Hey all...same here. I went to work, came out (phone on standby for 8 hours) and my battery went from 85% to 19%...so I called VZW. Here's what we did...
-Pulled the battery, waited 20 seconds, put it back.
-Powered back on and updated the roaming...dial *228 and select option 2
-He told me to monitor it and he'd call me Monday to check on it...or if I was still having problems that I could always call back.
Once done, I charged my phone to 100%, took it off the charger, left Mobile Data ON, I always leave WiFi ON, put it in standby and went to bed. 10 hours later, it is still at 91%! Holy ****, they actually helped me on this one.
Hope this helps...