Inconsistent battery drain while idle

[fthis f]

Overnight my phone is idle 7-9 hours. Mostly 8-9 hours. I've noticed the battery drain on my C5 pro with a 2600mah battery ranges from 3 - 9% with the occasional 15% drainage here and there despite the fact that every night I put the same apps to sleep, turn off bluetooth and wifi and I don't use location services.

The top apps are Android System and Kernel Android OS.

The other night I let it run with the mp3 player and I lost something like 14% in 8 hours. Today I went out and used the mp3 and lost the same amount in 5 hours. I did use the camera to take about 5 pics and had the wifi on for 2 mins to connect to my dslr.

It seems to me the battery life is a bit erratic or inconsistent, especially the idle drainage.

 

[Rukbat]

Android System and Android OS is basically the whole phone minus the apps. If an app updates, or the OS updates, it takes battery.

Also, the method of measuring the battery State of Charge isn't that accurate. (To measure it accurately, the battery has to be taken apart, so it's a one-time measurement.) 4-5% of that variation could be just from starting with a different charge (unplugging the charger the moment it hits "100%", and leaving it plugged in for an additional 10 minutes, gives the battery different amounts of charge), so the discharge curve isn't accurate. (The SoC is "measured" by measuring the voltage of the battery [which doesn't vary much from full charge to discharged, so it's difficult to get that last decimal accurate], then comparing the voltage to an internal "voltage vs. State of Charge" curve. If you start with a different amount of charge, the curve is off.)

3% to 9% in 8 hours of idle means at least 2 days of idle (down to 40% charge, at which point you should plug the charger in), which isn't bad.

 

[fthis f]

Thanks for taking the time to explain. I know the discharge curve isn't the most accurate and there are many factors but as a basis for comparison with my old phones, I compare the same usage patterns to try and keep them as similar. I use Gsam and take the averages the same with this phone as I have with my last two. I'm more worried about the inconsistency of the drain from one night to another. All my other phones have been pretty consistent and predictable with that sort of thing. I can't tell if there's something I'm doing to trigger it or not.