12v ac in my caravan

DevonDes
DevonDes Forum Participant Posts: 5
edited August 2020 in Caravans #1

 Hi,

I have just purchased a 1997 Burstner Scala and changed a couple of lights to LED lights, however the one in the bathroom keeps strobing and I have just investigated and found that the light in the bathroom is being supplied by 12v AC. Does anyone know why this might be?

Thanks,

Des

Comments

  • KjellNN
    KjellNN Club Member Posts: 8,670 ✭✭✭
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    edited August 2020 #2

    Most lights in caravans are 12V DC, so you can have lights even when not on EHU, then there are usually a couple of mains powered ones.

  • Whittakerr
    Whittakerr Club Member Posts: 3,472 ✭✭✭✭
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    edited August 2020 #3

    Are you certain its AC. How have you determined this?

  • SeasideBill
    SeasideBill Forum Participant Posts: 2,112
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    edited August 2020 #4

    I’m no expert but just a thought....

    Is the bathroom power source an inverter using a 12v transformer? Maybe supply intended for shaver point or similar? LED driver should fix the problem.

  • Whittakerr
    Whittakerr Club Member Posts: 3,472 ✭✭✭✭
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    edited August 2020 #5

    SB Shaver points are 240v going through a double wound isolating transformer

  • SeasideBill
    SeasideBill Forum Participant Posts: 2,112
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    edited August 2020 #6

    Yes, I know that.. was just wondering if that supply was from inverter but a lighting circuit had been taken off it stepped down to 12v? Can’t figure out how else it would be AC supply - that was the question posed. Some previous owners come up with very creative solutions to electricals!

    Probably well wide of the mark, but as I said I’m no expert.

  • hitchglitch
    hitchglitch Forum Participant Posts: 3,007
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    edited August 2020 #7

    What lights did you buy and are they on the mains or 12 volt (dc) system?

    LEDs take around 3 volts dc and are either connected in series with a resistor for a 12 volt dc supply or come with a driver (transformer rectifier) for a 230 volt mains supply.

  • DevonDes
    DevonDes Forum Participant Posts: 5
    edited August 2020 #8

    Hi, 

    I have just worked out how to add a photo! This is the front cover of the fuse panel/transformer box which says 12v AC. I also measured with a multimeter and got 0V DC and 13.1V AC.

    Not sure if being a German built caravan has anything to do with it- but I'm still a little confused as to why the test of the caravan is DC and the bathroom light is AC?

    Des

  • DevonDes
    DevonDes Forum Participant Posts: 5
    edited August 2020 #9

    Hi,

    Apparently, 12v to 80v DC! I don't have a battery in my caravan- I only get 12v through the fuse panel/ transformer when plugged into the mains.

    Des

  • Whittakerr
    Whittakerr Club Member Posts: 3,472 ✭✭✭✭
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    edited August 2020 #10

    I've not seen that set up before. The label shows two outputs from the secondary side of the transformer, fuse/control box 12v AC and 11v DC.

    You could get a rectifier for your bathroom light, but it will probably be cheaper and easier to keep the original fitting (presuming you still have it and it works).

    Alternately if you can trace the wiring you could switch it to the 11v DC output of the transformer.

  • SeasideBill
    SeasideBill Forum Participant Posts: 2,112
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    edited August 2020 #11

    Are you replacing a fluorescent tube? If so I think they usually run on AC hence the supply fitted to your bathroom.

  • DevonDes
    DevonDes Forum Participant Posts: 5
    edited August 2020 #12
  • SeasideBill
    SeasideBill Forum Participant Posts: 2,112
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    edited August 2020 #13

    Interesting, is there a medieval theme in you bathroom? wink

    What bulbs were fitted? 

    I think the solution to your problem is as previously suggested. Remove the transformer which presumably incorporates or feeds a fuse box to gain access to wiring feeds and swap the AC supply for the DC supply. Alternatively incorporate a LED driver in the existing power supply.

  • DevonDes
    DevonDes Forum Participant Posts: 5
    edited August 2020 #14

    All done. Traced the cabling back and connected to a spare DC connection. 

    The medieval theme has now gone!

    Des

  • SeasideBill
    SeasideBill Forum Participant Posts: 2,112
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    edited August 2020 #15

    Well done, I’ll bet you’ll miss those old light fittings! wink