Hi to all,
I described in detail exactly the same problem yesterday in topic 'iPhone 3GS battery died?'
http://discussions.apple.com/thread.jspa?threadID=2103226&tstart=45
To summarize: Had iPhone 3GS for 2,5 weeks, all working 100%. One afternoon came home, started charging at 20% only to found few hours later 'charge icon'.. did this and that, and phone came alive with 100% suddenly. Since then it has been acting weird with battery indicator jumping, phone dying already at 28%, recharging to 100% in 30min, phone dying after 55min use, ...
I returned the phone yest to store but in Spain the warranty by them is only 7 days, so instead had to call to Apple and they'll send courier to pick it.
NATURALLY, I still tried to do restores and play with the phone to see if anything would work. Last night after what seemed heavy battery drain, the battery indicator suddenly jumped from 50% to 98%, and started to act like normal, so after 1h or more use the indicator was at 88% - which was actually super good. Well, a few minutes later phone automatically shut down.
I started to charge again, and noticed in the beginning phone was trying to startas it had enough charge supposedly, only to reset itself in the boot process. This happened a few times but then I went to sleep. This morning I woke with 100% and phone powered on.
The battery life still *****, as it dropped to 30% on my way to office, so after 1h or so use.
Even if this phone would start to work normally, I could never trust it again, so Mr. Courier - PLS GET THIS %#&!%!