5 - 30 minuten
My friend had this iphone 4 for 3.5 years and the original battery had really worn out, but getting a new iphone just coz the batery ran out didn't make any sense. So we started hunting for a battery that is of the same quality as the one that comes from Apple. From Apple Store it costs about $86 including taxes for a battery replacement and that didn't make sense. Initially I ordered a cheap battery from Amazon for $7. One for my 4S and another for my friend's iphone 4. While trying to connect the amazon battery to my 4S, the connector plate came off. That taught me a lesson - go for a replacement battery from someone renowned such as ifixit and avoid cheap Amazon sellers' batteries. You don't want an exploding phone by going for a cheap battery.
I had watched the Youtube video from ifixit on iphone 4 battery replacement and the repair took hardly 8 minutes. Ground yourself to get rid of static electricity from your body. The tools given by ifixit were excellent for the job. 1) Open the screws 2) Slide the backplate and remove the case 3) Remove the battery screw and pry the connector carefully out with the plastic pry tool 4) Use spudger and pry up the battery 5) Connect the new battery and repeat the steps in reverse and Voila. It's that simple. Watch the video. That's all there is to it.
1) I am giving this review after using the new battery for 4 months because the repair alone won't do it for me. I was skeptical if the battery would perform like the Apple originals. Guess what? Yes they do. I replaced the battery during 2014 Thanksgiving and now it's midway through March '15 and the battery performs really awesome. Gives a whole day with moderate to slightly heavy usage. Just go for it.
2) Be careful about the grounding plate. Ensure this does not slide off from where you screw the connector back up
3) Put your phone to flight mode and back if the phone has difficulty finding a network once it starts back.