I have 2 varios. I use 2 seperate flight computer running off of their
own GPS each on their own electrical system that are not connected. So
if my main system with 2 batteries go out. I will always have my
volkslogger and PDA to use to get home and more importantly score my
flight because it has its own battery. Plus that one has 2 flight
computer software's on it, so depending on my mood I can pick which one
I want.

Yes I charge all 3 batteries every night at contests.

If I was a big guy I would use the tail battery and have 4 batteries.

Redundancy is good when your trying to win.