I've had to revise my diagram a little, I realized that the output devices will happily accept 13.5v (Auto power standard) and that by regulating my scavenged source out to 13.5 it allows me to charge an 11.1v lipo to 12.6 (full charge) without any mucking about.
I have also included a Arduino, I wanted to include a micro computer eventually for monitoring etc but I realized that I would not be able to charge the main bank at the same time as using the auto/usb/multi charger. Doing it now will also allow me to easily add a small LCD screen.












