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Replacing Flooded Battery With AGM

Discussion in 'Luhrs Yacht' started by Hot Rod, Dec 21, 2009.

  1. Hot Rod

    Hot Rod New Member

    Joined:
    Dec 21, 2009
    Messages:
    32
    Location:
    Blue Water Point Marina, Oak Island, NC
  2. Hot Rod

    Hot Rod New Member

    Joined:
    Dec 21, 2009
    Messages:
    32
    Location:
    Blue Water Point Marina, Oak Island, NC
    I just received an answer from Blue Sea's technical department and thought their answer may be of interest to those following this thread. It is pasted below.

    Good morning, Mr. Bullock.

    The short answer is no, you can't do this. The slightly longer answer is that a battery switch is designed to turn on and off every day, and to be absolutely dependable in an emergency. A circuit breaker is simply not designed for that duty cycle. Additionally, that battery bank can produce more current than a 185-Series circuit breaker can handle in a dead short. At the very least, you'd be looking at a seriously degraded circuit breaker. The possibilities get much worse from there.

    You need a battery switch and an ANL fuse.

    Thank you for contacting Blue Sea Systems.

    Best regards,

    Erin Morey
    Technical Writer
    Blue Sea Systems
  3. Bill106

    Bill106 Senior Member

    Joined:
    Jan 9, 2010
    Messages:
    393
    Location:
    Beaufort NC
    Hot Rod,
    I just jumped to the end of this thread and may have missed things but I thought I'd add a little info.
    I have done several installs now with Deka grp 31 AGM's with CAT C32's and for house batteries. The CAT's are 24V so we use two in series but they have no problems whatsoever and we use 2 for house service, like you drew out so clearly. Your Yanmars are 12V (?), but one each should be more than fine.

    I just noticed you are located nearby and one of the oldest marine supply stores here in town sells the Deka group 31 AGM's for about the same price you mentioned for the flooded ones. I don't want to advertise for anyone but I be happy to give you the contact info if you'd like.
  4. Hot Rod

    Hot Rod New Member

    Joined:
    Dec 21, 2009
    Messages:
    32
    Location:
    Blue Water Point Marina, Oak Island, NC
    IMG_0402.JPG

    IMG_0404.JPG

    I am moving out of the study and explore phase and into the installation phase.

    Since my boat is in Oak Island, NC and I am in Newtown, PA, I have resorted to building a full size battery box to replicate the fiberglass seat box where the batteries will be installed once I get to NC. I got this idea of modeling from studying how the USS North Carolina WW II Battleship was constructed. Before any actual construction could proceed, a full size mockup of the actual room was constructed in a warehouse in the Brooklyn Navy Yard (http://www.battleshipnc.com/history/...?resultpage=5&). Once approved, the actual construction would begin. They were able to know that everything would fit and because of this, many parts could be ordered/constructed in advance. They moved from the beginning of the project to sea trials in an amazing 3 short years. That was very fast for a very complex battleship and just one of the reasons we won the war.

    Since CAD programming is cost prohibitive on my budget, I decided to follow the same full size mockup process. I constucted a plywood replica box to the actual seat box that the batteries will be installed. I will be mounting the ProNautic battery charger (you can see already mounted on the back wall of the box), ANL fuses holders, battery On/Off switch, Yandina battery vent-fan-control and Amp gauge shunt on the back wall. I was able to draw these in to scale on the back wall so that I could measure actual battery cable and battery charger cable lengths in advance to traveling to NC.

    I called this order in on Friday afternoon and expect to have cables by this Thursday. I can't wait to get my shipment and start the actual install.

    I have attached two photos of the box. You can see the vent cover on the front that provides protection for the muffin fan that will supply fresh cool air during the charging of the Deka 8D AGMs.

    I will supply more photos once I start getting the parts to fill up the battery box. :)
    Neil_N likes this.
  5. CharlieJ

    CharlieJ New Member

    Joined:
    Sep 30, 2008
    Messages:
    15
    Location:
    St. Petersburg, FL
    Suggest you put the isolation switch outside of the battery box to make it accessible in case of a casualty. If the batteries were catastrophically failing or the load was not responding to normal commands (windlass; bow thruster, etc.) the ability to shut off power quickly without removing cushions and panels would be very much appreciated after the fact.

    Charlie