My charging/consumption of power has been totally fuzzy until I was told by s-o in Nokia Labs

- to charge over very long period of time and consume 100% (full cycles) 4 to 5 times in a row. nothing new, but I must admit I did not do it in the first place and I used the n800 while charging at first
- to switch OFF Wifi and BT connections when not using the N800 as variations in the field and refreshs create variations in the consumption rate.

Now it s VERY steady. I don't know if this helps.