John little

Good morning Tomy, I won't get to the boat until tomorrow. But I can tell you that the center red lead goes to the ignition. The one on the right goes to the starter battery. This battery has an isolator to stop it draining. I am assuming the left lead goes to the lesure battery which has constant feed to the system. I found this out when I replaced the lesure battery with a new one. Diagram to follow.

Sorry Tony, one more question. From my photo, as yet I haven't checked with the multimeter. The center lead I've traced to ignition and left/right lead is to each battery. Is that right?

Thanks again Tony. I will go looking for a unit now. IOU

Thanks so much. The posts have really cleared things up for me. Tony do they fail?

Hi Folks, I have almost completed refurbishing a 27 foot Madeira canal cruiser. My final task is to completed the duel battery system but I don't know what the mechanism is that is currently installed. As she is ~1975 build its a very old system. Any help would be much appreciated. John