I have this issue that my 3G mobile signal drunk a ll the juice of my battery.
I tried every rom including the latest Android L preview. With every rom I could only survive only 3 hrs of screen time. If I leave it completely not using. The standby time is still within 8 hrs. I used the fastboot to reflash the factory image and replaced the radio version but it didn't help. A brand new battery was also replaced.
I believe it is the modem problem because if I turn on the airplane mode, the battery works great even with wifi on.