I'm wondering about the battery life of my 8GB iPhone (second one, first had a dead pixel, so I exchanged it). It says, under Usage, that it's gotten 4h39m of usage and 2d12h of standby. The last battery warning I got was 10%. Is that normal (good) battery life? Edit: By the way, I have been leaving it on standby/sleep at night. Should I be turning it off? Does the on/off change waste battery power, or is it worth it?