It's very possible a PO added the four 6v coach batteries and the chassis battery is elsewhere. Check in the engine area, under the steps or in other compartments.
I cant tell by the picture, but it is possible (but unlikely) a PO used two 6v batteries for the chassis and two for the coach.
John & Clare Lyon
2007 43.5' Monaco Dynasty Palace III (All Electric)
Towd: 2011 Chevy Equinox