The battery was intentionally removed from the screen in the AF-5000 generation for many different reasons. We have the two independent power inputs to provide the flexibility that you are looking for using pins 1 & 15 of the main harness for primary power input and backup power input on pin 6 of the 15 pin expansion harness. Given your senario I would recommend getting a secondary TCW backup battery that would power the AF-5000. In their manual is the wiring recommendations but if you have questions we can help you out.