The Austro DA62s have:
Main Battery
2 x Alternators, each capable of supporting the entire electrical system.
Back up batteries for each ECU system (ie one left and one right).
The wiring schematic is rather busy (page 516 at
http://support.diamond-air.at/filead...1-complete.pdf) but clearly there is loads of redundancy. I think the Austro 42s are similar.