20 - 30 minutos
About 6 months ago, my iPhone would die suddenly anywhere below 50%. Initially I thought it was an issue with the update to iOS 5, but things starting getting worse - to the point where I had to keep it plugged in to be used. On battery, it would almost always die suddenly, even at 100%.
The repair process was a little daunting. Everything is so small and you get a little nervous about losing a screw or permanently damaging something inside the phone. All in all, though, it went perfectly. Phone's working great now - it's like brand new.
Although I didn't do it, a lot of people suggested heating up the back with a hair dryer to loosen up the battery. That was a real pain to get out and I probably should've just done that rather than trying to keep going around the edges trying to pry it out.