Have you got to that point of not liking how long your iPhone battery charge lasts? Or were you like me and tried to always use the phone while it's attached? (so much for a "mobile" phone) I have researched 3 options for replacing your iPhone Battery.
Option 1) Apple
Have Apple Replace the Original iPhone Battery
If you want Apple to replace the battery for you it will cost $79, plus $6.95 for shipping. During this process your iPhone will be completely erased! The time it would take is about a week from the day the iPhone is shipped to Apple.
Option 2) DIY
Replace the Original iPhone Battery by yourself.
If you want to replace the battery yourself, you will need to find and purchase the correct battery for around $19.99 (You cannot just buy the part from Apple - be cautious on where you buy it!). After you have purchased the iPhone Battery, here are the steps it will take to replace the battery.
[Warning!] Replacing the battery yourself voids your Apple warranty for your iPhone product. Only attempt such an activity if you are certain you can execute the task correctly and are certain you are either out of warranty or will not need to utilize your warranty.
Tools: You will also need to have some tools such as small Phillips Screwdriver and a Spudger (A wiring tool used for poking or adjusting small wires or components.)
1. Locate small hole next to headphone jack. Push the tip of a needle or paperclip into hole to eject sim tray.
2. Hold your device on end to locate two small screws on either side of the dock. Remove the screws using a small Phillips screwdriver.
Insert a spudger between the chrome ring and front panel glass directly above one of the screw holes. Pry gently to separate the display from the back panel.
4. Lift the panel up from the dock end being careful not to tear or break any ribbons connected near the other end.
5. Continue to hold the display panel with one hand, and use your other hand and a spudger to disconnect the black ribbon cable labeled "1.
6. Rotate the display assembly up until it is roughly vertical. This will allow easier access for disconnecting the remaining cables.
7. Use a spudger to disconnect the black ribbon cable labeled "2."
8. Use a spudger to flip up the white plastic tab holding the remaining ribbon cable in place. The white tab will rotate up 90 degrees, releasing the ribbon cable.
9. Slide the black ribbon cable out of its connector, and remove the display assembly from the iPhone.
10. Remove the 8 screws surrounding the motherboard:
Five 2.3 mm Phillips screws with partial threads securing the logic board to the rear panel.
Two 2.3 mm Phillips screws with full threads securing the logic board and camera.
One 2.9 mm Phillips screw from beneath the "Do not remove" sticker.
11. Unplug ribbon 4.
12. Lift the mother board out. Be careful not to rip the ribbon connecting the camera to the underside of the board.
13. Unplug this connecting ribbon and place the mother board aside.
14. Use a spudger to gently pry the camera up and out of its housing in the rear panel. The camera cannot be removed entirely yet because its connected to the bottom of the logic board.
15. Use a spudger to gently pry up the end of the logic board closest to the dock connector. If the board won't lift up, double check to make sure all the screws securing the logic board have been removed.
16. Slide the logic board towards the dock connector and out of the iPhone.
17. Using some force, pull up on the attached tab on the battery to remove.
18. Replace battery
19. To reassemble your iPhone, repeat the previous steps in reverse (another 17 steps).
Option 3) Backup iPhone Battery
Purchase an External Battery or Backup Battery
If you want to make your iPhone last longer and want a solution that's less intrusive, check out these alternatives. You can get an External Backup Battery that extends your usage time up to 2x and charge your iPhone at the same time (Works with iPods too!). If you have an iPhone 4, consider a Rechargable Battery Case. It is a protective exoskeleton for the iPhone 4, outfitted with a rechargeable external battery to give the iPhone extra battery life.