On a few occasions the phone battery has drained flat and consequently the phone has shut off. When I then attach the charger, the status LED comes on solid red but the phone does not power up, the phone is unresponsive to power key input (short or long press).
There is a bit of a dance required to bring it back to life, for which the novelty factor wore off after the third time.
I have since upped the battery percentage threshold at which UPower steps in and takes action to shut the phone down when the battery gets low on charge from 2 to 4%, I also upped the critical threshold from 3 to 6% otherwise there would have been a nonsensical threshold overlap.
Since adjusting the thresholds, I have let the phone battery drain flat and shutdown a few times now and after each time when I attach the charger the phone powers up without any further intervention. It seems, at least for me, that UPower’s 2% threshold is a little optimistic and the battery does not have enough juice to provide power long enough for a clean shutdown. This is with the cellular modem enabled, the wifi card enabled with bluetooth on and operational and wifi disabled in software, I’d consider the 2% threshold even more optimistic if WiFi were enabled and operational too.
UPower’s config file can be found at /etc/UPower/UPower.conf
The lines/parameters in question are…
PercentageCritical=3
PercentageAction=2
Which I changed to…
PercentageCritical=6
PercentageAction=4
And either reboot the phone or restart the UPower service (sudo service upower restart
) for the changes to take effect.
or from the terminal…
sed -i -re 's/^(P.*Critical)=[0-9]/\1=6/' -e 's/^(P.*Action)=[0-9]/\1=4/' /etc/UPower/UPower.conf
sudo service upower restart