stock ROM users.
I was actually really depressed by the ICS battery life (i upgraded from GB same day i bought brand new S2), battery life was terrible,
turning on/off syncing, mobile data, gps etc etc helped a bit, but not that much. i still couldent get full day out of it with moderate use.
Again, im on stock 4.0.3 atm.
And then, a miracle.
Let me say right away, i am aware that these types of batterys (i have stock one btw) dont react on this whole "fully discharge then recharge" thing, but i do think now Android ICS as a system does! Cuz it was exactly what i did-i said what the heck doesent hurt to try and i was playing games like crazy when battery was on 10 or less percent so it wld shut down. then, i connected charger and used as normal on charger until it was fully juiced. repeated 3-4 times and what do you know... i now get 50% OR MORE WITH THE SAME BATTERY!
I am not really sure what happend there. Did battery gauge reset? Did ICS "learned" my battery properly? I dont know. All i know is that i am now able to get trough whole day (i get up 7:00AM, go to sleep round 01:00) with only 1 full charge. I dont even bother turning off wifi sometimes when i go out and dont need it.
I have been also reading around the web that some people got the same result. No calibration trys,pulling battery etc etc...just let it go trough few cycles and let system/phone "calibrate by itself".
Not exactly sure if this is a solution, bug, feature or whatever. I just thought it was worth writing to you guys