after update to IOS4.2.1 my 3Gs battery % keep dropping

I've noticed similar problem recently, not 100% sure if it was after updating to iOS 4.2 but I would go from 100% charged before I sleep to 80% when I wake up 5-6 hrs later.

I've noticed when I look up the usage in settings, the usage time is exactly the same as the standby time, which I can't seem to explain even though I'm not even doing anything with it.

It's got to the point where I have to charge it daily, when before it could've lasted 2-3 days if I didn't use it.

PS. I do not use it for any email/web surfing. It is primarily for the iPod and maybe 5 mins of Angry Birds =\

Message was edited by: Nagisama

Hi guys 🙂
just to tell you that i've recovered from this problem by restoring my 3GS. However, there is another error after my restore. My iPod on my 3GS , the albums are not categorize. If you are restoring your iPhones, after which, please tell me if you have the same problem.

Thanks

I have also noticed a similar degradation in battery life. I have been told that if I go to an Apple Store they can run diagnostics to identify the problem. Have yet to get to a store but I would suggest you do if you can.

The battery drain problem after installing iOS 4.2.1 is "Find My iPhone".
(it keeps running on the background, thus drain the battery even you don't use the machine).

Just do these and the battery problem will be fixed :
1. Turn OFF "Find My iPhone" (setting->email->MobileMe)
2. Install this profile from the iPhone :
http://support.apple.com/kb/TS3398