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  1. #1
    Member
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    Jan 2017
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    Waverly, Iowa
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    2,655

    battery recommendation

    Currently I run my big motor, bilge and livewell pumps (that never get used), older lowrance unit, and new Helix 9 Mega unit all from my starting battery. I have 2 deep cycle batteries for the trolling motor. I don't have room for a 4th battery and I've been starting to have problems with my Helix 9 shutting off. I posted a question about it and was told my battery is not able to supply enough power for everything. I was told that because my big motor is a 1999 Mercury 175 EFI that I should not use an AGM battery (something about the stator). I would love to have lithium ion, but that's out of the question due to cost. What is a good battery that I could use as both a starting battery and a battery for my electronics?

  2. Member
    Join Date
    Apr 2014
    Location
    Rochester, ny
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    50
    #2
    Great question....I am having the same issues

  3. Electrical/Wiring/Trolling Motors Moderator CatFan's Avatar
    Join Date
    Jun 2004
    Location
    SW Indiana
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    26,089
    #3
    Following Mercury's recommendations, there is no good battery. They recommend against both AGMs and deep-cycles.

    The problem is that the charging systems were not intended to handle such heavy electronics use. You can overheat your regulators and cause them to fail.

    In reality, it's the heavy electrical load that is the problem, not the battery type. Running a cranking battery down until it is almost too low to crank the outboard is a bigger electrical load when recharging than a deep-cycle partially discharged by the same electrical use.

    My advice is to use a battery that does the job and ignore what Mercury says. You risk damage, but the alternative is to not use your equipment. To increase your odds, I'd make sure your regulators are not aftermarket products and inspect them and their wiring regularly for signs of overheating. Keep the batteries at full charge between trips to reduce the load on the system when you get to the lake.
    If you have integrity, nothing else matters. If you don't have integrity,
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  4. Member
    Join Date
    Apr 2009
    Location
    The lands of the former Republic of Texas
    Posts
    3,497
    #4
    No matter how much I run my lights, electronics and pumps, it has no effect on my outboard's main voltage regulator. That is because the outboard has its own dedicated cranking battery and all my console loads are on a house battery.

    I felt I didn't have room either for a house battery either...until I gave up a small storage compartment located next to my bilge area. With a sealed AGM, there is still room for certain items to be stored there.