Rob,

 

See the spreadsheet on my website, http://shannon.v8eaters.com/images/lancair/airplane_amp_draw_6.xls

 

This should give you an idea on a lot of components.  The strobes don’t draw a full 7A continuous, more like 4.0-4.5A.  The nav/pos lights are on the order of 2.75-3.00 amps.  I would suggest doing your power budget as I have for all aspects of flight (start, pre, taxi, climb, vfr, ifr, decent, taxi, batt only, glide).  This will allow you to design your system for all aspects of flight and have no surprises.

 

As far as alternator sizing, you want to size it so it can charge the battery, so some surplus is needed.  I would think 20% would more than suffice.

 

Alternator field is like 1A I believe.

 

Battery contactors are 0.8A.  Starter contactor is 5A.

 

Good luck.  You are going dual alt and dual batt right?