Dometic Fridge not working on 12v?

Discussion in 'Tech/Mech General' started by tonywolst, Sep 4, 2011.

  1. tonywolst

    tonywolst Read Only Funster

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    I say not working, it only works when I'm driving, I just assumed it wasn't working as when I turned it to 12v no light came on, However today the misses noticed the light was on when the engine was running, Has it been wired up wrong, ie to the engine 12v circuit and not the leisure circuit, or is this how they work, so 12v only whilst driving, then onto gas or ehu?
     
  2. sillybug

    sillybug Funster

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    think thats how they work well i always assumed that 12v worked while we were driving then when we stopped either plugged in electric or put on gas maybe somebody will correct me if im wrong but thats how mine works hope this helps:thumb:
     
  3. Simba

    Simba Read Only Funster

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    On my MH 12v only works when engine running when on site use gas or EHU. Thats the way it is set up.
    Bill
     
  4. welshbois

    welshbois Read Only Funster

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    That is what It seems. Works on battery while driving and acts as a chiller. When parked up go on gas or EHU.
     
  5. tonywolst

    tonywolst Read Only Funster

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    Thanks All.
     
  6. activecampers

    activecampers Read Only Funster

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    By design.

    3 way fridges can work on 12v but only to "maintain" temp, not cool (so the theory goes, but ours cools). The power draw is quite large (10A? Ours is fused at 15A), so that will flatten an 80AH battery in 8 hours!!!!

    So there SHOULD be a split charge relay (or voltage sensitive switch) that when the engine is running and hte alternator is making the vehicle voltage above 13.6v it connects the vehicle 12v to both the fridge 12v to run the fridge, and to the leisure batteries to charge them.

    Without this switch in place you would flatten your vehicle battery :(

    You CAN get 12v fridges but these are "compressor" fridges, typically a bit smaller, and typically the vans have extra batteries to cope.

    A 3-way fridge should not run off the leisure batteries (though some may be connected to the AUX on the leisure side to run the fridge electronics/gas ignitor only etc)
     
  7. wizzer59

    wizzer59 Funster

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    Correct:thumb:
     
  8. tonka

    tonka Funster Life Member

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    Slightly off the original point of the topic but may be of use to someone..

    We had a trip once back up from Spain and put the fridge on 12v to keep to cool while traveling, however the trip was in rubbish weather and a bit cool. So we had headlights on, wipers goin, radio on, heater blowing.. You get the picture..
    Outcome was of course the alternator struggled to keep up with it all and put very little charge in the leisure battery.. That night we got by but leisure battery was very low..
    Later discovered just how thirsty the fridge is on 12v (10 amps)...
    So just be careful if you rely on having your leisure battery charged while driving..
     
  9. callumwa

    callumwa Read Only Funster

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    Our old van had the Dometic fridge with manual control.

    ie switch to 12 v for when the engine is running, and gas or 240v when stopped.
    But you had to switch it so it works.:cry:

    Our current van has auto system which switches to 12v when engine running, 240v when on EHU, and gas at all other times. :thumb:

    Much easier as I always forgot to change the manual control on the old van so got fed up with warm beer nd wine.........:Doh:
     
  10. peaps

    peaps Funster

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    Hi
    our van has the same as your old van just as many before and as tuggers many years ago the 12v and 240v get left on permanently and I just light the gas when required, never had any problems in 30 plus years HTH.

    Pete:thumb:
     
  11. Taran_Las

    Taran_Las Funster

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    One recommendation given to me was to run the fridge on EHU for a couple of days (before your journey) to chill off. The 12v will keep the contents chilled. If you don't do this running on 12v will keep the contents nice and warm!:Laughing:
     
  12. Reaynger

    Reaynger Read Only Funster

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    Wouldn't a solar panel kit keep the fridge running so we can be independent from EHU and gas? Seems it is a bit daft that you can't run a fridge on a really sunny day whilst selected to battery. :cry: Or does that change when you get the solar?
     
  13. activecampers

    activecampers Read Only Funster

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    If you get a big enough solar panel it can - but 5-10A constant for a 3-way fridge. and then what about overnight?

    A smaller compressor fridge that only runs on 12v is a bit cleverer, and at 5A draw at, say, 1/3 of the time, needs 40AH per day. So as long as your 80W (5A) solar panel has full sun for 8+ hours...... (or 160W for 5-6 normal hours...)

    So doable but just do the math
     
  14. Rayb182

    Rayb182 Funster Life Member

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    On our Kontiki I just put it on auto and it will either run on battery when driving, solar if theres sun, or it will change by its self to gas when theres no sun.
     
  15. pappajohn

    pappajohn Funster Life Member

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    Close, but no coconut :Wink::Laughing:

    you should never discharge a battery to below 50% of its fully charged state, so an 80ah battery will last 4hrs at 10amp drain.

    go below 50% and you run the risk of damaging the battery permenantly. :Sad:
     
  16. aba

    aba

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    so i guess that my battery took a bashing when it got down to 10.2volts then:Doh::Doh:
     
  17. pappajohn

    pappajohn Funster Life Member

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    yep!!! 10.2v is considered a dead battery....not just flat, but dead.

    you may get away with it once or twice but certainly not every time.

    i believe it depends, to some extent, on how long it was at 10v before recharging.
     
  18. aba

    aba

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    not long as i started the engine and let it run for 20 / 30 minutes it seems to have recovered as it sits quite happily at 12.8 volts
     
  19. activecampers

    activecampers Read Only Funster

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    It was only for illustrative purposes, and you are close but no bananas, see http://www.elecsolbatteries.com/faqs/#07 - some batteries are fine with deep discharge :p So if you have the elecsol batteries, you could drop more...

    No - voltage may recover but that doesn't indicate it is full. Even if needle/meter in green. No simple/cheap way to see state of battery charge from a meter. 30 mins at, say, 20A charge only adds 10AH to your batteries - so misleadng I am afraid :( Only way I know is to have a clever unit measing current in/out and then calculating capacity.
     
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