For those having battery issues after the ICS update: I've got a SG2E4GT and ever since the update, my battery life straight up sucks. Better Battery Stats was telling me that the phone was not going into Deep Dleep Mode. After numerous "fixes" posted here and elsewhere, I turned off Wi-Fi while sleeping, and I am noting a marked improvement.
My battery still drains fast because of where I am, but at least the phone isn't almost dead after three hours of non-use.
Someone mentioned that there is an issue with the phone not going into deep-sleep mode. This seems to be correct, but they were citing the message light as the cause. I tried disabling the light, but it made no difference. Once I turned off Wi-Fi while sleeping, Better Battery Stats tells me that the phone is actually going into deep-sleep. I'm getting pretty close to GB battery life usage now.
I've adjusted my wife's phone and told my father-in-law to make the change on his phone as well. If you do this and it works, let me know in the thread - I'm curious to see if others note a difference.
Please note that my phone is stock and is not rooted, so if you've rooted your phone, YMMV...
I just made the changes you suggested. I hope this helps. The new update is ruining my life! As an Android user, I am used to having horrible battery life but this is just unacceptable
When I upgraded my phone to ICS, my phone battery died within 1-2 hours along with a bunch of other apps locking up and various system services crashing. So I ended up having to reset my phone back to manufacturer settings and got a clean version of ICS out of the box. This finally got my battery up to par like it was before with gingerbread.
Ultimately I ended up buying this extended charge battery from Amazon:
I just came to terms that I use my phone way too much to not do this upgrade, and now I can go almost a full day without charging. Most people claim they can go 2 days or more, but I am a heavy user.
Unfortunately, an extended battery should not be the answer for this issue. This is like taking your car to the dealership for a maintenance check and the dealer telling you that they applied a firmware update to your car that gives you half the mileage you used to get. The only solution is to buy an aftermarket gas tank that doubles your capacity?
I know the analogy isn't perfect, but you get what I'm saying...
At any rate, as an update for the fix I posted above, my father-in-law is now pulling two days of light use on his phone where is was usually dead after less than half of a day.