I havent been updating in a while due to lack of hardware and other projects going on (a VT100 terminal in an 68HC11 chip over a serial port that connects to a LCD screen and keyboard/mouse) however i have got more of an idea of how the project will work, basically i am going with power rails that i can connect to various inputs and outputs using mosfets or RELAYs (i like the idea of the power clicking over)

this should make it easy to connect the battries to a rail or enable/disable an output as well as quickly switch between supplies, if i use multiple rails then i can also link common devices together in a group and handel them in the same way

eg if power goes off on the input i can have only one rail that is automatically protected while the others switch off imediattlly, if i have the one rail then i have to detect the change and then switch over which will be on the order of several miliseconds and would cause a huge dip in the rails voltage which could reset some devices