Cap charging at 80% from the Power Panel

[iamteedoh]

The power panel already reads charge-start-threshold and charge-end-threshold, and switches to "Charge limit / Holding" when a cap is active. There is no way to set one. Today that means editing sysfs by hand or installing TLP.

I added a CHARGE LIMIT section with two buttons, 80% and Full.

The part worth discussing is that nothing in the UI runs as root. The button writes a small config file, a systemd .path unit notices the change, and a privileged oneshot applies it to charge_control_*. No polkit action, no password prompt, no setuid helper, and the panel never touches sysfs itself.

Persistence needs hooks because the thresholds live in EC firmware rather than kernel memory: a udev rule for boot and hotplug, and the unit for resume. I also re-assert on a timer, which is belt and braces rather than something I can point at a specific failure for.

It has been running on my machine for a day. Happy to open a PR if there is interest, or to hear if you would rather solve the privilege hop a different way.

[iamteedoh]

Adding this thread here since it's related but nothing ever progressed with that so this should still be a valid request/discussion: #627 (comment)

[krsna1729]

Related: opened #13205 with a UPower D-Bus take on this (passwordless EnableChargeThreshold toggle in the power panel, default ON). Noting the sysfs-based open PRs #12177/#11792 as alternatives — happy to converge on whichever approach maintainers prefer.

[daviddelven]

+1 for this. Hardware data point in case it helps whichever implementation lands:

• ASUS Zenbook UX331UN, Omarchy 4.0.4, kernel 7.2.5-3-omarchy
• asus_wmi / asus_nb_wmi loaded, and /sys/class/power_supply/BAT0/charge_control_end_threshold is exposed (currently 100)
• No asusctl or TLP installed, so a panel toggle writing the sysfs threshold directly would cover this machine without extra packages.