Have the same issue. While reinstalling all apps, using the screen, have the ms band connected and in addition just having connectivity with about bar (for both cellular and wifi), I had draining batteries, even I was attached the power. When I stopped using it and just let it install all things, battery took 2,5 hours to load 20% :-(
It is most likely related to the cellular connection. Because during the last days i didn't enter the SIM Pin and at least it feels like the battery drains slower..
just having a look if i already got the new patch to fix it.
And I was so Happy the first 30 Minutes after the Update, as Cortana has it finally arrived to Switzerland, regardless that it uses the the Germany German and not ooffer content for my country...
by the way, the screenshot of an earlier post, where infos about the phone are shown within the browser - how can i get this? or how is this "tool" called, so I can find it out by myself? thx.