Below is a log of when I started to notice this issue and when it happened. today did a restore to new and we will see
Shut off at garage dec 5 round 5? Had like 13-15% and then shut down
like the battery was dead. Tried to turn on but it gave me the charge
it symbols so I left it for a few minutes and then tried to power it
and it came on. Showed 9 or 10% checked the Internet got down to 7
and shut off again same thing. Turned on had 5% texted a few times and
same thing. Left it got home and charged it from the wall.
Phone is doing the same thing around 15% battery a couple of times to
3% I plug into computer and charge while doing a restore. Hope this
Restore seems to have worked. We'll see
Phone shutdown would not turn back on had 6%. Got cable and plugged
into wall and phone powers right up on its own soon as I plugged the
cable in the apple appeared on the screen. And showed 6%. Charging it
now. Plugged into wall fack!!
Phone acted same way as 15 of dec. not happy camper. Lol
Showed 11% started trade nations and after a min phone shutdown.
Plugged in and after restart 5%.
Maybe there's a bug calculating the battery's remaining charge?
Jan 2 2013
Phone shutdown and when I plugged it in it started up and showed 12%
Jan 6 2013
At the park phone had 36% took a few pics of the kids put phone away
for a min took back out and shutoff saying charge. Left in car for 15
min not charging and turned phone on and it has 33% life ***!!!!!
Shopping at store and phone shuts off at 23%. Tells me to charge. Wait
for a few mins and power back on. 20% send text and phone shuts off
again. Bring home and plug into wall as soon as its in phone starts to
boot up and shows 16% battery life. Call apple and advised to restore
and setup as new phone and see how it is.
Jan 20 phone at 8% plugged in and phone displayed 31%. 5 mins later
the phone says 25%. Unplug and answer a couple of texts 18%. Weird.
Plugged back in.
Jan 25 Actual restore to new and start from scratch. More outa desperation cause I dont have a cc for express repair and the free option taking 2 weeks will be hard as this is my only phone.
Similar experience in cold weather. I think it is normal. I think iPhone 5 actually handles it a bit better. My 4 used to suddenly lose power in the cold and would require charging before it could be powered on, even once temperatures rose.
Today my iPhone 5 had 52% batteries. It was in an inside pocket, but I went higher up a mountain today and the temperature dropped to -15. Even with the phone in an inside pocket, it shut down. I have seen it do this while watching the screen - it does not go down to low battery and then power off, it is a straight shut down. It won't respond in this state even to show the 'charge' screen.
But now in a warm restaurant, after a few minutes warming up, it's powered on and is right back to 52% where it started. Assuming you are below 0°, I think not a fault, just the way the batteries respond to cold. If it happens when it's not that cold, perhaps there is another issue.