Correct Panda Battery Procedure:
When the device is in use on Computer, do not use USB charge. Turn it off. When the E17 is on it's final bar of battery, turn USB charge(or the USB cable) on and charge it to full. And then unplug or turn off USB charge and use until you are on your last bar of battery left. When you see the bars reduce to one, it would be best to start charging(sometimes you are out, and you can't, that's understandable, a few times charging from higher up won't hurt). Li-ion batteries like the one's found the in the FiiO E17 Alpen's don't react well to a full cycle of charge and FULLY de charge until the battery is dead. This has been proven to be actually bad to the life of li-ioin batteries. HOWEVER., you should do a full cycle where you fully charge up the device and use it all the way until the device automatically turns off ONCE a month as that has been shown to actually be good for the battery WHETHER you use it constantly or not. Do not fear my friend, even if USB charge is turned off when the device "dies" it will still charge after it runs out of power naturally!