Catalina 350 International Association

I am in the process of adding an dedicated start battery (group 27) and combining the other two banks in parallel. At the same time installing a Blue Sea Add-A-Battery 7650 (includes Dual Circuit Plus Switch and SI-ACR automatic charging relay and start isolation). I will replace the original 1, 2, 1+2 switch with the Dual Circuit Plus Switch but the question I have is do I need to keep the original On/Off Engine DC Switch? Are there advantages to having it?

Thanks,
-Scott Sammons
2007 ¨Soixante¨ #444

It seems to me that isolating the engine, instruments and binnacle instrument panel from the house loads is a good idea. You can never be sure when a gremlin named Murphy may be skulking around, and if the house power goes down for some reason it's good to know the engine, etc., will still get you home. IMO. Also, it's really not hard to manage.

Ed

The power from the alternator travels via the starting circuit to the batteries I believe. It may go through the rotary switch.
Be conscious of battery chemistry.
If your going to someday put lithium for house bank I don’t think you can use the Blue sea.
A DC-DC charger between the starting/alternator/dedicated battery and house bank should keep the house bank isolated from starter circuit and allow alternator charging.
I was always concerned about draining the house bank and not being able to start engine.