5 - 30 minutes
After about 4 years of owning an iPhone 4, the battery finally started to degrade to the point it would get a couple hours of use before shutting down. Mind you, I treated the device very carefully, never overcharging the battery overnight or other rookie moves that can kill it faster. So it had a good run, and since the device itself is still in excellent condition, why pay top dollar to replace the entire phone?
Quick, easy, and painless. I did not purchase the Magnetic Project Mat. Instead, I put down some clear double-sided tape on a white piece of paper, and that worked well enough. The tiny size of the screws are worth those with poor eyesight to consider purchasing the Mat.
If you are going to replace more than your battery (my power button also stopped working), do it all in one repair, but make sure you have all the parts and tools necessary. Turns out that the battery replacement kit includes all the necessary tools and parts, but the Power and Sensor Cable does not (it is missing a crucial screwdriver). Of course, this is my fault because I didn't read the fine print of the instructions, but it was a little frustrating to find this out after going 60% through the repair instructions, which including removing my camera.