10 - 30 minuten
My iPhone 4S was having several issues. One issue was the fact that anytime the battery would get down in the low 30 to 20%, it would sometimes just shut off. It would show the "needs charging sign". If I plugged it in, it would turn right back on showing that it still had a charge. If I just waited for 10 minutes without plugging it in, it would turn back on showing the battery still had the charge. It was also having issues being very slow at times when trying to access the internet, not receiving calls, and having poor reception.
Installing the battery was pretty easy, anyone can do it. Get the tools with the battery! After installing the battery, the phone turned on and was stuck searching. I simply restarted the phone and it connected right up. The battery came with a 70% charge. I charged it up, used it until it ran out and recharged to 100%. Every issue my phone had is fixed!
Just be mindful that these screws are the smallest screws you may ever have to deal with. Make sure you have good lighting and a possibly magnifying glass. I got mine with the tools, I couldn't have done it without them!