I suggest doing a full restore on the iPhone, I used to have a similar issue with my iPhone 4.
http://support.apple.com/kb/ht4137 <- the article on how to do it.
It's normally just a software issue, a restore will clear it all up. Don't restore from backup though, that will normally cause all the issues to come back
I have done a full restore with iOS 5 and set it up as a new iPhone. But the problem is still here. In fact it has become worse over the past few weeks.
Now it will switch off automatically even at 90% battery. But it is usually switched off only when I am using WiFi / 3G / GPS, e.g. surfing Internet using safari, video call in Skype, using Find my Friends.
When the iPhone is plugged in with power supply, it is normal and will not switch off automatically.
I went to Apple Store to find a Genius to look at it but still no clues - the battery is healthy. Are there any other solutions that I can try?
I have the exact same problem. My phone too switches off automatically when I am multi-tasking. Leave alone using 3G, even when I am playing a game in Airplane mode, listening to music, it switches off automatically. Not sure if it is a problem with battery. Any suggestion or help is greatly appreciated.
On My iPhone 3GS started with iOS 4.3 and 5.0 did not improve even with the 5.0.1. When started, the device shut down at around 43% battery. Every 2 or 3 weeks the problem got worse ... 53%, 65%, 75%, 86%, 96%, 98% and 100% now it can be turned off.
I realized that if I use the internet through the 3G off at around 98%. If you use the internet through wi-fi, off at around 86%. If you use 3D games off even faster. The first shutdown can be restored by resetting the system (home + power). But after the second or third, it asks to connect to an electrical outlet, the battery even when it was full. If you make a small charge, enough to start the system will turn off at the next mark (percentages cited above). I started using the iPhone always connected to an electrical outlet (house or car).
Recently I made a painful test: I turned off the 3G, wifi and data transmission; stopped to use all the features of the iPhone, except for calls and SMS. The GPS was on, but I did not use any application that needed it. As a result, the battery lasted about 4 days and declined up to 6% (when it fell during a call). I was very glad to review the battery alerts (20% and 10%) after so many months. Then I waited 1 or 2 hours and recharged the phone to 100%. I noticed that charging was much slower than what was occurring before (and remains so since then). But until now I did not notice a difference in the problem.
Other users with the same problem say revert to factory settings did not fix the problem. There are no Apple Stores in my country, only representatives and mobile phone carriers, but the assurance of my iPhone expired in May 2011, in addition, here we have the iPhone 4S world's most expensive (between US$ 1419 and US $ 1,855), the which means buying another iPhone is a last option. Buy another battery would be easier, but I question: if the problem is the battery, why work properly when does not was required 3G, Internet, games or gps?
It would be nice if Apple responded something like "we are aware of the problem and are working on it." At least we could hope to keep until the next update.
Here are some of the topics of people with the (same / similar) problems:
Mophie Juice idea sounds interesting, but if the error is not mine, I would not have to pay for it, even by a palliative. In addition, the cover that I have gives better protection against shock, but I think it would not be compatible with this extra battery.
switch off at 100% battery now became more frequent. Is very difficult to recover. Once I could get it back by restarting the system 10 times. By the fifth he even ventured, but, in seeking the carrier, hung up. More like 5 attempts and returned it with half the battery.
In another situation, more unfortunate, the iPhone is turned off in the middle of an emergency call. In desperation, I wanted to throw it down with full force. Restrain me, but I do not know until when.