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    Battery bank wiring

    I'm looking to rewire my batteries this winter. Right now I've got a starter 12V, and two 6V batteries wired in series as a house. There's a Guest AC charger, and a Perko 4-way switch (off, 1, 2, all).

    The switch was installed by the PO in the cockpit, and my understanding is that the Perkos are not waterproof. So rather than move it into the engine compartment and leave a hole on the side of the cockpit, I was planning to replace it with a waterproof (IP66) Blue Sea Systems switch. I've also been having a problem with the voltage dropping and some of my electronics restarting when I start the engine. This is partly probably because the batteries need replacing (dunno how old they are, although they still test good). But mainly because I suspect the engine starter and house electronics are all wired through the Perko switch. That is, the starter and house electronics always draws power from the same battery(ies).

    Given all that, here's how I think the new battery setup should work. I'd appreciate if you folks could do some sanity checking since this is my first time doing any of this.
    • 1) Guest AC charger remains as is, directly wired to batteries. It's got two independent charging circuits, so suits both batteries well.
    • 2) Buy this Blue Sea kit: https://www.bluesea.com/products/765...ery_Kit_-_120A
    • 3) Wire Switch to battery banks, engine, and house electronics as diagrammed.
    • 4) Wire Automatic Charging Relay to both batteries.

    This creates the following scenarios:
    • Boat on trailer, charging via AC. The Guest charger charges both batteries directly.
    • Engine starting. Starter draws power from 12 V starter battery exclusively. Unless its voltage is too low in which case I move switch to Combine and also allows the starter to draw from the house batteries.
    • Underway. Engine alternator sends charge to 12 V starter battery as needed. ACR also sends charge to the house batteries as needed.
    • At sea, engine off, switch on. House electronics draw power from the house batteries.

    So this seems to accomplish my goals of isolating the starter from the house battery (except in emergencies), yet retaining the ability to start the engine off the house batteries in an emergency.

    The wiring diagram for the 2556 seems to indicate the house electronics draw their 12V power from the engine (that is, battery <=> engine <=> electronics), rather than the battery selector switch. Is this the case? Is this how it should be? Is there some advantage to this over wiring the house electronics to the battery switch?

    The dual circuit switch in the kit does not have alternator field disconnect. If someone switches it to Off while the engine is running, it could damage the alternator. I suppose this could be a good reason to move the switch into the engine compartment. But is there another way to prevent this that I don't know about? Or is glassing over the hole going to be the best solution?

    Also, any suggestions for ways to increase house battery capacity? Right now I've got two standard 6V golf cart batteries. But I can tell their voltage is beginning to get low after a full day of drift fishing with all the electronics and sonar on and the bait pump continuously running.

    Finally, Blue Sea Systems recommends installing the ACR directly between the two battery banks. This Amazon reviewer recommends installing the ACR on the engine side of the switch, instead of the battery side. That essentially powers off the ACR when the switch is in the Off position, eliminating the slow drain the ACR has on the batteries. Does anyone see a problem with this configuration, instead of the manufacturer recommended configuration?

    https://www.amazon.com/gp/customer-r...SIN=B000RZNP5K
    1994 2556, 350 MAG MPI Horizon, Bravo 2

    #2
    everything on your plan sounds good,
    I would keep the MBSS in the cockpit still... bluesea makes a battery switch with LOCKING KEY.
    Joon, Kathy, Jaden & Tristan
    Uniflite 42 AC, DD 671N
    93 3058 sold
    92 2855 (day boat)
    91 Fourwinns 205 (lake boat)
    Longbranch WA
    Life is Good

