Batteries

Discussion in 'General Discussion' started by Larry33, Jun 24, 2018.

  1. Larry33

    Larry33 New Member

    4
    Apr 8, 2018
    1999 Sea Ray Sundancer 240
    5.7 Liter Mercruiser w/Bravo III Drive
    Hello. I recently purchased a 1999 240 Sundancer. Enjoying it very much. I have a question about the batteries. I have the switch with positions for battery 1, battery 2, or Both. However, in the engine compartment there are three batteries. I assume a previous owner added a battery. Not sure why. I don’t know a lot about batteries, but it appears these are wired on a “parallel” manner which apparently might increase run-time? Mainly, i’m Wondering how the third battery interacts with the battery switch e.g. is the third battery utilized only when the switch is in the Both position? Will the alternator charge all of the batteries? What is the most effective way to take advantage of having this extra battery if I’m away from shore power for a few days? Thanks for any help!
     
  2. bbwhitejr

    bbwhitejr Well-Known Member

    Apr 14, 2013
    Lake Lanier GA
    2007 44DB
    Cummins QSC 8.3s
    Most likely, your cranking battery is Battery 1 on the switch and the other 2 are wired in parallel and are on Battery 2. Need to figure that out to be sure. The two wired in parallel are your house batteries and give you twice the run time. They will act and you handle them like they were just one big battery. Fully charged and in good health, you should be able to stay on the hook for several days. Always change to the house batteries when you shut your engine down and save the cranking battery for nothing but started. When you move the switch to “Both” you have the power of all three batteries.

    Bennett
     
  3. Larry33

    Larry33 New Member

    4
    Apr 8, 2018
    1999 Sea Ray Sundancer 240
    5.7 Liter Mercruiser w/Bravo III Drive
    Thanks, Bennet! That would make sense. Except, I can start the boat in either switch position 1 or 2. If a previous owner had dedicated battery 1 as the “cranking” battery, I shouldn’t be able to start the boat in switch position 2, should I?
     
  4. Wylie_Tunes

    Wylie_Tunes Active Member

    519
    Oct 26, 2012
    Lake Wylie NC area
    N/A
    N/A
    This would be a properly wired setup. The dedication comes manually on your part. You crank on 1 and anchor on 2.
     
  5. wayne0

    wayne0 Member

    353
    May 4, 2014
    Newburyport, Ma.
    2000 340 Sundancer
    Twin 7.4 ltr.V-drives
    Yup!!
     

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