3g battery monitor problem

[jor]

My battery is fine but I think there's a problem with the monitor--it always indicates that the battery is fully charged.

I discovered this after using my phone some and having it on standby overnight. The next day, my phone died after an hour or so and I found that the battery was completely drained but that the monitor read fully charged.

Anyone know what I might do? I tried a rest. I even did a restore, and set up my phone from backup. The only thing I haven't done is set up the phone as a new iphone. Should I do this? And will I lost my calendar info and such things?