I seem to be having battery issues with my iPhone 3g. Sometimes when it is plugged in to either the wall or my laptop the battery icon says it is charging yet I'll get a notification that the battery has been drained down to 20%. Other times when it is plugged in to either the wall or my laptop the battery icon says it is fully charged yet when I unplug it the battery is not fully charged. I power cycle the iPhone every couple of days at the very least. My iPhone is not jailbroken and I am running 3.1.2 and I just did a restore a while back to try to help this problem and I have not seen any improvement. Can a Genius check the battery to see if it is working properly? Is there a cost for them to look at it?