I've never posted anything about electronics, or how to fix them, but this was too important to share.
My iPhone battery was dying 4x faster than usual starting over the weekend. My mind immediately went to "it's dead, 2.5 years later and it's dying." I always think the worst first.
I mentioned it to a few co-workers and one actually knew problem and the solution. To Stephen's credit, he did know the problem, but I didn't think it was possible to fix it.
On the iPhone, once you open an App it stays open. (I should note, this is all based on my 3GS and it also works for the iPhone 4.) This drains your battery. I don't read everything about my phone, but when I downloaded the new operating system a few months ago, I didn't hear about this. You can see what apps are open by double tapping the home button. You'll be able so scroll through your open apps. Every app on my phone was active.
To turn off the apps, touch one of the app icons until it starts shaking. Once it's shaking a little red circle with a white line will show up. (Looks similar to how you delete an app from your phone) To close the app, touch the red circle. The app is now closed and it doesn't drain your battery.
It's been 2 days since I've tried this solution to my battery problem and it was the perfect fix. I didn't even plug my phone in last night and I still have more than half of my battery life. Over the weekend the battery was drained in just a few hours.
I also tried this on my iPad 2 and it works the same. Great tip to prolonging battery life!