Battery Selector Switch

[chesapeake724]

The PO of my last boat mounted the Guest dual-battery switch exposed on the starboard side of the transom, between the gunnel and splashwell. No problems with it being outside.

I just added a second battery to my boat and decided to go with a battery combiner instead of a dual-battery switch. There's a scheit load of posts between the battery combiner vs. battery isolator fans on THT, but I went with the combiner. Basically, the two batteries are two independent circuits, but when a charging voltage is detected from the engine, the combiner connects the batteries in parallel so the batteries get charged. I won't get into the pros and cons, but I went with this setup for its elegance of simplicity.