Can anyone confirm the power supply specs for the alarm base station (for US)? I assume it's a transformer based setup since it has battery backup built in. From what I can find in online images, its a transformer style plug (big block at the wall end of the cord). Can someone get me the volts/amps from their power supply? I am interested in this system for my RV but I don't always have AC and would like to determine if I can build a direct DC power setup for it.