i was able to run my Eken M003 with a 6 volt DC lead acid battery rated at 4.5amp/hours. Once its running the voltage has to stay about 5.8v or the system powers down. I recommend 7.2volts power for external battery pack, and 9V 1amp will work for just bedside surfing and to keep system from completely draining. Playing Pandora my M003 drained 1.2 Amp from the external battery. I'm guessing the M001 should only need 1 amp, to run and trickle charge. 6v-8.4v for using9v for using and chargingCheck my post, I have more details and I upload some Youtube videos on total power usage on M003, should be similar to M001 (about 100-200 milliamps difference because of screen size)