BACKGROUND I bought my Bionic on launch day along with the extended battery. I've greatly enjoyed the phone, but my battery life is mostly horrible. Specifically, there are many instances of unexplained battery drain even when my phone is idle in my pocket. I don't expect miracles when the screen is on or when I'm using data, but I'm rarely getting more than 8-10 hours of EXTENDED battery life. So I set out to try to discover what's going on... TEST CASE Battery Profile: Maximum Battery Saver with data off in 15 minutes Wifi OFF 4G ON Bluetooth ON So my typical usage involves charging my phone to 100% before I leave for work. I am able to listen to Bluetooth headphones at work, so I normally have the phone in my pocket and listen to local podcasts (no cell data) via Doggcatcher for about 4-5 hours of my 8-hour shift. I have two 20-minute breaks where I use the Mobile Hotspot with my Macbook Air. The screen is on no more than 10% of the entire shift. During the first 3 hours, my battery dropped very little. When I went to break and checked the stats, I was still at 90%. Then I turned on Mobile Hotspot and used it with my Macbook for about 20 minutes. When I went back to work, I turned the Hotspot off and I was at 80%. Yes, I realize the Hotspot uses a lot of juice and it was probably closer to 80 than 90 when I first got to break anyway. Here's where it gets interesting. During those first 3 hours before break, the battery graph shows that the phone was sleeping most of the time, even while I was listening to podcasts via Bluetooth. Obviously it shows the phone waking up when I turned on the Hotspot. However, when I went back to work, I used the phone EXACTLY like I had the 3 hours prior: screen off while listening to podcasts. Only this time, the phone NEVER went back to sleep the rest of my shift (even when I stopped playing podcasts for a while). And the battery dropped a LOT faster after my first break as well, even though I was doing the exact same thing. So I'm convinced that there is perhaps a software bug of some kind that is preventing the phone from sleeping under certain conditions. I have tried to use the process of elimination to discover the cause, but I am at a loss. I was at 15% battery life when I left work after my 8-hour shift. Here are some of the reasons for large battery drain: 1) POOR SIGNAL. In areas where the phone is getting poor signal strength, the phone has to work harder to stay connected to the cell towers. Thus, battery life will not be as good when signal strength is poor. In my location at work, I'm in pretty much the same spot and get 1-2 bars. So signal strength is not good. HOWEVER, during the first 3 hours at work, the battery dropped very little, whereas during the remaining 5 hours, it dropped very fast. During the first 3 hours, it went from 100 to 90. During the remaining 5 hours, it went from 90 to 15. CONCLUSION: Though battery life may be less when signal strength is poor, this is not the reason my battery level drops quickly at certain times during my shift. 2) BLUETOOTH DRAIN. I know quite a few have reported that Bluetooth uses a lot of battery. And since I'm connected to my headphones the entire time (though only playing for about 4-5 hours), one might think that Bluetooth is the cause. However, again, I was listening to my headphones those first 3 hours and the battery only went down 10%. Furthermore, the phone was actually sleeping during those first 3 hours, whereas it stayed awake the remaining 5. CONCLUSION: Though Bluetooth certainly takes a toll, it should actually be fairly minor. 3) ROGUE APPS/WIDGETS. I only have a couple of widgets on my phone, and they are set to sync once per hour. But I also have the battery profile set to shut off data after 15 minutes, so my e-mail, notifications, and widgets don't show up until after I turned the screen back on. I did not use ANY apps during the shift, aside from Doggcatcher for podcasts and the Mobile Hotspot. So there's no app that would have been running after the first 3 hours to cause the abnormal drop in battery life. HOWEVER, I cannot confirm whether the battery profile settings are actually working. Since the phone is not going to sleep properly after I came back from break, I cannot be certain that the battery manager is actually turning off data. Still, the two widgets I have would not use much battery only being synced once per hour. And there doesn't appear to be any large data usage during this time, so I don't think there were any rogue apps or widgets. 4) MOBILE HOTSPOT GLITCH? Obviously, the battery drained faster during those 20 minutes when I was using it during break. But I made certain to shut it off before going back to work. And I confirmed that the network was not showing up on my Air once I turned it off on the phone. I initially suspected that maybe the Hotspot was not being shut off properly, leading to the phone staying awake anytime after using it. I can't rule it out, but since the network is no longer showing up on my Macbook when I turn it off, it seems to be turning off properly. Still, it does seem suspect that the phone never went back to sleep after using the Mobile Hotspot. *** Has anybody else who's used the Hotspot feature noticed any kind of unusual battery drain after using it and turning it off? 5) SLEEPING. I don't understand what makes the phone decide when to go to sleep or stay awake??? This may be the key to my troubles because it seems like my battery is not dropping much at all when the phone is properly sleeping, but drops a LOT faster when the battery graph shows it is staying awake. Furthermore, I can usually physically feel the phone warmer in my pocket when it's not sleeping, whereas it stays room temperature when it is sleeping. Can anyone explain what determines whether the phone goes to sleep or stays awake? I can confirm that the phone CAN sleep while playing podcasts via Bluetooth, though I'm not sure how that's possible? For the first three hours, the phone slept most of the time and the battery dropped very little. And then later on, I actually turned Bluetooth OFF for about 1/2 hour to see if the phone would sleep and it still did not! So something OTHER than Bluetooth was keeping my phone awake. So I'm really baffled by all of this. When I use the phone other places outside of work, the battery also seems to drop very quickly, though it's very inconsistent and may be related to the same sleeping issue. I can have my phone in my pocket doing nothing - with Bluetooth and Wifi both off - and the phone will still drop about 10% per hour. And this is with the extended battery! When I use the stock battery, it only lasts about 5 hours max. I know some have suggested defective phones, but since there are times when my battery does NOT drop very quickly (usually after a reboot), I'm leaning towards some kind of software issue. Perhaps it's a battery management issue. Perhaps it's an OS issue with sleeping. I dunno. But it's almost enough to make me return the phone even though I love everything else about it.