My biggest complaint about the batteries of my N800s is that the battery meter will read 100% when I leave the house, but then, after a short time of doing some demanding task (most recently, this happened when using a high-speed GPS unit, and later when watching a video using the built-in speakers), the battery level will drop precipitously and the tablet will start panicking about "low battery". I'm never sure, when the tablet is in this state, whether it will shutdown on me or whether it will keep going. But if I stop doing the demanding task, and let the tablet "rest" for a while with the screen dark, the battery level rebounds and everything is fine...