During that week I was using OReader only but I am not sure if that made a difference. I also had older firmware (1.6.5) and the current one I do have (1.6.6) seems to be less battery friendly. Yesterday after charging over night I left it on screen locked (sleep?) for 12h - went down to 90%. Then I spent reading (OReader, 250 pages with breaks, light 3 bars level) 6 hours. The battery went down to 80%. I turned off and after another 8h it is 75% now.
I must admit I get inconsistent usage after every charge and I can't really say what exactly it is related to. WiFi definitely is a battery hog. I saw here and there that after rooting and removing phone apk the battery is much better but I have not tried that so far. Also... with such a new device in my hands it's not easy to stick to the testing regime
. I'd like to try this and that, read when I want.