I/O Batteries

Discussion in 'Boating and Boat Rigging' started by fishgtbay, May 9, 2018.

  1. fishgtbay


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    OK, here's the situation, I have a Sylvan offshore with a 3.0 and a 9.9 merc kicker manual start without altenator, also have Perko battery switch. When I bought this boat 2+ yrs ago it came with a 24 and a 27 series batteries the 24 is a deep cycle and 27 is a starting bat. In the past we would set the perko on both batteries to start and drive to location then use kicker and fish, using the downriggers up/down for 4-5 hours then when done touch key and she would start right up, Saturday not enough to start her up....So with that said my question is two fold 1. Is it right to have a 24 and a 27 or should they both be 27 class batteries?. 2. Should they both be starting batteries or keep it the same one being deep cycle and one starting? While trolling the electronics I have on would be fishfinder, x-4 fishhawk, and raising and lowering riggers, I realize every hour or so I should start I/O for 10 min or so to charge batteries depending on how much I raise riggers.....Thanks for you your input
  2. ebijack

    ebijack Premium Member

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    Anytime you hook batteries together, the weaker one will pull/draw down the stronger battery.
    I'd guess at least one of your batteries is getting old/weak. Causing your problem.
    Check both batteries voltage with a digital meter. Not while charging. If you are checking the battery condition. A fully charged, soaked 12V battery should maintain at least 12.54 volts with no charger being used. You do not have to unhook the on board charger, just unplug it a few hours/days before checking the battery.
    The deep cycle should be used for the downriggers. Starting battery for starting. How many amp/hrs etc is up to you.
    I would suggest selecting "both" batteries to charge when the engine is running. But the riggers would only be able to run from the deep cycle. Not draw power from the starting. If that makes sense.
    You should not have to run the engine every hour. Your batteries are weak.