Battery dead?

Discussion in 'Tech/Mech General' started by johnp10, Oct 19, 2010.

  1. johnp10

    johnp10 Funster

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    The liesure battery on my MHhas been holding a reasonable (ish) charge for about 10 days or so, after which time I have been plugging in EHU.
    It was ok for the weekend at Newark fair.
    I have just taken the MH for a run.
    At the start of the run the battery indicator was showing 3 from 5 lights, being 1 red, 2 yellow.
    At the half way point (30 miles or so) it was reading the same.
    On return it's reading 1 red, and hab lights are so dim I cant see the point of measuring the voltage.
    I will check readings tomorrow before and after EHU.
    All 12v switches are off at the control panel.

    a) Battery knackered?
    b) Can the vehicle drain the hab battery? (veh battery reading 12.9).
    c) Can the split charging relay have thrown some kind of wobbler and
    discharged the battery?

    Suggestions welcome.
     
  2. Snowbird

    Snowbird Funster Life Member

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    Everything points to a split charge problem.Pot a volt meter on the leasure battery with the engine running to confirm if its charging from the engine.
     
  3. pappajohn

    pappajohn Funster Life Member

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    more than likely the relay has failed.
     
  4. johnp10

    johnp10 Funster

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    Cheers Folks.
    I'll try that tomorrow.
    If the split relay has wobbled, will that discharge the hab battery?
    I've never got as far as all 5 indicator lights on, (red, 3 yellow only, no green) even after EHU for a weekend, except when actually hooked up.
    If the relay is ok, could be a good time to uprate the battery and fit a second one.
    Should I also suspect the battery?
     
  5. pappajohn

    pappajohn Funster Life Member

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    a battery can fail at any time without warning John...

    internal open circuit is a favourite.


    if the relay is stuck 'closed' without the engine running it will draw power from the hab battery AND the eng battery at the same time.

    do as Dave said and put a volt/multi meter across the hab battery then start the engine and check volts.

    if it shows 13.6v upwards then its charging ok so suspect the battery.
     
  6. pappajohn

    pappajohn Funster Life Member

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    it happened to us heading for spain.....but the other way round.

    we had a 12v cool box between the front seats for 'on the road' drinks etc running off the hab battery and the relay failed subsequently the cool box killed the battery in a very short time.

    simply took the relay off and, in desperation, tapped it a few times on the engine and refitted it....perfect to this day. :thumb:

    chances are removing and refitting cleaned a bad spade terminal. :Doh:
     
  7. johnp10

    johnp10 Funster

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    Just had a thought, and it didnt even hurt!
    When I switch the fridge 12v on with the engine running, the switch doesn't light up as the EHU one does in use.
    Is this pointing in the same general split relay direction, or is this a different relay?
    I've checked other threads on the forums, but none seem to answer the problem.

    You will have gathered by now...Techno muppet!
     
  8. pappajohn

    pappajohn Funster Life Member

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    usually is a pair of 30 or 40amp relay's, one for battery, one for fridge but yours sounds like it may be a single one.

    when you find the relay, determine which wires trigger the relay and TEMPORARILY bridge them with a short length of wire.

    does the fridge now work and the hab battery show 13.6v+ with the engine running.

    if it does, the relays buggered.

    dont forget to remove the 'bridge' wire after the check.


    Ooops...correction....find the two wires on the relay that feed the fridge/battery and bridge those, not the trigger wires.
     
  9. harryoxford2

    harryoxford2 Read Only Funster

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    Oh no....one more thing I havent got a clue about and didnt worry about....knowledge is a dangerous thing..im worried about me split relay recharge batteries either single or double...Im gonna try find it so I can bang it when the need comes....

    I do like your maintenance technique Papajohn
     
  10. scotjimland

    scotjimland Funster Life Member

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    First things first .... Check the 25A inline fuse between the alternator and the split charge relay ..
     
  11. johnp10

    johnp10 Funster

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    I had the multi meter out this morning.

    Prior to engine start:
    Engine battery 12.29 (low, probably through lack of use, but doing whats required of it).
    Hab battery 11.26 (up from 8.something last night).

    On engine start up:
    Hab battery dropped to 4.42 over about 10 seconds, still dropping when I switched engine off.

    After engine switch off:
    Hab battery climbed to 10.3 over about 10 seconds.

    Multi meter on engine battery:
    Before start up 12.29
    On start up immediate (seconds) climb to 14.8 then steady at that.

    Can I reasonably assume:
    Alternator ok?
    split relay ok?
    Hab battery knackered?
     
  12. johnp10

    johnp10 Funster

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    Bumped in the hope of further advice.
     
  13. Mixter

    Mixter Read Only Funster

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    Very handy advice im personaly following here, but how do you determine which are the correct relays to play with - or even where they are??

    (sorry for butting in).
     
  14. johnp10

    johnp10 Funster

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    Thanks for your advice, folks.
    Split charge relay as suggested.
    Replaced, now reading charge of 13.68 at the liesure battery.
    Just remains to be seen if any damage has been done to the battery itself through being so discharged.

    Mixter,
    Split relay should be near the vehicle battery, certainly between the alternator and the battery itself.
    Dont do as I did and look for a hefty bit of kit: it's just a simple relay, looks like any other.
    Luckily I have a converter's wiring diagram, so it was easy to find.
     
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