About the updated backup battery charger on IFI website:
http://www.ifirobotics.com/docs/firs...up-charger.pdf
Its better, the RC controller is connected right after the regulator now. The RC is still running off the 8.7V zener instead of the regulator though (although through the 43 ohm resistor). I think R1 could be removed. Let the battery charge off the output of the regulator. The Zener D2 could be left to protect the batery in case the regulator shorts outs. This would also take care of the discharge problem. when 12V is off.
I like how the manual highly recommends it, but IFI now says "use at your own risk".
Brian