Resolved Question: how to charge my coby mp3?

just got a coby mp3-705 4g. love it, but seems the battery drains quickly. just got it today and charged it with the computer till it said it was full, but the charge went down fast. can i charge it with the computer while the mp3 is turned on, should i never do that, can i accidentally create a false memory in it so it will only think it needs so much of a charge when it really needs a full charge? please help,