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Ideal battery & switch setup for twin outboards?

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  • Ideal battery & switch setup for twin outboards?

    I have twin 150 outboards and two batterys on a boat that goes moderately offshore (15-20 miles). Currently, each motor is wired to its own battery, there is no switch. One battery runs just the port engine. The other battery runs the stdb engine as well as the house load (through a cb) and also the bilge pumps - not an ideal setup. I'd like to install a switch so I can start/run either motor from either battery as well as run the house load from either. I've searched this site and found some great diagrams, but I haven't found on that shows 2 batteries and 2 engines. Would this setup be the same as for one engine? Would I just have both engines connected to the switch and effectively run them off one battery? Any thoughts on a good setup for me are much appreciated!

  • #2
    Re: Ideal battery & switch setup for twin outboards?

    I should add that the two batteries I have are both starting batteries (although they say dual use) and they are brand new.The house load is typical for a 24 footer - lights, vhs, gps, fishfinder, stereo, livewell pump etc.thanks


    • #3
      Re: Ideal battery & switch setup for twin outboards?

      You have got to think how you are going to charge the batteries. At the moment I am assuming hat one engine charges one battery and the other engine charges the other. What is wrong with your existing setup? I quite like the fact that running your house battery down still leaves you with a working starting battery that you cant accidently run low using accessories.


      • #4
        Re: Ideal battery & switch setup for twin outboards?

        I normally do not like to direct a person from one message board to another one but in this case I think it will do some real good for you and won't hurt the sponsor of this page at all.If you go over to The Hull Truth message board and then down to either the General Boating or Electronics subboard post your question again and ask for a fellow who calls himself "BirdMan" if he'd post his schematic for you.This fellow has put together an outstanding schematic for twin outboard wireing. It will show you exactly what to put where for a very well thought out and rational system. http://thehulltruth.net/category-view.asp Thom


        • #5
          Re: Ideal battery & switch setup for twin outboards?

          Thanks for in info, i'll follow up on your suggestion.After some more searching, I think the best setup is 2 batteries with a 1/2/both/off switch and an isolator made for 2 alternators and 2 batteries. I guess the idea is that both motors will charge both batteries. If one battery fails, both motors can still startthanks


          • #6
            Re: Ideal battery & switch setup for twin outboards?

            I have a 2 bat 2 motor 2 switch set up similar to the diagrams. I could be wrong but the schematics show 2 connections to the motor: starter and alternator. Is that always the set up two wires to the motor? I could swear there is only one + wire coming off the motor.


            • #7
              Re: Ideal battery & switch setup for twin outboards?

              FastKenny,That essentially describes Birdman's setup. His boat, which I believe is a 29' Scout, is heavily loaded with electronics but has adequate charging capacity (I believe he is running a pair of 225 hp. 4-stroke Yamahas). The schematic he has put together is so nice that about all you have to do is print it and laminate it as a wireing diagram for your boat - he even went so far as to color code it. The guy really did a nice job.Thom


              • #8
                Re: Ideal battery & switch setup for twin outboards?

                Did I miss something with Birdman’s diagram? I don’t see any way to disconnect the house bank form the electronics. If I am reading his drawing correctly, all that ‘house’ stuff, including the house battery bank, is piled onto the output post of the 1/2/Both switch. If so, there is no way to turn 'off' the house battery bank. This is no good!!!