Allow intel-undervolt to be executed on AC to Battery and Batter to AC change ensuring proper undervolting.

99-powertargets.rules

SUBSYSTEM=="power_supply", KERNEL=="AC", ATTR{online}=="0", RUN+="/bin/systemctl start battery.target"
SUBSYSTEM=="power_supply", KERNEL=="AC", ATTR{online}=="1", RUN+="/bin/systemctl start ac.target"

ac.target

[Unit]
Description=On AC power
DefaultDependencies=no
StopWhenUnneeded=yes

battery.target

[Unit]
Description=On battery power
DefaultDependencies=no
StopWhenUnneeded=yes

intel-undervolt-loop.service

[Unit]
Description=Intel Undervolt Loop Service
After=multi-user.target

[Service]
Type=simple
ExecStart=/usr/bin/intel-undervolt daemon
ExecReload=/bin/kill -USR1 $MAINPID

[Install]
WantedBy=multi-user.target

intel-undervolt.conf

enable no

undervolt 0 'CPU' -20
undervolt 1 'GPU' 0
undervolt 2 'CPU Cache' -20
undervolt 3 'System Agent' 0
undervolt 4 'Analog I/O' 0

power package 65/5 55/60

tjoffset -10

interval 30000

daemon undervolt:once
daemon power
daemon tjoffset

intel-undervolt.service

[Unit]
Description=Intel Undervolt Service
After=multi-user.target suspend.target hibernate.target hybrid-sleep.target

[Service]
Type=oneshot
ExecStart=/usr/bin/intel-undervolt apply

[Install]
WantedBy=multi-user.target suspend.target hibernate.target hybrid-sleep.target ac.target battery.target