Isolate House Power From Start Power

[dingbat]

Sure, just flip the battery switch to BOTH. With a two battery setup isolated via ACR, I suppose much of this is academic. The real advantage of that kind of system is that if one battery is drained, for whatever reason, the second battery is isolated until you choose to combine.

The starting battery is primary and isolated in the system. The house is the slave.

The system works well, but there is no guarantee as to the condition of the house battery at any given point.

An under charged or failing primary battery may never reach the voltage threshold to open the ACR to charge battery 2 and you would never know it.

The first sign of my impending problem was my sonar display acting up. Shortly there after my tach started acting up.

Combined battery 2 with battery 1, which I later found out was shorted internally. Tow Boat shows up 3 hours later to tow us back from 17 miles offshore.

Cost me a battery, a voltage regulator and 4 hours of labor to install and wire a remote indicator lamp at the helm to monitor ACR combine status.

I have since installed a second volt meter to monitor each battery independently as well

Learned my lesson on combining batteries of unknown condition as well

 

[Boilers2000]

I had the same thought about adding a 2nd Volt meter. One more question...Mercruiser Service Manual 7 shows the ignition switch wiring, and it shows a purple wire in the B position (which I thought meant battery). The purple wire goes to each of the gauges and then into the wiring harness and then back the the excitation lead and ignition coil back in engine compartment. Seem's odd. I would have expected the red/purple to be the B, Purple to be ignition circuit, and the red/yellow to be the start circuit. I'm going to try to look at it tonight to see if the actual wiring matches.

 

[Boilers2000]

Went and actually looked, 12v from the battery is connected to B, purple is on the A, and yel/red is to S. That seems to make more sense. New discovery there are two extra wires to the tach that are mounted under the fuse panel, didn't have screwdriver to take off fuse panel, but no idea what the are for. One I think is connected to the sender terminal and 1 to the batt terminal, didn't have time to trace them.

 

[Boilers2000]

Last question....from the positive battery terminal I need two wires, 1 to the ACR and is supposed to be fused, and one to the switch unused. What is the easiest way to do that. I found terminal mount fuse blocks...can I put the unused with the fuse block that goes on the battery terminal and the used the fused side for the wire that is supposed to be fused? Or do i get the double and not use a fuse on one of them Is? Is there another solution that I'm over looking? Thanks in advance.

 

[dingbat]

Last question....from the positive battery terminal I need two wires, 1 to the ACR and is supposed to be fused, and one to the switch unused. What is the easiest way to do that. I found terminal mount fuse blocks...can I put the unused with the fuse block that goes on the battery terminal and the used the fused side for the wire that is supposed to be fused? Or do i get the double and not use a fuse on one of them Is? Is there another solution that I'm over looking? Thanks in advance.

I have regular battery cables running from the batteries to the On-Off-Combine switch.

I made up two cables (#4) with in-line fuses to run between each battery and the ACR.

If I had to do it over again, I would forgo the in-line fuses and go with these. I used them to tap a line off the truck battery to run a line to the back of the truck to power the electric winch. Clean install and worked great
https://www.bluesea.com/products/519...k_-_30_to_300A


If you need to have (custom) cables made up, this is a good place to have it done.
http://www.genuinedealz.com/marine-w...-battery-cable

 

[Boilers2000]

Thanks for the input and the website for custom cables, a made cable from there is cheaper than the wire itself from west marine. Also those fuses are what I was leaning towards, so glad to hear that is what you would use if you did it again. Thanks for all the help and advice...now to figure out where to squeeze a 2nd battery in.