On older Linux OS versions, the system used to automatically suspend on low battery. Then this was managed by gsettings using
`gsettings set org.gnome.settings-daemon.plugins.power critical-battery-action 'suspend'`
But there have been some breaking changes (for the good) that has taken all of this out of any obvious control of the user. If you open /etc/UPower/UPower.conf , _you will see that the only option _CriticalPowerAction=HybridSleep . So Hybrid-Sleep/Hibernate/Shutdown are the only options on low power. Testing out hybrid-sleep (using sudo /usr/lib/systemd/systemd-sleep hybrid-sleep) does not do anything… which is unsurprising.
So what you need to do is switch HybridSleep to actually suspend. The way to do it is
Create a /etc/systemd/sleep.conf
[Sleep] > # And finally settings for hybrid-sleep -action > HybridSleepMode=suspend platform > HybridSleepState=mem > > > # Setting for suspend -action > SuspendState=mem disk #freeze > SuspendMode=suspend >> >
verify by running
sudo /usr/lib/systemd/systemd-sleep hybrid-sleep