Battery mistake?

Discussion in 'Electrical Stuff' started by crazy diver, Mar 4, 2021.

  1. crazy diver

    crazy diver Member

    Mar 1, 2019
    Boat is in Cape Coral Fla., Home is Windsor CO.
    2001 380 AC
    Cat 3126 350HP x 2
    My Battery lay out is as follows: 2 Batteries on Port side, 2 Batteries on Starboard side and 1 Battery for Generator. Without thinking things through and getting a discount...I replaced the 2 old wet cell port Batteries with 2 AGM's. The 2 wet cell Batteries on the starboard side are only about 16 months old and are good so i did not replace them. While on a recent cruise I noticed the Helm Amp gauges were reading different charging rates, one read 12 amps and the other 14 amps. Also while anchoring out my fridge would quit running on the 12 volt system after a couple hours.
    My questions are: Should I go ahead and replace the good wet cells with the AGM's so they all match or does it make any difference?
    Should one of the Batteries on each side be a cranking Battery and one a deep cycle Battery.
    Does the 12 volt house system draw from both Port and Starboard battery banks.
    Last edited: Mar 4, 2021
  2. bobeast

    bobeast Dance the Tide SILVER Sponsor

    Oct 22, 2017
    Isleton, CA
    2002 310DA
    350 MPI w/V-drives
    While cruising, you are charging from the alternators which have no concept of AGM vs. flooded. As long as all the batteries within a particular bank are the same, there should be no issue. When charging from shore power, the charge profile can be optimized based on battery type, but that depends on how smart your charger is. If it doesn't allow you to set the battery type on a per bank basis, you should use the charge profile for flooded batteries for your use case. This is not the optimal setting for AGM, but will be safer for your flooded bank.

    Typically Sea Ray, had the helm electronics on one bank, (port for my 310), and the "house" batteries are on the other. You can play around with your battery switches to ferret that out.

    I don't put a lot of credence on "dual-purpose" vs. "deep cycle", but I will say that all batteries in a given bank should be the same, so no you would not want a bank with one dual-purpose, and one deep-cycle. As long as your engines start up without excessive cranking, I think paralleled deep-cycles with sufficient CCA should be fine.

    All that said, I think the optimum setup would be all AGM with a modern smart charger capable of supplying an AGM specific profile to all banks. I'm partial to ProMariner's ProNautic series. I have the 1240P on my 310.
    crazy diver and PlayDate like this.
  3. crazy diver

    crazy diver Member

    Mar 1, 2019
    Boat is in Cape Coral Fla., Home is Windsor CO.
    2001 380 AC
    Cat 3126 350HP x 2
    Thank you for the response. I will take a look at the charger and see if it will fit my needs when I run all AGM's
  4. DB360

    DB360 Active Member

    Feb 25, 2010
    360 SUNDANCER 2004
    AXIOM 12 RV
    +1 on the ProNautic 1240P and our group 31 AGM's.

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