Just wanted to share my solution if someone has similar issue with battery drain:
I have Onyx Boox Note Pro (Google Play enabled) and recently updated to V3.0 fw. It started extremely drain battery after that. Especially it started being annoyed because I couldn't use sleep mode instead of turn it off (to do not wait each time util Android boots).
The strange thing was that before the update battery life was acceptable (without using Wifi) it lasted weeks for just reading and note taking.
I started investigating what may went wrong and used battery profiler:
https://developer.android.com/topic/...tery-historian
It didn't help much, except I found that something alone took 84% of battery. I went to adb shell and executed "top" which gave me:
PID PR CPU% S #THR VSS RSS PCY UID Name
4052 3 26% S 38 1305136K 143800K bg u0_a6 com.google.android.gms
237 1 8% S 9 66704K 11064K fg media /system/bin/mediaserver
189 2 1% S 6 23440K 16532K bg logd /system/bin/logd
5676 2 0% R 1 2188K 952K fg shell top
It means that Google Play Services take fully 1 core of CPU for all the time. OMG!
That explained everything.
I just went to Settings and found that Location was ON and Google Services have access to Calls/SMS, etc.
So my solution was:
0 - Go to Settings -> Applications -> Application Info
1 - Disable Location service (Google Play Services -> Location (tap) -> Location Settings -> toggle it OFF and disable listed location services: ELS, etc
2 - Remove all permissions from Google Play Services and Google Play except "Storage" and I also disabled Google Play (just in case)
3 - Force stop Google Play Service app and Google Play
I also have Airplane mode enabled and "Power Save Mode" on. When I need Web browsing I just tap on Wifi icon to enable Internet access just for time I'm browsing.
I would be glad if this experience helps someone else. I didn't check thoroughly all forums here, maybe it's already explained somewhere (sorry if this is the case).