Sort of an oddity; my tekkeon battery finally bit the dust (age more than usage or damage), so I didn't want to blow a lot of money on another one when I primarily used it for taping and to charge my phone. Looking at the USBPre2's stats, I saw that it doesn't take more than USB power, and even with P48 on and everything, it typically draws less than 500mah with one exception; when it fires up it can draw the full amp. (I think SD told me it's like 450mah, but anyway). So I've been using a cell phone charging battery with mine; 4000mah with 2 USB ports of 2.1a and I think the other is 1a. It's about 1/8th the size of the pre2, and easily 1/5th the size of the tekkeon I was using. The clutch piece is finding a battery that will provide just over 1 amp so you can get it turned on. After that the draw is low enough that I wasn't worried.