I haven't noticed a change in battery since upgrading to 8.1. Usually I get around 10 hours of usage but now with 8.1 usage time reports much greater numbers than on 8.0.2. I still have to charge the phone as often and I don't feel that battery life has improved as the usage time points out. Does anybody else experience this? By the way, I really haven't used the phone constantly 50% of the day as the usage time suggests.