Flat battery,nothing connected?

Discussion in 'Tech/Mech General' started by joner8888, Sep 5, 2013.

  1. joner8888

    joner8888 Read Only Funster

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    I fitted a new main battery 2 months ago and has been fine.
    Last week I checked to see if was all ok for the coming weekend trip--Click! no start!

    I used the on board EHU charging system for a day , worked fine after that all weekend.

    I returned back and disconnected one terminal on Sunday (in case of a discharge) and tried again earlier today --Click!

    How can a battery after working fine all weekend, then over 3 days go flat disconnected :Eeek:

    Took it back and argued for a replacement--got one ,but the battery centre said my old one was ok and needed charging only .

    The alternator seems to run everything ok and charges @ 15volts when driving (no light on) any ideas?:cry:
     
    Last edited: Sep 5, 2013
  2. Taran_Las

    Taran_Las Funster

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    Had a similar experience. Alternator charge is sufficient to extinguish dashboard light but a bad earth to gearbox inhibits full charge to battery. Would last OK for a weekend. Check all of your earths.
     
  3. cmcardle75

    cmcardle75 Read Only Funster

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    Get a digital multimeter. Measure the voltage across the battery, both when off and when the engine is running. Then come back with the figures.
     
  4. joner8888

    joner8888 Read Only Funster

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    Just tested---

    12.76v with key off
    14.60v running
    14.51v running with fridge and lights on
     
  5. cmcardle75

    cmcardle75 Read Only Funster

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    [1] = Pretty much fully charged
    [2] = Alternator producing lots of current
    [3] = Alternator producing lots of current, but fridge using some of it.

    Looks pretty good, no smoking guns, assuming you measured directly on the battery terminals themselves, not the cables. I suspect it is an intermittent bad connection somewhere, probably on the battery terminals.

    Perhaps removing cables from the battery terminals, a rub with wet and dry paper and replacing with a light smear of vaseline might be recommended. You could also do this to the alternator terminals, but make sure you disconnect the battery first unless you want your first welding lesson. Look our for frayed earth straps, too.
     
  6. joner8888

    joner8888 Read Only Funster

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    I have never noticed one of these before.
    It has insulation around the spade connection and only connects through the green knob thread.
    What is it for:Eeek:
     

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  7. TheBig1

    TheBig1 Funster Life Member

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    looks like a quick disconnect

    as mentioned before check all the charging cables including engine earth strap. if in doubt do a pull test. in other words give the cable a pull. it may be rotten inside and just disintegrate. seen this numerous times and it shows the charge isnt getting through all the time. if theyre solid, check for a good clean mechanical connection
     
  8. cmcardle75

    cmcardle75 Read Only Funster

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    It is a quick disconnect battery terminal. I fitted some to mine. A great little invention. However, they can cause intermittent connection problems if they aren't screwed on tight.

    Yours is so rusty it could easily cause the problem you are seeing. Disassemble it and give it a good sandpapering. The handwheel can be screwed off completely as a simple security measure. Do this to get to all the metal parts. Before reassembling, lightly coat in Vaseline to prevent it corroding again.
     
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