12 volt air conditioning

Discussion in 'American RV's' started by nahnotme, Jun 29, 2010.

  1. nahnotme

    nahnotme Read Only Funster

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    Im sat here in sweltering heat in spain with a fabulous air con unit but it will only work while on hook up, why dont they run on 12 volt ? can I power it from my battery bank through an inverter, what do others do, and dont say go on a campsite, down here they are few and far between, expensive, rarelly allow dogs and or big units.
     
  2. WillH

    WillH Funster

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    They don't make them because they wouldn't work. A 3Kw AC umit takes 12.5 A. Even a 200 AHr battery bank wouldn't last a day without charging. If you really need to fit one get a 5Kw portable genny.

    Rgds
    Bill
     
  3. scotjimland

    scotjimland Funster Life Member

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    yip.. they are power hungry beasts .. for each kilowatt it would be pulling 83 amps from the battery ... most units are around 1.5 kw

    However, there is one manufacturer who makes a 12v roof mounted unit for use on the move.. also requires an up rated alternator
     
  4. Dodgey

    Dodgey Funster

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    Assuming your in a RV and your not close to others, fire up the geni surely, or are you close to others, maybee answering my own question/answer......:Doh:
     
  5. vwalan

    vwalan Funster

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    there is a type of cooler based on the old evaporation easy cool system .it fits into truck roof hatches and you pump plain water up to it the sun evaporates the water a small fan blows air across the system into the cab or you pipe it where ever you want it. saw it at a truck show a few years ago seems its very common onthe continent .had a leaflet ,will try and find it . would work a treat in campers . strangely enough mine doesnt get too hot,i put the windows high and they act like a chimney andtake away the heat. even in the desert its cool in the back. done it by accident really but it works . dont even have a roof vent.
    cheers alan.
     
  6. GDH

    GDH Read Only Funster

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    I know that waeco do an air con unit for 24v that you can run overnight without the engine on, so it cannot use to much power. Not sure if they do a 12v version, might be worth a look though. Just go to waeco.com and have a nose. I also beleive that Road pro do a version, all be it at a cost.
     
  7. scotjimland

    scotjimland Funster Life Member

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    thanks, that's the make I was trying to remember..

    but even the smallest truck a/c unit is 800 watt .. pulling 33 amps at 24 volts.. double on 12 v
     
  8. JeanLuc

    JeanLuc Funster

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    DC Air-con units are available from Waeco / Dometic as mentioned, and from DC Airco (Roadpro sell these).

    The problem is the huge amount of current they have to draw from the limited potential of 12 volts. You need a monster bank of batteries to make it a workable proposition.

    The smaller of the two units in the link below draws 25 amps at full power and 12.5 amps on the lower power setting. So, if you have 200 Ah of battery capacity, or thereabouts, you could run the unit at half power for 12 hours and exhaust your batteries to 25% of their charge capacity (received wisdom says don't discharge a lead-acid battery below 50%, although Elecsol claim you can "deep discharge" without damage). That assumes you are not running any other 12V devices at the same time. If you need the full cooling effect of full power, the batteries would support a maximum of 6 hours.

    That leaves you with the problem of re-charging each day, so you would have to drive for quite some time or run a generator. If the latter is your preferred option, why not power your existing air-con unit with a decent generator - you might need something bigger than 2KVA to handle the start-up surge.

    Philip

    << Roadpro DC Airco >>
     
  9. vwalan

    vwalan Funster

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    tied to find the info i was on about but cant find it, it only uses a washer pump and a very small fan .its very economic on power thats their selling point. must have it somewhere . cheers alan.bet one of the other truckers know what i mean .
     
  10. JeanLuc

    JeanLuc Funster

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    Trav-L-Cool by any chance? They were fitted by Hymer at one time and are available from CAK Tanks in Kenilworth. See page 66 of their catalogue, which can be downloaded, or browsed on-line at:
    http://www.caktanks.co.uk/index.htm

    Philip
     
  11. scotjimland

    scotjimland Funster Life Member

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    I believe Hymer used to fit that type.. but as they depend on water evaporation they don't work well when it's high humidity ..
     
  12. vwalan

    vwalan Funster

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    12 volt coolers try googling bycool evaporative cab coolers . 12v or 24v that should do you.
    you could be both right i know that name. but these are used all over abroad on trucks.
     
  13. vwalan

    vwalan Funster

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    my cak cat is 2008 cant see it there but we got it in the end .could look on webb but not good i just found the other getting better.
    got it trav-l-cool page 64 in mine very similer.
     
  14. Elsbeth

    Elsbeth Read Only Funster

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    Air conditioning - with only a 1.5 amp draw

    This is a mains 220/240 unit but draws only 1.5 amps that means you could easily operate via an inverter of around 700w with capacity to spare (it's only using 300w when running flat out).

    Hook it on a window and chill out.

    and I guess if you're a wild camper it'll work quite nicely with a PV solar panel charging your battery for quite a few hours (if not all day).

    http://www.CoolMyCamper.com
     
  15. JJ

    JJ Funster

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    My 1987 Hymer 660S is fitted with a 12 volt Travel L Cool thingy. It blows air over water which is pumped up from its own (mini) tank. While it is not an "air conditioner" it is reasonably effective in lowering the overall temperature and is great if you set it to blow directly at you...

    ...uses a fair bit of electricity but you can't have something for nothing...

    JJ :Cool:
     
  16. JeanLuc

    JeanLuc Funster

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    Sorry to disappoint, but it doesn't work quite like that. The unit is quoted as consuming 350W when running on 230V. Divide 350 by 230 and you get 1.52 amps current drawn. However, if you plug it into an inverter, the 350 watts has to be provided by the 12 volts that feed the inverter. So the equation becomes 350 / 12 = 29 amps. Actually, you have to allow for the inverter's inefficiency too which will bring the current up to around 32 - 34 amps. The typical motorhome's battery bank will not last long with that rate of use.
     
  17. pappajohn

    pappajohn Funster Life Member

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    buy a fan and park under a tree. :thumb:
     
  18. JJ

    JJ Funster

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    But if you are under a tree (in the shade) how do you get electricity from the solar panels for your fan? :RollEyes: :RollEyes:

    JJ :Cool:
     
  19. Reallyretired

    Reallyretired Funster

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    According to the blurb 3.3A -5A which could be replaced by a reasonable solar panel (working on the basis that if you need to cool down the sun is probably shining). Also uses 0.5l -1l of water an hour

    I fancy getting one but can't see how they can justify charging nearly a grand for one. :Sad:
     

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