sorry late respohdihg - it does charge off the usb, or you can charge it faster with the charger that comes with it. the bat is supposed to last 52hr / chg when new. mine is the 8gb model which i use with 16 and 32gb sd flash cards. i use it w/grado sr-80s and it sounds pretty good. I have had to reinstall the firmware a couple of times so back up your files. I got a squeezebox touch so I'm not using the cowon as much these days. oh - i also got one of those fiio e3 AAA bat line level booster (amp) to use when plugging into car stereo to give extra output - sounds pretty good with that too
