I believe this start/isolation wire gets connected to the start relay on the wiring harness behind the control panel. Of course, I have no idea which relay and where to connect the wire. Does anyone know the answer to this question?
it attaches to the wire that activates the solenoid on the starter. When current is applied to this wire it activates the disconnect on the ACR, once the engine starts and the starter is disengaged, the ACR resumes normal functioning. Without knowing what kind of engine is in the boat and how the starting circuit is wired, it is difficult for anyone to be more specific and the place to connect the starter interrupt wiring.
It was my understanding that the intent for the circuit was to combine the two in the event that your starter battery gets drained and was to be wired with a temp on switch. I guess it would work for that also but I would have all of my electronics in the house bank and the starter only on the start battery which would eliminate the need as you described it.
Pretty much this is correct. The ACR allows the start battery to be charged from the house battery and prevents one battery for over discharging into the other. The Add A Battery kit adds a CP2 switch which has three positions, Off, On for each of 2 circuits (house and start) independently, and combined or paralleled.
The feature of the ACR that
@Souellette is inquiring about disables the ACR while starting. What can happen while starting is the start battery voltage drops quite a bit, the ACR sees this as the battery needing charging and allows a high discharge rate from the house bank. In a smallish house bank this can cause a significant drop in the house bank voltage which causes problems with electronics. Once the starter stops, there can be a voltage spike which can also cause havoc with the electronics.