Originally Posted by Chri5peed
I knew most of that being an electrician, but certainly very handy. Proper care for my Zen Touch battery has meant its kept its capacity for nearly a year, it nearly lasted all the time I was away on vacation last week, well over 20 hours.
Also its important to know that Li-Ion batteries charge at 4.2Volts per cell and USB2 ports run at 5Volts. So in fact DAPs which charge through the USB port are getting the same level of charge as using the mains.
Also, I didn't know, but USB2 ports stay energised as long as your PC is plugged in, but it doesn't need to be turned on. Li-Ion batteries can't be overcharged so its okay to leave your DAP connected to the USB constantly.
i think they can be over charged, its just that the controller will just stop it from happening.
just keep the thing relatively full and it'll be fine. mp3 players are so low drain they are pretty gentle on their batteries.