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Battery Drain Mercedes Hymer S500 Camper Van

Discussion in 'Electrics, Vacuum, Ignition and ECU' started by SL55 Mark, Jan 4, 2013.

  1. SL55 Mark

    SL55 Mark Senior Member

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    I'm struggling with a battery drain on our Mercedes Hymer camper van. We replaced the starter battery with a brand new one but still the drain continues. The habitation battery looks ancient, so I may have to replace that too.

    I'm about to hook up a trickle charger, which should give some idea of how much current we are losing.

    I've put a meter across all the fuses, and cannot find any drain. I'm wondering if it is the solar panels. Anyone else experienced a current drain from solar panels before ?
     
  2. television

    television Always remembered RIP

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    Only if the series diode is missing or short circuit in the solar panels
     
  3. wireman

    wireman Senior Member

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    I've put a meter across all the fuses, ??

    If you put a meter across a fuse very little voltage or current will be measured.
    You need to remove each fuse and test with an ammeter or milli-ammeter in series with not across the fuse. Take great care not to connect your ammeter across a 12v supply, this will destroy the meter.
     
  4. OP
    SL55 Mark

    SL55 Mark Senior Member

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    Thanks wireman, i have a multimeter set to measure milli amps do I need to touch the clips each side of the fuse cradle once I have removed each fuse ?

    With the fuses in I got a reading of 0.7 across the side light fuses once I switched the sidelights on, just as a test. All the other fuses were zero, apart from the instrument panel fuse, which read 0.5. Not sure what is going on really.
     
  5. cleverdicky

    cleverdicky Senior Member

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    Batteries can drain themselves if they have a duff cell or 2.
    Have you considered one of the solar cel trickle chargers?
    Usually cheap this time of year and they just keep the p.d. from falling to low.
     
  6. grober

    grober Senior Member

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    With everything switched off remove the battery earth strap and put the meter in current mode across that connection-- you should then be able to measure the current drain-- start on an amp range and move down to millamps You may have a faulty regulator pack on the alternator which is directly connected to the battery [ no fuses involved] If you have a current drain you could try disconnecting the alternator connector plug [ if it has one] to see if it stops? Caution remember that connector has a permanent live connection if the battery is connected!.
     
  7. OP
    SL55 Mark

    SL55 Mark Senior Member

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    I've got a mains trickle charger on it at the moment. The solar trickle charger idea sounds interesting, I thought that's what our solar panels were meant to be for, charging the batteries, not draining them :(

    There are two batteries, a habitation battery and a battery for starting, headlights etc. sound familiar to 230 owners ?

    The two batteries were connected in series, meaning a previous owner had bodged it to avoid having to buy a new habitation battery. :(
     
  8. pitch1

    pitch1 Senior Member

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    I have merc 210 and a Rapido Motorhome.

    Both vehicles drain battery when at rest and of course the motor home is at rest for considerable spells during the winter unless you use it a lot.

    I cured the Van by fitting a solar panel to the roof and now always have fully charged batteries however long he rest period.

    Only an observation of course,the eminent people who have replied already have made very worth while comments.

    Happy camping
     
  9. OP
    SL55 Mark

    SL55 Mark Senior Member

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    I think our solar panels are meant to keep the batteries charged, and that used to work in the summer. Fiona put a tarp over them a few weeks ago, après le deluge, to stop the roof leaking, which may have damaged them. Now we have a massive current drain. I would take it to a competent electrical engineer, but we can't even get it out the field its so wet, and I would like to resolve this myself if possible. Fiona is quite sad about it, as she loves her van.
     
  10. television

    television Always remembered RIP

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    You can get no sensible reading measuring across a fuse, the fuse must be removed to do a current drain check.

    The inline ammeter with a fuse plug that goes into the fuse holder are the best at only £6 to buy or you can buy a fuse adapter that uses you existing multimeter leads for £3
     

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