battery percentage drops suddenly from 10% to 1%

[Thomas Meyssonnier]

The battery percentage drops from 10% to 1% and probably less in about a minute, even with phone locked and inactive.
This has happened twice in a row already, and probably will systematically.
Battery warning means I need to plug in instantly to avoid shutdown.
There seems to be no way to calibrate battery measurements, or set a different warning level.
I have no idea where to get log history for battery level, but I'll do it if someone gives me directions.
Thanks,
TM

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: upower 0.99.2-2
Uname: Linux 3.4.67 armv7l
ApportVersion: 2.17.2-0ubuntu1.3touch1
Architecture: armhf
CurrentDesktop: Unity
Date: Mon Mar 28 01:20:15 2016
InstallationDate: Installed on 2016-02-17 (39 days ago)
InstallationMedia: Ubuntu 15.04 - armhf (20160217-111536)
SourcePackage: upower
UpgradeStatus: No upgrade log present (probably fresh install)

[Thomas Meyssonnier (thomas-meyssonnier)]

Update:
It only seems to happen when phone stays plugged for some time (4h) after end of charge.
 Then it stays for a while at 100%, and drops suddenly from 10%.
Problem disappears if phone is unplugged within 2h after full charge.
So maybe a calibration problem, but possibly without solution due to changing battery parameters (voltage for energy, etc...).

[Thomas Meyssonnier (thomas-meyssonnier)]

It seems to be getting worse after current stable update (Ubuntu 31), battery refused to load beyond 58%, probably because voltage was above charging voltage.
It really seems like power driver is taking relative units for absolute, or making some strange kind of calculation towards charge/discharge level based on measurment statistics.
Right now it resumed charging after switching to another power source, and some persuasion. I have no idea what's going on at low level seeing as the battery indicator looks like it's yielding arbitrary numbers (though it does rise when charging and fall when discharging).
Shouldn't we be giving a relative index, or possibly measuring percentage by comparing this index with minimum and maximum values? Is that already what we're doing?
Anyways, thanks for any help on reading the battery indicator. Seeing as Ubuntu phones ship with non-replaceable batteries, the least would be not to kill them within a month.

Thanks for your work (and I guess it's hard to predict physics),
TM

[Thomas Meyssonnier (thomas-meyssonnier)]

Seems better now (OTA-10.1-20160408.4), percentage behaves correcly between 10 and 5. I don't need to drop everything to find my charger, thanks !
TM

[Thomas Meyssonnier (thomas-meyssonnier)]

At this time (OTA-11-20160524.1), the bug still persists.
Battery stayed fixed at 10% for hours, then dropped suddenly (the unit powered off before I could plug it, which takes less than 5 seconds usually).
I also have instances of the phone consuming its battery overnight, when it should be sleeping. Although maybe this is another issue.

A phone that can't be relied on will be difficult to accept by the public, so could someone please look into this ?

Thanks, TM