Why does my LG L90 battery goes down from 100% to like 80-75% so fast (about 30 mins) and then the battery lasts quite a while? Is it because the battery has been charged only a few times? Because I bought the phone week ago.
From the question comments, you have not calibrated your battery (in a long time or ever).
You need to do a proper calibration:
- Do a full charge of the device's battery.
- Use the device until it turns off on its own. Do a full discharge of the battery. One neat trick is to get some game that has wakelock (does not let the screen turns off) and leave it running with the device on a well-ventilated place.
- After the device dies of low battery, wait for it to cool down and turn it on and use it a bit more. When it refuses to turn on at all, its fully discharged.
- Plug it in and let it charge to max.
This will set the flags for FULL and EMPTY battery, and the meters should be accurate.
If the problem persists, your battery may be damaged. If the device's battery is still under warranty, take it to the service center.
Do you disconnect the charger immediately when the phone reaches 100%? If so Try an overnight charge and see if this behavior persists.
often times a fast charger may well reach a 4.2 volt peak in your battery but not complete the saturation charge phase before announcing 100% charge. in truth however if the saturation phase is not completed the battery is only charged to about 80% which would be bang on what you are seeing.
My L7 II does exactly the same if not charged overnight (or at least a few hours after the green light.
Do this before doing a possibly unnecessary full discharge witch is generally not very healthy for a lipo cell.
If you don't solve your problem thus, go ahead and do the calibration cycle as described by mindwin.