RE: Redundant battery setup
My friend built a simple circuit that switches from a 6V battery to a 4.8V battery if there is a failure of the 6V for whatever reason. Apparently it consists of just one or two diodes (might be more to it but I think thats the gist of it). If there is interest I can get the schematic from him and post it here. This is more of a protection against dead batteries as it does not duplicate plug ins to the receiver.