It is very strange because if it show me three light bars I switch it off and plug the usb in, it will tell me it is charging for about a second then tell me it is fully charged. If I then unplug the usb and turn it off again, then plug the usb in then it will tell me it is charging for some hours, then tell me it is finished charging. I then unplug and I have three dark bars. If after a couple hours I turn off and on, I have two dark, one light, or one dark, two light, or three light.
It behaves the same if I don't turn the device off when it is charging, if I continue to read while plugged into usb.
It must be a faulty battery, I will have to return it.
I hope play.com don't take too long to replace, I will need to do my reading on my pc in the meantime and it hurts my eyes after a while