On 11/26/2016 8:27 PM, wrote:
Unique wiring situation, I have studied the wiring diagram, and wiring
in the plane and not figured out a safe way to wire in batteries to
just the avionic side so that there would be no possibility of drawing
high current also for motor start. This would fry normal avionic
sized wires.

Ideally, it would be wired so you could feed the avionics from lithiums,
and then have the ability to save the main batteries for motor start,
but also use them as back up for avionics if the need occurred.

This sounds like an application for a battery isolator. Available in
the aircraft parts department at Home Depot. ;-)

http://www.homedepot.com/p/Cooper-Bu...-206793207-_-N