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Port engine only starts when I parallel

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    Port engine only starts when I parallel

    I have a 2000 3988 I purchased recently. Last week the port engine failed to start unless I parallel the batteries. However, when I use a volt meter, all batteries look fine. Any tips?

    Voltmeter is not a good indication of battery cranking capacity.

    I am assuming things were normal for a while and this problem recently developed.

    How old are the batteries?

    Are they sealed or can the cell caps be removed?

    The questionable battery needs to be properly load tested..............the other one for good measure as well.

    Any traditional wet cell battery in a boat application is on the downhill side of life after about 36-48 months.

    If any battery has been flat dead even once, that substantially shortens life.

    I don't know the details of the wiring of your boat, but it may also be possible that a cable is going bad.

    Do have a hand held meter and do you know how to use it for voltage testing?
    Present Boat- 2018 VR5 4.5/200hp Mercruiser
    Last Boat- 1998 Capri 1950CL 3.0 Mercruiser


    • Stargazer
      Stargazer commented
      Editing a comment
      You’re probably right, I should just replace them. Thank you for the response

    Remove cables from Start Batteries and use a "Load Tester" might even find that your multi meter will show a week battery......What are the Start Batteries ??. I would also check the date on them,I wouldn't think that they are original,if so need replacing anyway.
    Brad & Sharon
    Lady Jake
    1985 4550 EH 700TI /Twin Disc 502
    Anacortes/La Conner, Wa.