Charging system Question..

Discussion in 'Electrical Stuff' started by belliswood, Nov 17, 2017.

  1. belliswood

    belliswood Member

    Nov 21, 2011
    Colonial Beach, VA
    1996 370 SUNDANCER
    7.4 EFI 454
    I own a 1996 370 Sundancer. I replaced all the batteries 2016 however about half way thru this season my house batteries(2) (Starbard) would not charge up when on shore power. they would get some charge when out cruising but still not enough to start the engine. My house 12 volt works when hooked to shore power and my Port Battery works fine. Is it an issue with the charging system or have the batteries been discharged to low to recharge? The Batteries are Duracell 31 group Deep Cycle.

  2. hottoddie

    hottoddie Well-Known Member

    Jan 11, 2012
    Boston/Cape Cod
    1986 Sea Ray 390 EC
    Garmin 4212 Chartplotter
    Garmin 24 HD Radar
    Garmin 546s Plotter
    454 Crusaders
    Have you checked the water level in the batteries. If they are too low on water they will not accept a charge.
  3. PlayDate

    PlayDate Well-Known Member SILVER Sponsor

    Dec 25, 2006
    Washington DC
    1994 370 Express Cruiser
    454 Mercruisers
    The fact that they don't recharge on either shore power or the alternator points to a connection or battery problem. I would pull them and have them tested.
  4. Bt Doctur

    Bt Doctur Well-Known Member

    Aug 21, 2010
    New Jersey
    Ex SRV 240 Weekender twin
    in between
    Deep cycles are really not recommended for a starting battery ,I would have a dedicated starting battery and a dedicated house battery system.
    Check the water in the batteries and check the connections.
    Have the alt checked for proper operation
  5. Wylie_Tunes

    Wylie_Tunes Active Member

    Oct 26, 2012
    Lake Wylie NC area
    Id start with a testing them with a simple $20 DVOM at rest, with engine running and with shore charger (battery charger) plugged up. Much easier then pulling batteries and will tell you A LOT.
  6. Little Ducky

    Little Ducky Well-Known Member

    Jun 5, 2017
    Dickson, TN / Chattanooga, TN
    1998 290 Sundancer
    Twin EFI 5.0L w/Alphas
    Kohler 4kW
    Pretty easy to figure out with a volt meter with the batteries in the boat.

    How old is your charger?

    Does it have some status lights or a digital display telling what it's doing when on shore power?
  7. SloBurn

    SloBurn Member

    May 30, 2013
    Greenwood Lake, NY
    1994 270 Sundancer. 7.4L Merc. Tow with a 2006 Dodge RAM Hemi
    340 HP Merc 454 c.i.
    I don't think 2 would go bad at once, so check connections, water, etc. Get a volt meter, check at battery terminals-around 12.2-12.5 Volts engine not running, 13.5-13.8 engine running. Clean the battery terminals.
  8. belliswood

    belliswood Member

    Nov 21, 2011
    Colonial Beach, VA
    1996 370 SUNDANCER
    7.4 EFI 454
    Thank you everyone that responded. Brought the batteries home and put on battery charger. not charging up. both were house batteries so I guess there must have been a power outage at the marina that caused the batteries to be ran down so low they won't charge up again. will be buying new ones come spring..
  9. Boater420

    Boater420 Well-Known Member

    Mar 11, 2015
    Clearwater, FL
    '97 330 Sundancer
    Westerbeke 4.5BCG
    Twin Merc 454's
    There is something wrong with either the batteries or your charging system. There's no way new batteries should go dead in less than a year's time. In any event, bring the batteries back to where you purchased them and get a prorate on the new batteries.
  10. MickT

    MickT Member

    Aug 5, 2016
    australia - newcastle
    2006 sundancer 300
    twin mercruiser 5.0 mpi w/bravo III
    Many modern chargers will refuse to charge a battery that has run down too far - if you have a old "dumb" charger, it may breathe some life back into them.

    By being run down for an extended period, and too far for the on board charger to charge, the have been permanently damaged. But as they are house, not starting batteries, you may be able to get enough life back into them to go another season or two....
  11. Wylie_Tunes

    Wylie_Tunes Active Member

    Oct 26, 2012
    Lake Wylie NC area
    I kind of agree with Mick. I would not trust a charger "not charging up" unless I was watching it real-time on a digital diagnostic volt meter.

    Even if the batteries are toast, still leaves the question as to why. Dont install new batteries and think its all good. Still need to test the alternator output and charger output.
  12. Prosideus

    Prosideus Member PLATINUM Sponsor

    Jun 5, 2012
    Franklin, TN - Old Hickory Lake
    400 Sedan Bridge '96
    Cat 3116
    I have a 96 400DB and had to replace the charger. It fried a bank of batteries within one year. I replaced it when I put in new batteries and the next day one was very hot to the touch. I would not wait for issues with the charger to get worse. Would suggest eliminating an original charger as soon as possible on that year boat, if you haven't already.
  13. Russ Calasant

    Russ Calasant Active Member

    Dec 9, 2009
    East Greenwich, RI
    2001 480 DB
    CAT 3196
    Had a similar problem with a 97 370 and it was the charger. Called ProMariner and they gave me a reduced rate on a replacement, easy job too.

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