Battery cable sizing? Moving battery...

Charts

Nothing demonstrates hope better than fishing.
  • Aug 22, 2015
    279
    99
    San Diego
    Name
    Charts
    Boat
    arima sea explorer 16
    Just bought a pair of new group 27 size marine batteries for my 1990 Arima Sea Explorer 16 with a 90HP Tohatsu MD 90C2 outboard.

    Previous owner had both batteries (and the switch) under the starboard side area in the stern, but not in battery boxes. I bought battery boxes for my new pair.

    With the boxes, they don't fit well in there enough to close the wooden slat. The 'handles' sticking out of the battery boxes get in the way. I was thinking of just hacksawing off the handles...

    But then I was thinking that the batteries are pretty heavy and maybe it makes more sense to move one to the port side for balancing. Plus, it might be nice to have them separated for redundancy in case of some kind of disaster in one of the storage areas. Turned sideways, there'd be plenty of room for one battery and its box under each.

    I'd need to buy new battery cables for the one on the port side. I'm thinking it'd be a 10ft run (7'6" beam, plus a couple of feet for routing).

    Trying to figure out the battery cable size I'd need. Not sure what the starting amperage requirements are.

    The current cable has written on it: SAE J1127 SGT Type 2 60V & SAE J378 50V 4 GA 105 C (220 F) dry

    I'm not sure if that means it's AWG 4? And not sure if I need bigger for the longer run.

    Ideas?
     
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    Charts

    Nothing demonstrates hope better than fishing.
  • Aug 22, 2015
    279
    99
    San Diego
    Name
    Charts
    Boat
    arima sea explorer 16
    You will need your starter amperage

    I don't know how to find this. TheTohatsu service manual doesn't seem to have it. Googling it finds likes of people asking the same question but answers from Tohatsu that I've been able to find. Maybe my search skills are weak.
     
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    samotlietuvis

    Newbie
    Feb 2, 2019
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    Palmdale, CA
    Name
    Tomas
    Boat
    Sea Hunt Victory 207
    AWG # 1 will work unless you have long run, then AWG #0. Find voltage drop versus length table.
     
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    kindafishy

    I Post A Lot But I Can't Edit This
    Jul 21, 2010
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    hemet/ca/riverside
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    SCOTT
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    bayliner cierra express 2452 "RYLEE'S WAVE RYDER"
    Interesting, please explain.
    the run is from the battery, to the load, and back to the battery. or so i was told.

    1594425761218.png
     
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    Mike_I

    I Should Upgrade My Account
    May 19, 2006
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    Irvine
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    Mike_I
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    Cabo 216 First Love
    current flows from the battery to the motor back to the battery. Those crazy little electrons need a complete circuit to flow. If you have a ten foot run from the battery to the motor the motor won't run until you complete the circuit with the other 10 foot run back to the battery. The total length may be a little shorter if the negative side of the motor is connected to a chassis ground instead of going back to the battery but it's best to round up.


    Interesting, please explain.
     
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    gecsr1

    Plain Jane Rods...Hobby Rod Builder
    Jul 15, 2005
    14,674
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    Poway Ca
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    Gary
    Boat
    No Boat Now
    current flows from the battery to the motor back to the battery. Those crazy little electrons need a complete circuit to flow. If you have a ten foot run from the battery to the motor the motor won't run until you complete the circuit with the other 10 foot run back to the battery.
    yes explain do a diagram.....please
     
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    sickcat

    Silverback
    Aug 5, 2003
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    Kerry
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    Yellow spot
    +1 on Mike's idea to put a ground buss in the center and run each battery and the engine to it.

    If it were mine I would run #2 cable. #1 cable would be overkill. #0 is way overkill.
     
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