Preserving your Linux laptop battery health

by limiting its charge to 90%

If you, like me, use KDE, then in System Settings -> Power Management -> Advanced Power Settings you might've noticed an option to stop charging your battery when it reaches some percentage (and also to start charging only once below some other percentage). Personally, I've set one of them to 90%, and another one - to 80%.

However, you might've noticed that this setting, while working nicely, seems to be not preserved over reboots. There is a closed discussion on Manjaro forums and an article on ArchWiki about it.

From there, you might find a workaround: just make a systemd service to set these settings for you after reboot!

1. Create a file /etc/systemd/system/battery-charge-threshold.service with content like this:

    [Unit]
    Description=Set the battery charge threshold
    After=multi-user.target
    StartLimitBurst=0
   
    [Service]
    Type=oneshot
    Restart=on-failure
    ExecStart=/bin/bash -c 'echo 90 > /sys/class/power_supply/BAT0/charge_control_end_threshold && echo 80 > /sys/class/power_supply/BAT0/charge_control_start_threshold'
   
    [Install]
    WantedBy=multi-user.target
   

2. Run the following commands to enable it:

    sudo chmod 644 /etc/systemd/system/battery-charge-threshold.service
    sudo systemctl daemon-reload
    sudo systemctl enable battery-charge-threshold.service
   

3. Enjoy extended life of your laptop battery... maybe... for the price of shorter "laptop life from one charge", hehe