Laptop/ASUS

Include required module in initramfs

To work around cases of configuration failing to apply at boot because the required asus_wmi kernel module has not yet been loaded, configure early module loading for it.

TLP

TLP gained with version 1.4 the ability to set battery charge thresholds for laptops other than Thinkpads: see upstream documentation and example Gist.

bat

Another (more simple) way to force the charging threshold is by using bat-asus-battery-bin^AUR, which provides a bat-boot.service systemd service and an intuitive terminal interface to change the threshold by typing bat-asus-battery threshold value.

GNOME extension

gnome-shell-extension-battery-health-charging-git^AUR is a GNOME extension that "provides a graphical user interface for setting a laptop’s charging limit (charging threshold) within a Gnome environment". It supports ASUS laptops and many other brands. See its official website for details and screenshots.

systemd service

In order to automatically change the value at boot, create the following systemd service:

/etc/systemd/system/battery-charge-threshold.service

[Unit]
Description=Set the battery charge threshold
After=multi-user.target
StartLimitBurst=0

[Service]
Type=oneshot
Restart=on-failure
ExecStart=/bin/bash -c 'echo ''value'' > /sys/class/power_supply/BAT0/charge_control_end_threshold'

[Install]
WantedBy=multi-user.target

and then enable it.

Restart=on-failure and StartLimitBurst=0 are used to work around the service failing with a /bin/bash: /sys/class/power_supply/BAT0/charge_control_end_threshold: Permission denied error.

This error is due to the service being started before asus-wmi could be loaded by the kernel (noted as kernel: battery: new extension: ASUS Battery Extension in the journal), making it impossible to write there.

The combination of those two options allows unlimited restart of the service for DefaultStartLimitIntervalSec (set to 10 seconds by default in /etc/systemd/system.conf), leaving enough time for the sysfs path to become available and writable and thus ensuring the fastest execution of the service.

udev rule

The battery's charge_control_end_threshold power supply class attribute does not initially exist. It is added to the sysfs(5) directory by the asus-nb-wmi kernel module. Create a udev rule for asus-nb-wmi to set the battery's charge threshold:

/etc/udev/rules.d/asus-battery-charge-threshold.rules

ACTION=="add", KERNEL=="asus-nb-wmi", RUN+="/bin/bash -c 'echo ''value'' > /sys/class/power_supply/BAT?/charge_control_end_threshold'"

Persist after hibernation

While this setting will persist after suspending to RAM, it will be reset when resuming from hibernation. In order to re-execute the service after hibernation, use one of the methods described in Power management/Suspend and hibernate#Sleep hooks.

If creating a script as described in Power management/Suspend and hibernate#Hooks in /usr/lib/systemd/system-sleep, use something similar to:

/usr/lib/systemd/system-sleep/battery-threshold.sh

#!/bin/sh
case $1/$2 in
  pre/*)
    echo "Going to $2..."
    ;;
  post/*)
    echo "Waking up from $2..."
    echo 60 > /sys/class/power_supply/BAT0/charge_control_end_threshold
    ;;
esac

Do not forget to make the script executable.

Vivobook

# rmmod i2c-hid-acpi

# modprobe i2c-hid-acpi

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