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Thread: Battery type

  1. #1
    Join Date
    Feb 2019

    Default Battery type

    I have a 2018 Supra SL I put the two 27D that comes with boat in parallel and on bank 1. Added another large 4D battery on bank 2. This is how I have done it with my Seadoo 18ft utopia and also my 2007 malibu 23 lsv. This is what’s needed for a stereo this powerful so you can listen for a long time and not drain battery.

    I don’t think I left any electronics on and my bank 1 was dead. So started boat with bank 2.i think only the auto bilge is hard wired to battery. And I had no water in boat so don’t know what caused bank 1 to be dead unless I made a mistake and left battery switch on or if the alternator is broken,

    When I started boat with bank 2, voltage level is 14 volts which should imply the alternator works. However after running boat I switched to bank 1 and ran above 3500 rpms for an hour and shut off boat and bank 1 was only at like 10 volts . So maybe it takes longer than an hour to charge a dead battery and I understand an alternator shouldn’t be used to charge a dead battery or could damage alternator.

    I called Supra mechanic and was super disappointed . First off , all these boats have a popping noise thru audio when starting boat. Huge flaw and I know it’s caused by the huge voltage drop when starting these engines and they put in too small batteries . Mechanic called Supra and they said it was designed this way. So a $160k Boat was designed to give a huge pop to stereo ? What an idiotic response.

    Then mechanic says Supra says only 27D can Be used and non AGM. I asked why and he says cause this boat is very sensitive to voltages. Another idiotic response. So we spend $160k on boats and this is the technical service we get ? They should explain the technical reason.

    Since when does a boat not support AGM batteries ?

    And as long as you are not using alternator to charge dead battery , there’s no reason you should not be able to use a battery larger than 27D. And if so then what’s the technical explanation ?

    And the 4D resolves the audio popping issue which will eventually blow the speakers

    Any one out there that had the knowledge to comment ?

    Joe mama

  2. #2
    Join Date
    Jan 2017
    Katy, TX


    I'm not sure if it's in the Supra manual but it seems related to why you aren't supposed to run the boat in 1+2. Differences in battery banks could cause a voltage issue that can damage sensitive electronics.

    "Skier’s Choice installs a 4-position battery switch on any boat equipped with dual batteries. It is recommended that both batteries
    be fully charged between each use to insure they can deliver the electrical demands required for each outing. The purpose of our
    recommendation is to utilize one primary battery for all operational needs, and have the other as a backup if the primary battery
    discharges. This situation could occur if you run your accessories such as ballast or stereo for a long time, without running the
    boat. The dual battery setup is designed to create a redundant system allowing the user to have a backup battery. The switch
    must be in the “1” or “2” position to create the redundancy.
    The 4 positions available on the battery switch are: Off / 1 / 2 / 1&2. These choices indicate which battery is being used to power
    the boat and which battery is being charged by the engine’s alternator. We recommend using only position 1 or 2 while boating.
    Battery switch position “1&2” is available but not recommended as power will be drawn from both batteries and the alternator
    will have difficulties keeping both batteries charged simultaneously. It also creates a ground differentiation which in turn will
    create issues with sensitive electrical components such as
    the Vision screen. The only time you may need Position 1 &
    2 would be in an emergency situation where both batteries
    are low and need power from both to help start the engine."

    Sent from my Note9 using Tapatalk
    2017 Moomba Craz Surf MAX Edition
    Flow 2.0 Surf System w/ AutoWake™
    4,600 Lbs Ballast - Enzos + Lead
    Wet Sounds REV10s + REVO12-XXX

  3. #3
    Join Date
    May 2018


    Yeah the amp pop at start up is FN annoying.

    Sent from my iPhone using Tapatalk

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