Mine seems to be lasting shorter and shorter amounts of time between charges. I've had it for about 15 months, and at first it would last several weeks between charges, with moderate amounts of reading time. Now it seems to barely last a week, even if I've hardly used it. I keep Wifi switched on as I like it synced to my phone, but I have tried switching it off and it didn't seem to make much difference. It feels as though every time I pick it up the battery has gone again now. Has anyone else had this problem?