How to set up batteries

Discussion in 'Boat Modification Journal' started by jdbuckshot, May 29, 2008.

  1. jdbuckshot

    jdbuckshot New Member

    I plan on using three 12v batteries, one for starting, one for trolling, and one for accessories. Is this over board? accessories will include LED deck lighting, 4 80 watt KC lights. VHF radio, and a cd player. The spot lights will not be used much. Can i just run these items off of the cranking battery? or is there a way to hook to alternator up to an additonal battery?
  2. SkipEye

    SkipEye Well-Known Member

    Winfield, MO
    I would leave your cranking battery dedicated to just starting the motor. It's no fun turning the key and finding out your accessories have left you the inability to restart after a long day (or night) fishing. Then you have to pull out the rope, take the cowl off, probably find a screwdriver to remove a cover from the flywheel and wrap the rope and pull. Not fun, and dangerous if you need to make a quick exit.

    They make battery isolation switches that would allow you to charge either battery from the motor but the easiest way is to just buy a dual bank onboard charger for your two aux batteries and let the motor charge the cranking batt. Three batteries are not excessive and most likely your trolling motor will be 24 volts anyway in which case you would need three batteries. Spend the $100.00 bucks or so and get the onboard charger, a tried and true system that works.

    Just my opinion.


  3. crazy

    crazy New Member

    Kansas CIty, MO
    I have 3 battery's on my boat. Been thinking of getting a perko switch though. That way the motor can charge the other 2. Who likes having to go use something and there battery is dead. Would rather have it charge while the motor is running.
  4. Mr.T

    Mr.T Active Member

    If you've got a good quality starting battery and an alternator that does a good job of charging it and if you run the boat long enough and often enough to let it charge the battery, you can probably get by running most of your accessories from the starting battery.

    The spot lights and any other high-current accessories should probably be run from the trolling motor battery - and you should get a large capacity battery for that purpose, not the smallest and cheapest Wally World special you can find.

    The VHF radio and CD player and LED lighting don't draw much current (the VHF will pull a lot of current when you're transmitting, but how often is that?).

    I run most of the onboard accessories from my starting battery, but I've also wired in a second fuse block that is powered frm one of the trolling motor batteries. Power to the second block is switched through a relay driven off of the main block - so when the master switch is off, both blocks are dead.