Ubuntu – How to disable automatic screen dimming when the wireless mouse has low battery

18.04batterybrightnessmousepower-management

Similarly to this question, I find that when a wireless mouse with low battery is plugged into a laptop running Ubuntu 18.04 on battery power, the screen automatically dims after 15 seconds of inactivity, even if the Power setting "Dim screen when inactive" is set to "Off". This doesn't make any sense to me – why would the dimming the screen help preserve power in the mouse?

15 seconds is very inconveniently short – how can I disable this automatic screen dimming? I do not have any power management programs like jupiter or tlp installed. This answer suggests running

gsettings set org.gnome.desktop.session idle-delay <seconds>

on the terminal, but that doesn't change anything for me. Disabling DPMS as suggested in this answer doesn't work either. The only thing that works is unplugging the mouse and restarting my computer, which is obviously kind of annoying.

Best Answer

Read your current value :

gsettings get org.gnome.settings-daemon.plugins.power idle-dim
gsettings get org.gnome.settings-daemon.plugins.power idle-brightness

Then try :

gsettings set org.gnome.settings-daemon.plugins.power idle-dim false

Or if this do not work, try different values for org.gnome.settings-daemon.plugins.power idle-brightness

org.gnome.desktop.session idle-delay is just the delay before the screensaver activates !


I guess the system see your mouse battery as a laptop battery. Udev handles peripherals and power supplies, so it is the first suspect. Sorry I cannot give you a clear solution right now, we have to find a clue of what is wrong first. Post these details, I hope it will help :

  • What is the content of /sys/class/power_supply/ when the mouse is plugged and when it is not ?
  • Run sudo udevadm monitor -p. This will monitor events, so you need to plug the mouse after. Check if the output is the same when the battery is high or low.
  • Run sudo journalctl --since=-2m just after plugging the mouse. Likewise, check if the output is the same when the battery is high or low.