Mike Wills used the 2 motor cycle battery trick for the RV4.

The situation is you use both batteries for starting
and then, after a short while for charging purposes, you switch
one off for flying.

The other is kept in reserve in case of alternator or battery
failures. This probably puts a glitch on the main power bus when the
back up battery is switch in or out.

I will add a choke and large capacitor on the main bus to smooth
the glitch.

Paul




You do not need two batteries for the starter, one battery works just fine.
I have been doing it for a few years now and as you know sometimes it gets
cold up here.

Rino Lacombe

What is the ampere hour rating on your batteries Rino?
The one I am looking at is only 28 Amp/Hour

Paul Lamar