engine battery drain

Discussion in 'American RV's' started by nahnotme, Jan 21, 2010.

  1. nahnotme

    nahnotme Read Only Funster

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    Over the last year my RV has begun to start less and less frequent as it should.
    I have to get the jump leads out to start, using the leisure batteries as even the auxilary MOM switch doesnt usually work.
    I have been told the battery is OK, its a 70ah. though Mr RAC said this seems small for a 7.4l petrol engine.
    Some one looked at it and said something is draining it, I have even bought a little solar panel to plug into the cigarette lighter as I thought it might be the alarm/immobiliser, though this is rarely used as I have been almost static for a few months.
    Any Ideas ? should I just buy a bigger battery, though due to space it wont be much bigger.
    As usual finances are tight so I'de rather avoid taking it to an auto electrician.
    I read on another thread that it may be to do with the way the starter motor is earthed, but surelly if winnebago have been making RVs for so long something like this wouldnt be a design fault...or would it ?
     
  2. savantuk

    savantuk Read Only Funster

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    The battery really does have a low AH capacity, and it really will have to be in top notch condition and be fully charged to fire up a big engine, particularly in winter when the oil is thick, and the plug heaters have to work so hard.

    I'm not an auto electrician, but I do think you are asking too much from a small battery.
     
  3. Wildman

    Wildman Read Only Funster

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    the first thing to do is establish how much current is being drawn from the battery.
    what is drawing it or is it down to poor battery condition, internal losses etc.
    How much is the solar panel putting in. (next to nowt at this time of year I'll bet)
    how often do you run the engine.
    Is the alternator charging properly.
    All of these things can be checked with a simple multi-meter, every motorhomer should have one and know how to use it.
     
  4. The Wallace

    The Wallace Read Only Funster

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    The reference to earth problems do not refer to the initial build or design no matter who makes the beast but to the condition of the earth wire and its terminals after a few years of getting wet.
    Many starting problems can be traced to corrosion of the earth strap itself or to corrosion of its terminals (or both). A quick look and tug on the earth should give you some idea of its condition - if in doubt - change it !
    Your battery may be at the end of its useful life if it has been allowed to run down a few times.
    IF your MOM ? switch engages a relay to link the batteries it will not work if there is not enough power in the batteries to engage it.
    IF 70Ah was big enough for years then why change it to a bigger one now?

    Good luck!
     
  5. pappajohn

    pappajohn Funster Life Member

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    following on from 'the wallace' post...if the battery earth wire is connected to any metal bodywork (can you trace it ?, not sure with it being an A class rv) then somewhere there will be a seperate earth strap from body to engine or gearbox.
    this is usually just an unsheathed braided wire strap and they do rot.

    dont just visually check it...pull on it hard and waggle it around.
     
    Last edited: Jan 21, 2010
  6. Geo

    Geo Trader - Funster

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    You can rule out earth fault the next time you have the problem, by make a good earth connection using your one of your jump leads from starter to chassis and try to start engine, if any improvement is made, then look at fixing or replacing the permanent earth, if no better then your earth is good anyway

    It could be your Emergency Start Relay causing the drain if faulty

    Jumping from your house batteries on a regular basis will certainly damage those as well if they are "proper " Leisure type
    Geo
     
  7. John H

    John H Read Only Funster

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    It could also be the starter and not the battery, if you've had the battery tested and its ok you may have a lazy starter motor.

    John
     
  8. Dodgey

    Dodgey Funster

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    Battery sounds small and the description of getting worse sounds like end of life. If the MOM isn't doing much, how are you leasure batteries, if they are on thier way that's that.
    As to drain, I guess you have a switch left of dash for the radio power source, ie engine or leasure? Needless to say if it's drawing from the engine battery, even if you are not using it (standby/memory retention etc) there will be a draw likely beyond the capacity of you solar widget.
    Siunds like full battery check and likely replacment.

    Don't know about others but, for the engine battery go to a Yank specialist. We needed one for the old Dodge, and frankley could do with new on our Winne, and the equivalent Euro batteries seems enormous size wise agains the correct American ones. 7.4 litre big block is a lot of motor to spin!
     
  9. buttons

    buttons Funster

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    If the battery is over 3 years old or it has run flat a couple of times then replace it, Cheap as chips. There is no point in testing other components if the battery is on its last legs. Testing a >3year old battery could give you a false confidence.
    :thumb::cry:
     
  10. nahnotme

    nahnotme Read Only Funster

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    Radio is always on auxillary (leisure batteries) and sorry Buttons but ive been quoted £78 for a 95ah / 680 cold cranking battery, which is slightly bigger than what was there which certainly isnt cheap as chips !
    Anyway ive got someone to have a look at it sunday so will pass all your thoughts on.
    I have 2x110ah "proper" leisure batteries 1X 110ah and a 85ah "non proper" leisure batteries. I know there is a minimal loss as they arnt all the same size and age but ive been told by several people both on this forum and the battery wholesaler who quoted me that this should make very little difference.
     

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