iPhone free Apps– Utilities that worth to install

Battery Life

beside showing the percentage of battery life left, it also indicate the balance usage time of

Standby, talk on 2G, Talk on 3G, Internet, Wi-Fi, Video, Game Play 2D, Game Play 3D, Camera and Audio

Battery Life Checker,  to maximize the spend of battery life.
This apps will also show you when is the best time to charge.