Power supply for usb host shield

Hello.What is the appropriate power supply for arduino duemilanove+usb host shield 2.0+Android cell phone+Leds.I use 9volt and 850 mA and the application stop after 1 minute.Any idea?Help?Thanks.

I read this http://arduino.cc/en/Main/ArduinoBoardADK and test it with 2 batteries Lithium 3.7 volt and work well because draws current as needed.I think need power supply 9V 2A.