Help Battery life dropped dramatically after 4.0.3?


I recently updated my unlocked S2 to 4.0.3 and my phone battery has completely gone!

I always clear apps / RAM in the task manager before locking my phone, but my battery seems to be falling so fast!

At first I thought it was because 4.0.3 reset my screen brightness quite high.

I've put it on automatic brightness like I had before and my screen uses 31% in battery manager and android OS uses 31% too!

I've even seen them go up to about 50%!

Why is it so high??

Also charging takes forever now..!

My battery was on 30% when I started charging it at 9 o clock, it's now 11:30 and it's only on 75% ??


Well-Known Member
Over time, your phone calibrates the battery to get sn accurate idea of how much charge is left. It stores calibration information in a file. When you upgraded this file disappeared, so the phone has no real idea of how much charge is left. Leave it a while and it will get much more accurate.


Thread starter
Well I went from full charge to 0 in six hours today.

I didn't even use the phone much.. it was on lock most of the time, yet display still used around 49% of battery?

I'm going to leave it charging from completely drained, and do the same thing tomorrow after the battery runs down..


Well-Known Member
There is one thing you could try. It was recommended on this forum when I first got my old HTC Desire.

1) Charge your battery to 100%.
2) Unplug it, switch the phone off.
3) Plug it back in, wait for it to charge to 100% again.
4) Unplug it, switch the phone back on.
5) Plug it back in, and again wait for it to reach 100% charge.

By the time I tried this, my phone had calibrated the battery fairly well but I felt that doing the above got it as accurate as it could be, and the battery seemed to last a few hours longer.

I would think that if it works for the Desire, it would work for the SGS2 since, unless Samsung have decided to be clever, battery calibration will be handled at the Android system level. And a LiION battery is a LiION battery...


Android Expert
When I first upgraded to ICS I found battery drain pretty bad, then suddenly overnight two days ago it's settled.
Now I get as good life if not better than I had with GB.
Give it time, it takes a week or two to bed in.

Oh and stop killing your tasks, let Android handle it.
When you kill tasks that Android needs it's forced to restart them again and a lot of the power needed by an app is during app boot time where it generally uses much more CPU to get up and running as quick as possible.
By killing apps you are killing battery life.
Android will shut down those apps when it needs to.

The only time to use the app killer is when something has loaded you aren't going to need again (i.e accidently launching bloatware) or an app goes mental and crashes.