20 - 30 minutos
After one of my iPhone 3GS updates last year (the Siri update), my battery started to run down way faster than normal. After a few times of it shutting off on me even though it was still partially charged, I tried letting it run all the way down. It never did.
After being fed up with it cutting off mid call and cutting off when I'm running my accuweather radar, netflix and bejeweled 2 apps - I was this close to swinging it at a wall and getting a new one. Before I did that, I checked the apple support website to see if anyone else was having this problem, and lo and behold, there were more than just a few! (BTW if there is a class action suit on this, please let me know).
The repair went well - I followed the directions of the guide and disconnected everything. When I was putting it back together, the camera connection came off, and I didn't realize till couple days later when I tried using the camera. Took an hour the first time, but only 20-30 mins the second (I was taking my time). I'm still putting the battery through its paces, but I am now able to watch 3 to 4 shows before I have to charge it instead of just 1 and a 1/2.
I thought I had one of those things to pull the screen off around the house, but the only one I had was the one for the GPS, nothing a quick run to the $ store couldnt fix. (This suction cup should be included as part of the buy though - $1.09 for 12 of them...)
Follow the pics and everythng will go well. (Take your time, do it right, you can do it baby...)