Experts, need some advice and information regarding the stock battery in my Thunderbolt. Lately I have been suffering from random shutdowns, not reboots. It ONLY occurs when I am on the internet, unplugged, using 3G or 4G. If I am plugged in or on WiFi, I can surf all day. Oh, it I am using an app such as facebook or other internet reliant app, it will behave the same. I could be at 90%, but when I turn phone back on, it will show battery down to 20% or less. BUT when I plug it in to recharge, it jumps back up to around 70% or more.

I installed an app today to monitor battery, thinking thats the problem. I charge at 4212mV, but when unplug, I am dropping to around 3730 - 3900mV while keeping screen on and music playing. In 8 minutes, Ive dropped to 89%.

Here is my usual behavior with the phone. Plugged in from around 10:30pm till 4:30. unpluged for almost an hour, then plugged back into car charger for drive (aprx 45 minutes), then used on bus for around 1 - 1 1/2 hour mostly music, some facebook, a little surfing. then a short walk and plugged into dock for listening to music at my desk. reverse that on the way home. Usually unplugged from 5:45pm till 10:30pm.

When at home, usually WiFi, 3g to 4g elsewhere.

So, is this battery or something else? I just want to find the issue before heading to verizon since I am rooted.

Any advice or suggestions are welcome!

Thanks in advance!