w203 battery

Discussion in 'Electronics' started by dav007, May 11, 2015.

  1. dav007

    dav007 Hardcore MB Enthusiast

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    hi there seem to be haveing a problem with starting in the morning bit strange as i when i plug the house car chager on th charges for a min then states full chagered so when it happened again the checked the volts at the battery and it showed 12.4 volts so the battery charger is only charging it an extra 0.3 in to the battery

    is this right that .3 of a volt would not turn over the car
     
  2. OneForTheRoad

    OneForTheRoad Hardcore MB Enthusiast

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    Leave it on charge for a few hours . 8 amps if possible . Sounds like some of the cells are dodgy and not letting voltage through . A forced charge sometimes wakes them up . If you manage to get the battery to acept a charge . Leave it on 4 amps for 24 hours
     
  3. OP
    OP
    dav007

    dav007 Hardcore MB Enthusiast

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    hi my battery charger stops cos the battery is full charged
     
  4. Notwen

    Notwen Hardcore MB Enthusiast

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    Could be sulphated. Has it been allowed to stay discharged for extended periods ?
    12.4v is about 80% charged so should start, resting voltage ideally would be above 12.5v
    If possible, disconnect the battery from the car, allow to rest for a while, check the voltage. If it continues to fall it could be toward the end of it's working life.
    How old is it and does it have accessible cell caps?
     
  5. OP
    OP
    dav007

    dav007 Hardcore MB Enthusiast

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    only over night i use it almost dayley only had the car over a 1 year and a bit the guy i bought the car of said he changed it a year ago so we are looking at about 2 years a abit

    its a banner battery in the car it does have caps all levels are full
     
  6. OneForTheRoad

    OneForTheRoad Hardcore MB Enthusiast

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    the battery charger stops because it thinks the battery is fully charged. that's due to the battery being kaputtttttt !!!!!!..... try a not so clever charger and force a charge into it over a few hours , it might just kick it into life .
     
  7. Notwen

    Notwen Hardcore MB Enthusiast

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    I agree, it needs charge forcing in, if it is likely to recover.
    Ideally get a proper battery test done, with a Hydrometer and High rate discharge tester. You can simulate a HRD test by having the engine cranked for 10 seconds (ish)while you have a multi meter connected to the battery. Ideally the voltage will stay above 9v while cranking and then recover back up to around 12.5v when left to rest.
     
  8. nigel cross

    nigel cross Hardcore MB Enthusiast

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    A fully charged battery should read 13.2 volts, the problem could either be a duff cell,or your charger is up the swanney. But as it is going flat whilst being charged on the car, the battery is the likely fault. Battery's should last approx 6 years, so if this one was canged recently by the previous owner, it is either a cheapy or perhaps he was not telling you the whole truth.
     
  9. OP
    OP
    dav007

    dav007 Hardcore MB Enthusiast

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    thanks all will try and get it tested
     
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