If I read the picture right, the wall plug said it had an input of 120 V AC and it converted it to 12 V DC which would be the same as a car battery, so all you would have to do is find a 12 volt battery and connect it, or you might have to make a connection depending on of it is a standard connection or not. Even if it does not convert it to 12 V DC, as long as the screen is taking in a DC current, all you would have to do is find a battery that matched the predetermined current.