I was getting only 5 to 6 hrs of life for a couple of weeks now. I read a few posts where people were experimenting with diabling background data. I tried it myself last night.I also at the same time, changed the network from cdma/lte to just cdma and left the wifi on all the time. I am now at 38% battery life 18.5 hrs later.
My exchange mail seems to still be getting emails right on the mark as well, but my calendar is having trouble updating (this may be unrelated). I have a funky exchange servie (lotus notes traveler), but I'm using Enhanced Email as the client. It has been the only client I have tried so far that understands how to accept meeting invites with my server. Even touchdown does not know how. my understanding is that EE has a known issue with ICS and Calendar updates, so this may be the cause of this issue.
I put CPU Spy on and it still shows that I hardly go into deep sleep even though I got 18.5hrs out of it so far. I now need to figure out what apps are going to malfunction with the background data disabled. I tell ya, I was ready to trade this in for a iphone (I was getting pretty depressed with the battery performance, or lack there of).
18hrs of life on a standard battery is just fine with me, but I still want to know what bad things are around the corner with background data turned off.
Tonight I will try just switching onto the cdma/lte and see the effects. Tomorrow I will kick background data back in.
I probably should try to see why I cant deep sleep before I do any of these additional experiments.
I also have Set CPU set for set to "ondemand" state.