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philo111's avatar
philo111
Explorer
Nov 06, 2016

Portable A/C unit

have a Camper Box Truck with a 14' box. I also have a 10,000 BTU portable A/C that uses 1200 watts / 10.8 amps).
I would like to run the A/C for several hours without a Honda type gas generator.

I was thinking:
I could upgrade the Truck Alternator to one that produces
100 amps at idle.

Get a good quality Deep Cell Battery that holds 200 amps.

Get a 3000 watt inverter.

Plug in the Portable A/C.

Start the Truck and just let it idle for hours when the A/C is
on (the engine does not over-heat).

Would this work?

Thank you for your thoughts!
Seeking Advice

19 Replies

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  • philo111's avatar
    philo111
    Explorer
    Nov 06, 2016
    donn0128 wrote:
    1, truck motor at idle will burn lots of fuel and lots of polution
    2, 100 A alternator is rated amps at XXX RPM, not at idle
    3, a single battery can only supply about 50% of its rate before it is considered dead.
    4, 10.8A at 120VAC means the inverter will draw approx 110Amps at 12VDC to run the load.
    Any more questions?


    Thanks for the reply.

    The alternator is rated at 100 amps at idle and 200 amps at 1200 RPM.
    The truck idles at .2 gal. per hr.
    The emissions are non issue.

    Still not positive why this won't work?
  • theoldwizard1's avatar
    theoldwizard1
    Explorer II
    Nov 06, 2016
    Hmm ... I wonder why those guys were so quick with one word answers !

    I will say "Maybe !"

    2 problems against you.

    1. Truck charging system. If you really want to try this, you really need to bypass the trucks battery and hook up the alternator directly to your deep cycle battery. That, and you will likely have to come up with a way to run the engine at "high idle".
    2. A/C starting surge current is a big problem. Newer portable A/Cs draw less.


    If you are going to try this, make sure you have a GOOD pure sine wave inverter and you are going to need something like a Trojan J185H-AC battery ($300) or LARGER !

    Also, when you are done running the A/C, you need a good 3 stage battery charger. Hook the track battery back up, hook the inverter to it and then re-charge your other battery. This might take a couple of hours !
  • spoon059's avatar
    spoon059
    Explorer II
    Nov 06, 2016
    Carbon monoxide poisoning sounds like one major reason why its a bad idea.

    It sounds like the ideal solution is a smaller inverter style generator, which you have already ruled out. To me, the better question is "why" or "how come" you won't use a proven tool to do the job you want done?
  • donn0128's avatar
    donn0128
    Explorer II
    Nov 06, 2016
    1, truck motor at idle will burn lots of fuel and lots of polution
    2, 100 A alternator is rated amps at XXX RPM, not at idle
    3, a single battery can only supply about 50% of its rate before it is considered dead.
    4, 10.8A at 120VAC means the inverter will draw approx 110Amps at 12VDC to run the load.
    Any more questions?

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