20 - 30 Minuten
I was having power issues with my iPhone 3Gs. Even after a full charge the battery life would be depleted and the phone would power off in a matter of 10 minutes or so.
The repair wasnt that difficult, but removing the screen with the suction cup was more difficult than it appeared in the video.
If you have any repair issues with your iPhone, I suggest you contact iFixit. They are truly a life saver and will show you exactly what needs to be done. Thanks iFixit you saved me from an unwanted purchase of a new phone.
iPhone 3GS Replacement Battery
Phillips #00 Screwdriver