iPhone 3Gs battery problems. Dies at 50%

1. Reset phone - press both home and sleep/wake buttons until the Apple logo appears.

2. The battery meter may be out of calibration. To recalibrate, charge the phone fully with the AC adaptor, and let it run until the phone shuts down, and recharge fully. You may have to repeat this 2 or 3 times.

3. Restore phone in iTunes using a backup/

4. Restore as a new iPhone, without using a backup.

If nothing helps, the battery may be dying or there is a problem with the charging circuit. Make an appt with an Apple Store Genius Bar.

I've been having the same problem (3gs - 75% battery signal but dies without warning). I took it to the Apple Store just now and they said to do a Restore 'As A new phone'. I had tried the battery cycling & restoring to a back up. The girl at the store said it needs to be restored completely fresh & the diagnostic showed the battery was fine - make sure you save everything off the phone because it will be like new.

I'm having this same issue for a week now and it is PAINFUL...
I'll try the restore tonight and let you know...

This is a huge issue for me. Not to sound like a TOTAL IDIOT but if I "restore as a new iphone" can I then go back and sync my phone up to get all of my old stuff back on there or do I need to start over blank?

I will tell/warn you...mine started with the battery and has developed into new things. Today it deleted my contacts (after a shut down) and then they came back- all except my most used numbers. So, something funky is going on in there.

My phone has not been the same in a while.

My iPhone 3GS is about 18 months old... and having the same issues for the last couple months. Mine will die anywhere from 35% to 80%. Try to power on, and it will wind up... then shut off when it asks for my passcode.

I went to the Apple store a week ago, and they said to do a restore. Did that... spent an hour putting my contacts back in (my fault, not Apple's)... and the phone died at 68%.

The suggestion is to let the phone run down and die... but yet, if it doesn't run down to zero, but 68%, then does it really work?

Glad to see I'm not the only one dealing with this issue - and glad I can keep the thing charged at work, home and car. Otherwise I'd be stuck quickly.