LOTS of batteries - figure 3 or 4 (maybe more) 90Ah gel cells. If the repeater draws say, 25 amps, that 360 Ah will get you 1/2 day of continuious use. You'll find however, that after the first couple of hours, the use falls off to about 50% duty cycle. In addition, most repeaters that ARE on battery have foldback setups that will drop their output from around 100 watts to around 50 watts if running on battery - Now your only drawing 10 amps or so, so you can go 36 hours full time, and with duty cycle built in, usually a bit more than 2 days