Stay in battery mode when charging with external USB-C PD Power Bank

[norpol]

Is your feature request related to a problem? Please describe.

When I'm using my USB-PD PowerBank I'd like to stay in the battery configuration and perhaps also stop charging the internal battery altogether. Unfortunately the PowerBank doesn't show up differently when looking at the udevadm monitor or lsusb output, but perhaps there are other power banks that share a USB identifier before negotiation the power delivery.

Describe the solution you'd like

A clear and concise description of:

• When I'm connected to an external power bank
• I'd like to stay in power-save mode
• And disable charging of the internal battery

Describe alternatives you've considered

An alternative would be a way to send tlp a message to switch to a certain configuration, perhaps via udevadm trigger or dbus?

Alternative is to just run sudo tlp bat to switch to the battery mode and setting the charge settings with tlp or /sys/class/power_supply/BAT0/charge_control_end_threshold manually.

Alternative workaround for now. Run powerbank before or when connecting to a USB powerbank.

• disables charging (except if you're really low on battery)
• sets tlp to manual bat mode with tlp bat
• listens with udev-monitor for the charger to disconnect
• restores charging limits to previous mode
• restores tlp to auto mode tlp start
• Script uses sudo for when sudo is needed, alternatively remove sudo altogether and start the script with sudo itself

#!/usr/bin/env bash
set -ueo pipefail
bat="/sys/class/power_supply/BAT0/"
start="$(cat "${bat}/charge_control_start_threshold")"
end="$(cat "${bat}/charge_control_end_threshold")"

echo "0" | sudo tee "${bat}/charge_control_start_threshold"
echo "5" | sudo tee "${bat}/charge_control_end_threshold"

sudo tlp bat

UPOWER_AC_DEVICE='/org/freedesktop/UPower/devices/line_power_AC'

# props https://github.com/alba4k/.dotfiles/blob/e723af501e033e1e440a043f13616a301d72f675/.config/hypr/ac_detect.sh#L6
_ac_connected() {
    dbus-monitor --system "type='signal',
            sender='org.freedesktop.UPower',
            path='$UPOWER_AC_DEVICE',
            interface='org.freedesktop.DBus.Properties',member='PropertiesChanged'" \
    |& grep --line-buffered -oP 'boolean \K.*$'
}

while read -r connected; do
    if [ "${connected}" == "false" ]; then
        echo "AC disconnected"
        break
    elif [ "${connected}" == "true" ]; then
        echo "AC connected"
        continue
    else
        echo "AC unknown"
        break
    fi
done < <(_ac_connected) # break in while does not work if you pipe into `read -r`

echo "Restore previous tlp"
echo "${start}" | sudo tee "${bat}/charge_control_start_threshold"
echo "${end}" | sudo tee "${bat}/charge_control_end_threshold"
sudo tlp start