I have the 800 and the iPhone 4S before that and both phones had the fast draining battery at first until I found something that seems to drain a lot of battery with out you knowing.
Turn off all FEEDBACK!!!! There are a few places in settings where feedback is enabled by default and if it's on, it's constantly monitoring youre system and sending how you use you're phone data to Microsoft.
The main one is settings - feedback
There is also settings - keyboard- typing settings
Also in Internet explorer sending search data is on, turn off
And anywhere else you can find feedback it's not needed and won't change how the phone works (except give better battery life lol)
Try it I found it doubled my lumia 800 and my iPhone before that.
Turn off all FEEDBACK!!!! There are a few places in settings where feedback is enabled by default and if it's on, it's constantly monitoring youre system and sending how you use you're phone data to Microsoft.
The main one is settings - feedback
There is also settings - keyboard- typing settings
Also in Internet explorer sending search data is on, turn off
And anywhere else you can find feedback it's not needed and won't change how the phone works (except give better battery life lol)
Try it I found it doubled my lumia 800 and my iPhone before that.