Choosing The Right Batteries—HELP!

Discussion in 'General Discussion' started by Sundancer280, May 16, 2022.

  1. Sundancer280

    Sundancer280 New Member

    25
    Sep 7, 2021
    2005 Sea Ray 280 Sundancer Twin 4.7 Mercury Engines
    4.7 Mercury Twin Engines
    Good afternoon fellow boaters!

    Just need some advice—so my 2005 Sundance 280 4.3L’s has this problem of either having one of the engines shut off a few mins after I start it up, or an engine not kick on at all (Yesterday went out on the lake, shut it off, and then had to drive back with one engine because the other wouldn’t kick on even though it ran fine for an hour). Sometimes I’ll have to rev the engines as I’m kicking it on to give it some power so it doesn’t shut off. I’m guessing this is a battery issue. So I came to get some new batteries, and I realized that I have 3. My guess is one starting battery and two batteries (I think they’re called full cycle or something like that). However the lady at West Marine told me that the batteries come in different families…24, 27, etc. My boat has a starting battery, and then a 24 AND a 27. Is this the problem? Should both batteries be the same family? Also, would it be okay to just replace the 24 and 27 with new 27s? I have to go check what family the starting battery is, but I just know I have a mix of two for my other batteries and I’m starting to think that this may be the problem with one of our engines not kicking in (note: sometimes it’s the left engine and sometimes it’s the right).

    Do I just replace all batteries with new 27s? Or do I change them with families accordingly?
     

    Attached Files:

  2. swaterhouse

    swaterhouse Well-Known Member GOLD Sponsor

    969
    Jan 7, 2015
    Mattapoisett, MA
    2008 58 DB
    MAN CRM 900
    Hard to tell from your picture but yes it looks like two batteries are tied together in one bank and one in a separate bank. The two tied together should definitely be in the same group and type (i.e. lead acid or agm) and no reason not to have all three the same.

    That said I doubt the issue you described is battery related. I am not a gas mechanic nor do I pretend to be one, but this sounds more fuel/air related than battery.
     
  3. brewster16

    brewster16 Well-Known Member SILVER Sponsor

    Aug 9, 2009
    Long Beach Island, N.J.
    '07 44 Sundancer
    Twin Cummins QSC 8.3
    I agree...sounds more like fuel starvation.
     
  4. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    PA
    Various
    Various
    Definitely not your batteries, based on your description.

    Does this happen to both engines?

    Can you describe the issue better? Do the engines always run fine ABOVE idle speeds? Or is the issue only at idle speeds and/or trying to start the engine(s)?

    Does it "stumble" to start or runs rough in neutral?

    When is the last time you changed the fuel filters? Dump them into a glass jar to check fuel quality.

    BUT... just for your own sanity... check the voltage of the batteries at rest (nothing on and about 30 minutes after everything has been turned off) and with the engines running.
     
    Last edited: May 17, 2022

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