Isolating house loads for dual battery setup

[Wakeboarder141]

1990 Bayliner Capri 4.3 Merc

I am hoping to get some help with wiring this Blue Sea Add a Battery Kit into my boat. I understand the wiring instructions for the ACR, but I am trying to isolate all the house loads to only be powered from my house battery. I currently only have a single battery with just one power lead that runs from the battery into a wire loom and becomes hard to trace. I don't quite understand all of the wiring from the starter, coil, etc. There is an existing fuse panel under the drivers dash that I am hoping I can have just powered off the house battery so only starting loads can get pulled from the starting battery side. My problem is I can't figure out where that power lead that feeds the fuse panel originates to split it off from the starting circuit. If I need to wire in a new fuse panel I can, but I was thinking that using the existing fuse panel would be the easiest option. The house battery would mainly be running a stereo, amp, subwoofer, lights, etc.

 

[demarko210]

I am going through the same. I plan on hooking up dual batteries so i decided to rewire the entire boat. I recommend drawing out your electrical needs on paper and plan accordingly.
I ordered 2 12-bank fuse panels as i will get rid of those inline fuses that are hard to trace if one goes out when on the water. I orderd the add a battery kit and a dual tray for 28 series batteries. 20ft of 6 guage wire to run power to console/cabin. Then i will start to rewire items one by one. My only issues is there is not alot of space in the transom area for me to hook the 2 batteries up but they will fit.

 

[Wakeboarder141]

I am going through the same. I plan on hooking up dual batteries so i decided to rewire the entire boat. I recommend drawing out your electrical needs on paper and plan accordingly.
I ordered 2 12-bank fuse panels as i will get rid of those inline fuses that are hard to trace if one goes out when on the water. I orderd the add a battery kit and a dual tray for 28 series batteries. 20ft of 6 guage wire to run power to console/cabin. Then i will start to rewire items one by one. My only issues is there is not alot of space in the transom area for me to hook the 2 batteries up but they will fit.

Mine is all pretty much wired as all of my house loads are already connected to the fuse panel. I just can't seem to figure out where the wire that feeds the fuse panel splits off in the engine compartment so I can relocate it to the house battery.

 

[dingbat]

I just can't seem to figure out where the wire that feeds the fuse panel splits off in the engine compartment so I can relocate it to the house battery.

The ignition is typically powered via the battery cable. A lot of times the “house” load is tied directly at the battery terminal by a secondary wire

Bear in mind that should your house battery take a dump, you can’t use the starting battery to power the “house”. If you have critical needs wired to house you need a backup plan

With that in mind, I run two networked MFD to support critical navigation functions, i.e Chart plotter, sonar and radar. One is wired to Start, the other to House

A bit overkill for most but gives you something to think about for when push comes to shove.

 

[sam am I]

I don't use an ACR or the "ON, OFF, Combine" switch BUT, I do have multi battery's and a battery management/iso setup similar to it. That said, a backup plan as DB said is a must, there are few ways to do this, his is a good one esp if he/your offshore.

However, beings I just have one Sonar, one VHF, one Bilge pump and one set of Nav lights, etc, I use a Schottky "OR'ing diode. (Schottky, Vf = 0.3V @ 10A)

With it installed as shown below, the house side CAN'T draw from the start side and the start side CAN'T draw from the house side, the two systems stay totally isolated at all times! BUT, the critical nav leg/path can always automatically draw from both sides.

If then for example, you kill the house batt flat(and shouldn't "combine" a flat battery with your safely kept full battery) , the diode automatically (steers the current to the highest potential) uses current from the start batt and vice versa.

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Just note that any load, even 1 amp for example, left on long enough will equally kill BOTH batt's.

 

[Wakeboarder141]

The only critical load I have would be the starter. This is simply an onshore runabout/bass fishing boat. The ACR and switch does have the "combine" function if I needed to use it in an emergency to start the boat. The only real issue for me is trying to figure out where in the wire loom is the best place to disconnect the wire that feeds the fuse panel so I can run that straight to the house battery. Currently there is only one wire from the starting battery that goes somewhere into the engine compartment, and another wire that runs to the trim motor. My thinking is that the fuse panel seems to only power house loads, and all the starting/ignition wires are run separately.