Sorry if you saw this in my other thread, thought i'd give it it's own one, as no response.

When playing with Background tasks (settings) I have tested the phone with all of my usual background apps "allowed" and then various essential ones "allowed" and then none: all "blocked". The data is as follows:

All within a timespan of 7.5 hours idle (while asleep - no touching the phone). From 12:30am - 8:00am (I'm a student...)
FYI: Bluetooth OFF, Tap to Send OFF, GPS ON, Kids Corner OFF, Location ON, Battery Saver OFF.

With all apps running (Battery Level for WP8, Track My Life, Geo Tasker, My Stocks Portfolio, Nokia Drive+ Beta, Timer, Weather, Photostream)
from 72% to 44% (-28%)

With just essentials running (Battery Level for WP8, Track My Life, Timer, Photostream) (Guessed these a bit, i didn't make a proper note of which ones were running!)
from 78% to 56% (-22%)

With no apps at all running in the background but the system ones (email, alarms, find my phone)
from 69% to 59% (-10%)

I am going to be doing more testing with each app individually turned on to find the culprit, hoping it's not one of the essential ones i want to keep on! anyway - you can see a huge, huge difference - anyone got any info on the power usage of these apps whilst in the background??

By the way, don't know if this had been mentioned before - my battery dropped from 78% to dead overnight a week or so ago - turns out if you have the camera on and just LOCK the phone, it doesn't close the camera, the phone is still processing the "camera" app if not showing it on the screen - same applies to whatsapp - locking the phone while on whatsapp and leaving it DRAINS the battery so fast. Might explain some people's drops - make sure you hit the home button before you lock the phone.

Easy-Snap Photography Tutorials