The Audio Buddy runs on 9v AC not 9v DC, so the initial battery won't work. No battery will work. For portable use, you'd need to get a 12v battery, a power inverter (converts DC to modified sine wave AC), and use the wall-wart plug that came with the Audio Buddy. There used to be companies that made an all-in-one 12v battery plus inverter unit that would make for an easy solution (eg, the Vector Pocket Generator). Don't know if these are still made.