"Battery Pro rocks!" - @Tramain360
The most accurate Battery app for your iPhone or iPod Touch.
The Battery app monitors what your battery level is over a period of time and calculates the time remaining to empty or to full.
It also monitors what processes are using up your battery and shows which processes are the most likely suspects.
It is an ESTIMATION of previous behavior and if you use your device differently, the calculated remaining time will be different.
Using the Battery app frequently increases the accuracy of the time remaining calculations.
The Battery app comes with some default settings to calculate the time to full charge or to empty.
For best results, use the Battery app often while charging and when not charging.
The more often you launch the Battery app, the more accurate the time remaining is. The calculations are affected by how often and how intensively you are using your device.
The time remaining is based on your current usage since the last charge cycle. If you haven't used your device and the Battery app much since the last charge, the time remaining will be calculated using the previous discharge cycle.
From the same people who brought you System Activity Monitor.