Cole Hersee Dial/Switch on firewall between engine and coach batteries

[luckyron1]

I used to know what this is but it's been 6 yrs since I last used it and there's
no mention of it in the LXI manual. I remember it has something to do with the
batteries. It has 4 positions, 3 of which are marked. The 12 O Clock position
says both; the 3 O Clock position says 2; the 6 O Clock position says off; and
the 9 O Clock position says 1.

It has been in the (#1)9 O Clock position for years and there have been no
issues with it that I can recall. We're about to put in 6 new AGM coach
batteries and I want to be ready for the installer. Can anyone explain what I
need to do with the switch? Anyone? Thanks.

2000 LXI in San Antonio