Bill,

It is the Z-14 schematic from Bob Nuckolls book The Aero Electric Connection.  See www.aeroelectric.com/articles/Rev11/AppZ_R11C.pdf  Print out the two halves of Z-14 and tape them together and it will make a lot more sense.  It uses three contactors, a main battery contactor, an aux. battery contactor, and a crossfeed contactor.  Each is controlled from an S700-2-10 OFF/ON/ON switch on the panel.  What is neat is that the same switch that operates the contactor also operates the respective alternator field lead.   This saves space on the panel.  There is a third S700-2-5 ON/OFF/(ON) switch that operates the x-feed contactor (down position) as well as the starter contactor (up position), saving more panel space.  Credit for the design goes to Bob Nuckolls. 

 

Mark