Constant Voltage Transformer Thingie

Discussion in 'Tech/Mech General' started by Ivys, Sep 26, 2011.

  1. Ivys

    Ivys Read Only Funster

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    Hi All

    I've noticed the voltage is low at my boiler. Planning to re-wire, and thought to use a constant voltage transformer. We've noticed some strange behavior when we run our genny etc. My thinking is that if I have a problem with boiler electrics it can't do any harm to use a constant voltage transformer.

    Does anyone know where I can get one from?
    I've googled for hours and all that seems to come up are LED transformers. For that matter, perhaps they would work?

    thanks
    Rog
     
  2. pappajohn

    pappajohn Funster Life Member

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    the vast majority of motorhome battery chargers are just that...a regulated power supply.

    if you have a switch to control the 'charger' (not the one on the charger) you can turn it off and still have 12v (nominal) to the hab area on Hookup.

    my kontiki had a three way switch to direct power where i wanted it....HAB battery/ENGINE battery/OFF.

    OFF gave 12v and around 15amps to the accessories without battery charging.

    sounds like you have a wiring fault to the boiler.....faulty switch or other high resistance.

    i found some on the RS website but a 50amp supply is around £450

    do a search for AC to DC POWER CONVERTER....not transformer.
     
  3. Ivys

    Ivys Read Only Funster

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    What I'm really after is a DC-DC 12v-12v constant voltage transformer. It would only need to be about 5 amps at the most.
     
  4. pappajohn

    pappajohn Funster Life Member

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    something like THIS

    10v to 28v input...stabilised 12v output and rated at 5.8amps.

    the fag lighter input plug and barrel type outlet plug could be removed and changed for any type you want.
     
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  5. Snowbird

    Snowbird Funster Life Member

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    I got 2 from Maplins, one for my TV and one for my Sat reciever, around the £20 mark each. 5 amps.
     
  6. Ivys

    Ivys Read Only Funster

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    Snowbird, do you have the product number?
    I might get one for my satellite kit.

    Rog
     
  7. Snowbird

    Snowbird Funster Life Member

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    Sorry I don't but they are about the size of a fag packet and come with all the different adapters.
    I got them because I have a large solar system and batteries are always showing above 12.8 volts and sometimes as high as 14 when boost charging.
    Have checked the output of the stabilized power supply and they are never above 12.1.
     
  8. Douglas

    Douglas Read Only Funster

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    John, it should be noted that the unit you point to is only 70 watt and is only sutable for no more that 6 amps consuption at one time.

    Doug...
     
  9. Ivys

    Ivys Read Only Funster

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    Doug, the Truma spec sheet says the C6002EH needs 5.6 amps, so 5.8 should do the trick (I hope).
    I'll test it and it it's not coping I'll use it on the satellite stuff.

    Rog
     
  10. scotjimland

    scotjimland Funster Life Member

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    Hi Rog

    Installing a 12/12 voltage stabilizer is a sticking plaster solution.

    You have given the solution in your first sentence... run heavier cable, I suggest 2.5mm

    Adding another component adds another potential point of failure ..
     
  11. Ivys

    Ivys Read Only Funster

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    I agree, but I'm wondering if the unit hasn't already been damaged. I noticed a few years ago that it would run the fans (but not actually heat) when I charged the batteries. On our recent trip the water seemed to get very hot, unless the voltage was "stable" at 12v. By hot I mean close to boiling.

    I know I have to change the cable anyway, and if the unit is damaged sticking plaster may be required. I'll wire it up so the cvt can be removed from the equation easily and quickly.
     
  12. scotjimland

    scotjimland Funster Life Member

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    Hi Rog

    What make is the boiler, have you checked what the voltage tolerance is ?

    From what you say it sounds like a fault with the boiler .. it should be voltage tolerant from about 10.6 to 13.4v or there about ...

    If the boiler board is damaged I would have it replaced, then after re wiring check that the supply voltage was within tolerance .. and if not, take steps to rectify..

    I still think fitting a 12/12 dc stabiliser is a last resort and won't solve the underlying problem of an unstable or out of tolerance voltage supply ... which may affect or damage other 12v kit ...
     
  13. Ivys

    Ivys Read Only Funster

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    The boiler is a C6002EH fitted by Truma UK a few years ago to replace my then leaking boiler. It's out of warranty now. :Sad: They (Truma UK) used the same incoming 12v supply as the old boiler. Whatever else I do I will replace the cables, coming straight off the batteries with an in-line fuse. That will mean I get at least 12v. We'll be using the van this weekend, so I'll get a chance to test the new cables.

    Once I have new wiring:
    How much would a new board cost?
    ..or, if it's the thermostat, how easy is it to get to?
     
  14. scotjimland

    scotjimland Funster Life Member

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    Sounds like a good plan.. and measure the voltage over a period, both on and off charge

    sorry, no idea how much a new board or stat costs for a Truma, or how easy to get at .. could try Olearys' Motorhomes for spares, they seem to stock just about everything
     
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