I am not having any battery issues on my GS4. However, I've noticed that when in airplane mode (at night), I have a regular battery hit that I have been unable to pin to a particular app. I have Battery Mix, GSAM battery monitor, WakeLock Detector, etc. but none of them are able to tell me what app or service is causing this regular battery hit. Those apps just give me a general usage %age over time. You can see where I put it in airplane mode shortly before midnight when the battery usage flatlines. Then at 1AM, there's a hit, again shortly after 3AM, and then again shortly before 6AM. How could I track down what is causing this? (I'm mainly curious).