The Denim update has made my 930 battery life terrible. It's funny. I could not be happier with this phone. After the update my phone gets very hot to the touch and the battery lasts about 2 hours while the phone just sits there.
I've seen some posts about removing Cortana from the start screen.
Maybe I should do a reset?
This is my second time with the 930. The first time battery life was TERRIBLE. This was before Denim. I just got my 930 yesterday! I couldn't be happier. It went from 8PM yesterday until today 12PM from 48% until 10%. Then I unplugged it at around 2, and now it's nearing midnight and I'm sitting pretty at 63%. I have to say, I'm pleasantly satisfied with the battery. Of course, I'm going to need to charge it up and down a few times to fully wake up the battery! But if things stay as they are now, I'll get MORE than a day of use! Yay! And I'm still in the honeymoon phase, always playing with it.
Anyways, what I did was update EVERYTHING right out of the box, and then did a hard reset. The whole, unplug, volume down and power on thing... And then the volume + power combo that you can easily find on the internet, and I reset it completely. Ran through setup again, and that's how I've been using it today. But to be honest, the first 10-15% drops REALLY quickly, and then it sticks to a very constant drop throughout the rest of the day.... I'd give a reset a chance...