Of late I have been revisiting the idea of carrying a spare battery
. I'll detail my thoughts on that in a future post, but for now I have a question for you solar gurus...
The basic set-up is diagrammed in the schematic below. To maximize the versatility of this system, I would run both batteries through a four-position switch that would allow connection to either battery individually, or to both at the same time in what would be a parallel configuration. In this scenario, the pigtail to the spare battery would be no longer than a few feet.
If the solar is only connected directly to the main battery, is this set-up adequate to charge both batteries when in dual battery mode? Stated differently, is there a compelling reason why I should ensure the solar is connected directly to both batteries? In terms of electrical continuity I can't see a difference, but I suspect solar may have some other considerations that are beyond my current understanding.
Thanks in advance for any opinions or info.