install.sh

#!/usr/bin/env bash

if [ "$EUID" != '0' ]; then
	echo "This script must be run as root"
	exit 1
fi

# Or just run the parts below in the terminal as root!
mkdir -p '/var/lib/sd-battmgr/'
echo "Downloading script"
curl -fL https://gist.githubusercontent.com/WinkelCode/13be9bdec07f5f77a23b6181d580e6f6/raw/sd-battmgr.sh >'/var/lib/sd-battmgr/sd-battmgr.sh'
chmod +x '/var/lib/sd-battmgr/sd-battmgr.sh'
echo "Downloading systemd unit"
curl -fL https://gist.githubusercontent.com/WinkelCode/13be9bdec07f5f77a23b6181d580e6f6/raw/sd-battmgr.service >'/etc/systemd/system/sd-battmgr.service'
systemctl enable --now 'sd-battmgr.service'
sleep 2
systemctl status 'sd-battmgr.service'

sd-battmgr.service

[Unit]
Description=Steam Deck Battery Manager

[Service]
# Path to script, minimum charge, nominal charge
ExecStart='/var/lib/sd-battmgr/sd-battmgr.sh' 45 55
User=root
Restart=always

[Install]
WantedBy=multi-user.target

sd-battmgr.sh

#!/usr/bin/env bash
set -e

batctrl_path='/usr/share/jupiter_controller_fw_updater/RA_bootloader_updater/linux_host_tools/BatCtrl'

min_charge="$1"
[[ "$min_charge" =~ ^[0-9]+$ ]] || { echo "Error: Invalid minimum charge level: '$min_charge'"; exit 1; }
nom_charge="$2"
[[ "$nom_charge" =~ ^[0-9]+$ ]] || { echo "Error: Invalid nominal charge level: '$nom_charge'"; exit 1; }

if [ "$EUID" != '0' ]; then
	echo "This script must be run as root"
	exit 1
fi

log() {
	echo "$(date -Is) (Batt@${bat_level}%) $1"
}

sanity_checks() {
	[[ "$ac_status" =~ ^[01]$ ]] || { echo "Error: Unexpected value for ACAD/online: '$ac_status'"; exit 1; }
	[[ "$bat_status" =~ ^(Unknown|Charging|Discharging|Full)$ ]] || { echo "Error: Unexpected value for BAT1/status: '$bat_status'"; exit 1; }
	[[ "$bat_level" =~ ^[0-9]{1,3}$ ]] || { echo "Error: Unexpected value for BAT1/capacity: '$bat_level'"; exit 1; }
}

set_batt_mode() {
	case "$1" in
		'charge')
			if [ "$bat_status" = 'Charging' ]; then
				return
			fi
			log "Telling BatCtrl to charge"
			$batctrl_path ChargeMode 2 &>/dev/null
			;;
		'idle')
			if [ "$bat_status" = 'Unknown' ] || [ $bat_status = 'Full' ]; then
				return
			fi
			log "Telling BatCtrl to idle"
			$batctrl_path ChargeMode 1 &>/dev/null
			;;
		'discharge')
			if [ "$bat_status" = 'Discharging' ]; then
				return
			fi
			log "Telling BatCtrl to discharge"
			$batctrl_path ChargeMode 0 &>/dev/null
			;;
	esac
}

ac_loop() {
	if [ "$1" == 'init' ] && [ "$ac_status" = '1' ]; then
		log "AC adapter connected, starting normal operation"
	elif [ "$ac_status" = '0' ]; then
		log "AC adapter not connected, waiting for AC power"
		while [ "$ac_status" = "0" ]; do
			sleep 5
			get_pwr_state aconly
		done
		log "AC adapter connected, resuming normal operation"
	fi
}

get_pwr_state() {
	if [ "$1" != 'aconly' ]; then
		bat_status="$(cat /sys/class/power_supply/BAT1/status)"
		bat_level="$(cat /sys/class/power_supply/BAT1/capacity)"
	fi	
	ac_status="$(cat /sys/class/power_supply/ACAD/online)"
	sanity_checks
}


# Main loop
# ---------
echo "$(date -Is) Starting battery manager with min_charge='${min_charge}%', nom_charge='${nom_charge}%'..."
get_pwr_state
ac_loop init

while true; do
	get_pwr_state
	ac_loop

	case "$mode" in
		'charge')
			if [ "$bat_level" -ge "$nom_charge" ]; then
				log "Battery at or above nominal charge level (>=${nom_charge}%), switching to idle mode"
				mode="idle"
				set_batt_mode idle
			else
				set_batt_mode charge
			fi
			;;
		'idle')
			if [ "$bat_level" -lt "$min_charge" ]; then
				log "Battery below minimum charge level (<${min_charge}%), switching to charge mode"
				mode="charge"
				set_batt_mode charge
			else
				set_batt_mode idle
			fi			
			;;
		*)
			log "Initializing charge behavior..."
			if [ "$bat_level" -ge "$nom_charge" ]; then
				log "Init: Found battery at or above nominal charge level (>=${nom_charge}%), starting in idle mode"
				mode="idle"
				set_batt_mode idle
			elif [ "$bat_level" -lt "$min_charge" ]; then
				log "Init: Found battery below minimum charge level (<${min_charge}%), starting in charge mode"
				mode="charge"
				set_batt_mode charge
			else
				log "Init: Found battery in normal range (=${min_charge}%-${nom_charge}%), starting in idle mode"
				mode="idle"
				set_batt_mode idle
			fi
	esac
	sleep 5
done