<<<
 I agree with Jim, except I'll take that one step further on battery
 sizing.  I subscribe to the Bob N school of thought that an alternator
 failure shouldn't ruin your day or prevent you from going to your
 intended destination.  >>>

Your proposal reminds me of the stoy about the guy who took off from
somewhere in the deep South enroute to Texas in his light twin. Shortly after reaching
cruise altitude one engine failed. He feathered  the prop and continued
flying for another three hours before the second engine failed near his destination
from overheating-- the ensuing crash killed all aboard.  What you propose is
a violation of FAR 91.7, " The PIC shall discontinue the flight when
unairworthy mechanical, electrical or structural conditions occur." If the alternator
fails-- why did it fail? Is there a serious electrical short somehere you
should be concerned about-- slowly burning up insulation and anything else it
touches? Did the coupling or drive gear fail and an impending engine failure is
just around the corner ? Remember SwissAir Flight 111? It was just a little
electrical problem. Remember Alaska Air?-- just a little trim problem.

Jeff Edwards
LIVP N619SJ