I have an iPhone 3G that's almost 3 years old. I think the battery needs to be replaced, but I want to find out for sure. I do have automatic email checking enabled on it and it's on wifi a lot, so I know that can drain the battery quicker. I'm wondering if there is some way (an app or something) that will test the battery and tell you how much capacity it actually has. For example, I know for a fact that the battery in my laptop is done, I run Ubuntu on it and everytime I boot it warns me that my battery only has max capacity of 30%. I'm wondering if there is some way I can find that out on the iPhone?