I'm very similiar to David, with a pair of 680s. I modeled mine after Bill Watson. Both of us have Kitlog sites if you want to look up the details.

The only unusual part of my installation is that I'm using a VP/X Pro with dual batteries and dual alternators. Vertical Power recommends dual batteries or dual alternators. Some may think it's overkill, but I think I'm covering all my bases.

It's pretty easy to modify the battery tray to accomodate the additional space for the second 680. It's only a few inches larger than the tray provided in the kit.

bob

Here's how I did it for (2) 680s.
http://www.mykitlog.com/users/displa...g=43554&row=26

Aux Avionics Battery
 

II have a PC680 main battery, and a 7.5AH aux battery for powering ALL the avionics during engine start. The two batteries (both lead acid) are tied together during normal operations So both are equally charged - no diode drops), but automatically separate (via an under-voltage sense circuit driving a contactor) if the main bus voltage goes below 12 VDC, and during the time the engine starter is being engaged. Both batteries are used separately to power the essential avionics. I ALWAYS turn ALL avionics on prior to engine start, and none reset during engine start. I have manual switch operation of both battery contactors as well (OFF,AUTO, ON).. Both batteries are above the rudder pedals inside the cockpit, accessible via inspection covers on the front deck. If anyone is interested in the circuit design, I can post a PDF file of the schematic....

That sounds just about ideal.