt to your reefer unit and you have all the power you need to run AC.
     
  10. Joetro

    Joetro Road Train Member

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    A friend of mine installed a Coleman on his ProStar and runs it with a gas generator. He swears by it.
     
  11. Johny41

    Johny41 Road Train Member

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