Fridge on hitch up

Catwoman66
Catwoman66 Forum Participant Posts: 4
edited July 2020 in Caravans #1

Our caravan fridge works fine on the electric hook up and on gas, however when we hitch it up to the tow car it does not work. We have had  both the car hitch and caravan hitch electrics checked professionally and they both seem to be working properly but the fridge still does not work when hitched up to the car. Any suggestions would be very welcome as we are now at a loss. 

Thanks Jacqui

Comments

  • EasyT
    EasyT Forum Participant Posts: 16,194
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    edited July 2020 #2

    DO you check the fridge is working with the car engine running above tickover speed? On tickover there is not usually enough current supplied by the cars alternator to power the fridge. 

  • SteveL
    SteveL Club Member Posts: 12,303 ✭✭✭
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    edited July 2020 #3

    Cars, more modern than ours, often have smart alternators that switch off when not needed. They don't know about the fridge. I believe I have read that putting headlights on can kid them into working continuously.

  • JVB66
    JVB66 Forum Participant Posts: 22,892
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    edited July 2020 #4

    The 12v on a fridge when you are hooked up shouldl only work with the car engine running,if it still does not work its possible that it is the cars "smart" alternator not recognising the need for power to the fridge, it is quite a common problem,your tow bar fitters should know about it and can fix it

    It is possible to when towing to drive on dipped headlights which will keep the alternator "working"

  • no one
    no one Forum Participant Posts: 216
    edited July 2020 #5

    Depending on the type of fridge ie compressor or absorption,The 12v supply from the cars alternator is only to keep the fridge cool, if starting from off it can take an hour of driving to chill it down to a normal fridge temp.

    it is recommended to cool the fridge on mains or gas first before driving off, then the 12v only needs to maintain the temperature already achieved.

     

     

  • KjellNN
    KjellNN Club Member Posts: 8,670 ✭✭✭
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    edited July 2020 #6

    Does the van battery get charged OK, or does the car have a smart alternator?  

    Is the fridge 12v element OK?

    Or does the light saying it is working just not  come on?

    A few more details would help with diagnosing the problem.

  • Catwoman66
    Catwoman66 Forum Participant Posts: 4
    edited July 2020 #7

    Thanks for all of the helpful replies. We have run the fridge when we have been driving and it still does not work. Within a couple of seconds of being connected and turned on the fridge  warning alarm goes off to say it's not working and this continues to go off through out the journey not just when the engine is ticking over. When it was serviced a couple of weeks ago they tested the fridge fully including on a hitch up and they said it is working. I don't know about the battery charging, we will have to check. The alternator was replaced a couple of years ago I don't know if that's why it's not working now.

     

     

  • JVB66
    JVB66 Forum Participant Posts: 22,892
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    edited July 2020 #8

    Before spending money ,next time out try the tip of having headlights on, if that works it will be the "Smart?"alternator 

  • EasyT
    EasyT Forum Participant Posts: 16,194
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    edited July 2020 #9

    I have never bothered to switch the fridge to battery. The fridge is run on EHU for a day before departure during which it is stocked. It makes a superb cool box and after several hours run goes on when we have set up. 

  • KjellNN
    KjellNN Club Member Posts: 8,670 ✭✭✭
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    edited July 2020 #10

     Make and model of fridge?

    Make and model of van?

    I am curious as to how you know it is not working when driving?

    There is a habitation relay in the van to cut off 12v while towing, other than to fridge and battery charging, could this be faulty, even though dealer says everything works.

    Did they test it on an actual car?  Did they test it on your car?

     

  • EmilysDad
    EmilysDad Forum Participant Posts: 8,973
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    edited July 2020 #11

    Because Catwoman says the fridge alarm goes off 😉

  • EasyT
    EasyT Forum Participant Posts: 16,194
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    edited July 2020 #12

    The only time my fridge alarm would go of is if it was switched to mains or gas with no power. Not on 12 volt

  • EmilysDad
    EmilysDad Forum Participant Posts: 8,973
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    edited July 2020 #13

    I wonder if the car's wiring for the fridge is man enough to cope with current draw .... 

    I've had similar with the tall fridge in my caravan but the other way round. My car will power the fridge but the box of electrickery that was used when being serviced said there was a fault .... presuming the fridge was trying to pull more amps than the test box could deliver. 

  • Catwoman66
    Catwoman66 Forum Participant Posts: 4
    edited July 2020 #14

    The caravan is an Elddis Avante 636 and I think the fridge freezer is a Dometic but would have to check. Nobody has actually tested it on the car despite us asking them to do this, they have always been tested independently of each other unfortunately. We will try with the headlights next time we go upto the storage site.

  • Pageantpete07
    Pageantpete07 Forum Participant Posts: 91
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    edited July 2020 #15

    We have to have the headlights on when towing for the fridge to work ,this was explained to me when i had my tow bar fitted. Next time you hitch up run your engine with the headlights switched on then check your fridge.

  • EmilysDad
    EmilysDad Forum Participant Posts: 8,973
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    edited July 2020 #16

    ,this was explained to me when i had my tow bar fitted

    Admittedly I've never been in this situation, but the advise from the tow bar fitter seems to me to be an admission that he/she didn't have a clue about modern cars' electrickery. I've no idea whether I have a 'smart' alternator on my 14 plate ML, but the factory tow bar electrics charges the battery & powers my fridge without the need to switch my lights on.

  • TonyBurton
    TonyBurton Forum Participant Posts: 269
    edited July 2020 #17

    I think you'll find this is a common problem with EU5 and EU6 engines. That's any diesel  built after about 2015. When the car battery is sufficiently charged the smart alternator saves energy by dropping the charge to both car and caravan.. The habitation relay in the caravan requires a slightly higher voltage to operate. I've given up on my Ford Kuga which has an after fit towbar.  I make sure the fridge is cold before I set off. I keep the door shut and rely on it remaining cool until I arrive on site. I believe you can fit a battery to battery unit that increases the voltage and charge to the caravan. 

  • KjellNN
    KjellNN Club Member Posts: 8,670 ✭✭✭
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    edited July 2020 #18

    Yes, I have fitted a battery to battery charger to make sure we have a cold fridge, and a fully  charged battery to operate the mover when we reach our destination.

    Easy to fit yourself if you can handle basic electrics.

    Everything now works as it did before we got this super smart Touareg!

    Something like this.......

    https://www.sp-shop.co.uk/Sterling-Power-Wildside-Caravan-Battery-to-Battery-Charger-PN-BBC1225.html

  • Catwoman66
    Catwoman66 Forum Participant Posts: 4
    edited July 2020 #19

    We tried the using it with the lights on but unfortunately that didn't help. The tow vehicle is a KIA Sedonna 2011 but the alternator was replaced a couple of years ago when it failed on a holiday in France. We have had the problem since then.

  • KjellNN
    KjellNN Club Member Posts: 8,670 ✭✭✭
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    edited July 2020 #20

    No, your  car would not have had one of these smart alternators originally, so you can rule that out, but possibly they have not connected everything back up correctly afterwards

    I would get that checked  out.

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