    Comment


      #3
      I also like having the battery switch easy to get to. Of course I have to go back about 50 years to when my folks had a ‘62 27’ Fairliner because everything I’ve had since then, including my 3818, has had the switch in the engine room. The locking switch is a good idea, it just depends where you are and use your boat. If the idea is to make it a bit difficult so that a thief moves on, that’s fine.
      Your separation plan is good, and one I’ve used. Be sure your automatic bilge pump switches are wired to the battery leads coming into the switch so that even when the switch has everything off, the bilge pump will still come on if needed. As to the condition of your batteries, this is going to sound strange, but have your battery charger tested. It may be thinking the batteries are at a full charge but it’s really only giving them a half load. Last winter I replaced the original charger on my boat and it really helped. On our last boat (twin engine) I had an 8D deep cycle and a 27 series starter battery. The only times the switches were not on “both” was when were anchored or at a dock without power. With that system I was good for two or three days. The biggest power draw was the refrigerator followed by the inverter (tv, hair dryer, espresso maker, microwave). On my 3818 I have a 27 series as a starter battery, 4 golf carts for the house and four more on a separate inverter only system, then a 24 for the generator. One of the benefits of that system is the refrigerator runs off of the inverter and leaves the house batteries alone extending the time available to be unplugged.
      As to the ACR, I’d follow the manufacturers instructions, but if it’s a piece of mind thing, call Blue Seas and ask them why should you do or not do what the reviewer said. The reviewer may be voicing a personal preference or may have a PhD in Marine Electrical Systems. The draw by the acr may be the proverbial fly spec in the pepper.
      P/C Pete
      Edmonds Yacht Club (Commodore 1993)
      1988 3818 "GLAUBEN”
      Hino EH700 175 Onan MDKD Genset
      1980 Encounter Sunbridge "Misty Blue" (Sold)
      MMSI 367770440
      1972 Chevrolet Nova Frame off Resto-mod in the garage
      Boating on the Salish Sea since 1948

      Comment


        #4
        Originally posted by Pcpete View Post
        As to the condition of your batteries, this is going to sound strange, but have your battery charger tested. It may be thinking the batteries are at a full charge but it’s really only giving them a half load.
        The charger is delivering a measured 14.6 V float voltage towards the end of its charge cycle, which is the correct voltage the manual specifies. After charging is finished, measuring the voltage from the batteries (no load, charger off) yields 13.2-13.3 Volts. So I believe they're getting a full charge.

        The voltage seems to drop to the low 12s or even high 11s after around 10-12 hours of use (with the engine occasionally running to move the boat). Also, the voltage under load seems to drop to this level after just a couple hours of use with the engine off. That's why I suspect the batteries are approaching EOL. They seem to have diminished capacity, and are experiencing a steep voltage drop at moderate load. Cranking the engine just exacerbates this. (I do keep an emergency NOCO lithium starting battery on board, so I'm not gonna be stranded if both battery banks die. This is more about annoyance at having my electronics die when I crank the engine.)
        1994 2556, 350 MAG MPI Horizon, Bravo 2

        Comment


          #5
          Our smaller cruisers are wired so all 12 volt needs are drawing from the selected battery bank via the MBSS. It's a simple system and works very good but does require the user to "manage" the MBSS but adding an ACR will let it "manage" itself so to speak.
          Heres a schematic that was posted many times by Rick it suggests the MBSS be moved out of the engine bay for quick easy access when it's needed. I think it's a great idea.
          your navigation electronics etc. can be run from an auxiliary fuse block connected to the house bank so they don't go blank upon start up.
          Click image for larger version  Name:	image.jpeg Views:	1 Size:	46.7 KB ID:	403202
          Dave
          Edmonds, WA
          "THE FIX"
          '93 2556 5.7 Bravo II 2.0:1 18 1/4x19 P
          (.030 over-Vortec top end-part closed cooled)
          The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
          Misc. projects thread
          https://www.baylinerownersclub.org/f...56-gctid789773

          Comment


            #6
            Solandri,

            I like your approach, which is dependent on the Dual-Circuit Plus switch AND the fact that you have a two output charger. This circuit will do everything as you stated. I think you can solve the "turning the Switch OFF when engine running" problem by wiring the STARTER to the OUTPUT side of the switch and the OUTPUT of the ALTERNATOR to the INPUT side of the switch. This way, the STARTER will be connected to the battery only when the switch is set to ON (or combine) whereas the Alternator output is wired directly to the battery (always) via the input side of the switch. The rectifier diodes in the alternator will prevent the battery from discharging through the alternator when engine is not running.

            Enjoy!
            Retired, computer expert / executive
            Bayliner 285 Cruiser / Mercruiser QSD 4.2L 320 HP Diesel
            Live in the Bay Area, CA, USA, boat in Turkey
            D-Marin @ Turgutreis in Bodrum/Turkey
            bdervisoglu8@gmail.com
            bulent@pacbell.net

