> I take the battery out after a full charge and use it when I need to. i.e flights

I don't know if this is true for the Internet Tablet, because I only have one battery for it, but I have two for my digital camera, and if I charge them both and have one in camera and one in plastic case, the one in the camera keeps a charge a whole lot longer than the one in the plastic case. This is true even when you switch batteries (i.e. it is not a case of a better and a worse battery, it is a function of being in-camera vs. in-case).