I have a Xiaomi Mi A1 phone with newest android oreo.
On first days of use, it almost didn't lose any battery charge over offscreen time , i could leave it on the shelf while running in offscreen for 3 days and its battery still had power..
After i installed some apps, the difference in battery drain is insane.
I leave the phone on the desk for like 3 hours and it loses 40% battery
I have this AccuBattery app to measure battery drain.
For example i left the phone for 18h on the desk in offscreen, didnt use it, and it drained 78%..
Used for 18h 9m
80% to 2%
Screen time : 2m
Deep Sleep : 3min
This AccuBattery has "per app usage", but it shows nothing. It only shows like gmail used 2 mAh, maps used 3mAh, and another used 1mAh over 18h, but its nothing compared to 2207mAh.
I just want to know why does my phone drain battery in screen off mode so fast.
My mother also haves a same phone, she hadnt really used it ,hasnt installed any apps, and her phone can last for days in offscreen without charging..
Would it do anything with apps in backround? (AccuBattery didnt show they use too much battery)
I have these apps, some usually send random notifications:
StopAd, AvastAntivirus, GoogleMaps, GoogleEarth, Skype, "Mechanical Engineering", some games.., voice recorder, wifi analyzer, Picai, 9gag..
Actually, increasing battery life for Android Phone is not such a difficult thing as you think. To make your device run for a longer time, you only need to adjust some settings of your device like reducing the brightness of screen, disabling wireless network, quitting background software and so on.
Here is some tips that could save battery life.
1. Lower Screen Brightness
2. Tighten Up Auto-Lock the shortest period for your device, namely 30 seconds.
3. Turn off Wi-fi if You Don't Need It
4. Limit Background Refresh for Applications
5. Restrict Unimportant Notifications
6. Don't Update Apps Automatically
7. Do not Activate Location Service
8. Use Low Power Mode
Hmm.. Are you always connected to the internet? If so, that maybe the reason behind it. You might also want to try draining the battery and fully charge it while it's full.