            Comment


              #7
              That sounds similar to my old car battery charger. I have a car that is only drive on dry days, for good reason. I fought a weak battery for over a month looking for something on, disconnecting the battery to charge it, all the tricks. I finally bought a new battery charger and it spins like crazy’s, starts easily and just plain works better. Next, if you are going to be replacing any connectors, get the marine special shrink tube type. There’s a sealing glue in them that really seals fluids and moisture out of the connection. That type connector and shrink tube are now the ABYC standard. I’m by no means an expert on the rules, I’m having to update a bunch of the wiring on my boat and I’m passing what I’ve learned along the way.
              P/C Pete
              Edmonds Yacht Club (Commodore 1993)
              1988 3818 "GLAUBEN”
              Hino EH700 175 Onan MDKD Genset
              1980 Encounter Sunbridge "Misty Blue" (Sold)
              MMSI 367770440
              1972 Chevrolet Nova Frame off Resto-mod in the garage
              Boating on the Salish Sea since 1948

              Comment


                #8
                Being that you are using a 2 bank charger, one addition thing you should have in order for the charger to monitor each bank individually is a interrupt switch or relay on the ground wire of the ACR, this will prevent in from combining the 2 banks while the charger is on.
                Otherwise the charger will see all batteries as a single bank.

                https://www.bluesea.com/support/arti...r_Interference
                " WET EVER "
                1989 2459 TROPHY OFFSHORE 5.8L COBRA / SX
                mmsi 338108404
                mmsi 338124956
                "I started with nothing and still have most of it left"

                It's only a rock, get over it.

                Comment


                  #9
                  dktool is right about this and yet, I chose not to mention it because it complicates the installation. It is not just the addition of a relay that raises complexity but the fact that the relay coil is energized by 110v (or 220v_ AC power! This raises the question of where the relay should be installed. If you want to install it in the engine room then the relay needs to be installed inside an approved electrical box and make sure that it does not create a spark explosion issue, especially in a gasoline environment. If the relay is installed outside the engine compartment it still needs to be inside an enclosure to prevent accidental touching by humans/pets and the relay output has to be wired into the engine compartment to connect to the ACR to prevent it from engaging when external AC power is present.

                  In most cases, multi-output battery chargers are designed so that their outputs can be wired together (via the ACR) without a damage. This negates the advantage of the multi-output charger but is perfectly safe and fully functional. Thus, you may choose to exclude the relay.

                  Go either way,
                  Retired, computer expert / executive
                  Bayliner 285 Cruiser / Mercruiser QSD 4.2L 320 HP Diesel
                  Live in the Bay Area, CA, USA, boat in Turkey
                  D-Marin @ Turgutreis in Bodrum/Turkey
                  bdervisoglu8@gmail.com
                  bulent@pacbell.net

                  Comment


                    #10
                    Originally posted by MonteVista View Post
                    the fact that the relay coil is energized by 110v (or 220v_ AC power! This raises the question of where the relay should be installed. If you want to install it in the engine room then the relay needs to be installed inside an approved electrical box and make sure that it does not create a spark explosion issue, especially in a gasoline environment.
                    Just for the sake of discussing, would a NEMA 4X relay meet the environment concern you stated ?

                    " WET EVER "
                    1989 2459 TROPHY OFFSHORE 5.8L COBRA / SX
                    mmsi 338108404
                    mmsi 338124956
                    "I started with nothing and still have most of it left"

                    It's only a rock, get over it.

                    Comment


                      #11
                      I am not an expert on NEMA or NEMA 4X. My concern is to prevent flammable gas explosion due to potential sparking from a device, such as a relay. This would be referred to as "ignition protected" device and I don't know if NEMA 4X is ignition protected. Even inside a box, into which flammable fuel vapor would enter, a spark can cause a potential explosion.

                      Good luck!
                      Retired, computer expert / executive
                      Bayliner 285 Cruiser / Mercruiser QSD 4.2L 320 HP Diesel
                      Live in the Bay Area, CA, USA, boat in Turkey
                      D-Marin @ Turgutreis in Bodrum/Turkey
                      bdervisoglu8@gmail.com
                      bulent@pacbell.net

                      Comment


                        #12
                        a schematic that was posted many times by Rick is good, but IMO it is safest practice to connect the B+ outputs from the battery charger to each battery, or battery bank. Also to place a properly rated fuse in each B+ conductor as close to its connection to the battery B+ terminal as possible.
                        ABYC E-9.10 Each ungrounded conductor to a battery charger, alternator or other charging source
                        shall be provided with overcurrent protection within a distance of 7" to the battery.
                        Joon, Kathy, Jaden & Tristan
                        Uniflite 42 AC, DD 671N
                        93 3058 sold
                        92 2855 (day boat)
                        91 Fourwinns 205 (lake boat)
                        Longbranch WA
                        Life is Good

                        Comment

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