Hello!
Few things I guess. Firstly, your SGS2 should've lasted a lot longer than 8 hours previously. I used to get over a day easily with lots of tweaks, so about a day should be average (unless you're playing a lot of games). What's your usage like?
Next, your battery recharged in 30mins? Was this from 0-ish%? Because it would seem if it only took 30mins that there's a bug in your battery monitor, which is giving incorrect readings. Could also explain to low battery life.
I guess with the manually disabling of Samsung apps, that you're doing that through Settings? If so, that gets undone at a restart. It's probably not the best way to ensure the apps are really closed. I'd suggest rooting and using Titanium Backup to freeze the unwanted apps. All you need to know about rooting and freezing apps is located
here.
I'm stealing ironass' words, but automatic task killers actually drain more battery than they save. I'd suggest disabling that, and also not clearing memory in RAM if you're doing that too.
The ICS upgrade in general has a poorer battery life than GB. This is in part due to a lot of new features designed to enhance the performance of the device. They didn't put as much effort into battery saving unfortunately, which is where rooting and custom ROMs/kernels comes into play.
If you're not into that sort of thing, there's a couple of things that can help save battery:
- Turn off Gmail sync, it's a battery killer
- Download BetterBatteryStats (BBS) from xda
here. Restart your phone, open BBS, and leave your phone idle for an hour or so. Then go back into BBS and use the dropdown boxes to see Partial Wakelocks and Kernel Wakelocks Since Charged. You'll then see what the main culprits are for using battery while the phone is idle. If it doesn't make much sense, take a couple of screenshots and post them up and someone here should be able to interpret them
- Obvious things like disable wifi/bluetooth when not required and use automatic brightness/power saving modes where possible.
Hope that helps!