⚡️ Auto Switch Power Profiles on AC/Battery

[webbegg]

This guide explains how to configure your Arch Linux laptop to automatically switch power profiles (via power-profiles-daemon) depending on whether your charger is connected or not.

• On AC: set performance
• On Battery: set power-saver
• Works at boot (via systemd) and hotplug (via udev)

---

✅ Requirements

• Arch Linux (or derivative)
• power-profiles-daemon installed (pacman -S power-profiles-daemon)

---

🔎 Step 1. Identify Your AC Adapter Name

Run:

ls /sys/class/power_supply/

Typical output:

AC  BAT0

or

ACAD  BAT1

⚠️ Warning: The AC adapter name varies (AC, ACAD, AC0, etc).
Remember yours, you’ll need it in the udev rule.

---

📝 Step 2. Create the Auto-Switch Script

Save as /usr/local/bin/power-profile-auto.sh:

#!/usr/bin/env bash
# Auto switch power-profiles-daemon profiles based on AC adapter state
# Requires: power-profiles-daemon, systemd

# ⚠️ Change this if your adapter name differs!
AC_PATH="/sys/class/power_supply/AC/online"

set_profile() {
    case "$1" in
        "1") # AC connected
            powerprofilesctl set performance
            ;;
        "0") # AC disconnected
            powerprofilesctl set power-saver
            ;;
    esac
}

if [[ -f "$AC_PATH" ]]; then
    AC_STATE=$(cat "$AC_PATH")
    set_profile "$AC_STATE"
else
    echo "⚠️ Adapter path not found: $AC_PATH" | systemd-cat -t power-profile-auto -p warning
fi

Make executable:

sudo chmod +x /usr/local/bin/power-profile-auto.sh

---

⚙️ Step 3. Create a Udev Rule

Create /etc/udev/rules.d/99-power-profile.rules:

# ⚠️ Replace "AC*" with your adapter name if necessary
SUBSYSTEM=="power_supply", KERNEL=="AC*", ACTION=="change", RUN+="/usr/local/bin/power-profile-auto.sh"

Reload rules:

sudo udevadm control --reload-rules
sudo udevadm trigger

You can test events with:

udevadm monitor --udev

---

🖥 Step 4. Create a Systemd Service (Boot-time)

Create /etc/systemd/system/power-profile-auto.service:

[Unit]
Description=Set power profile based on AC state at boot
After=multi-user.target

[Service]
Type=oneshot
ExecStart=/usr/local/bin/power-profile-auto.sh

[Install]
WantedBy=multi-user.target

Enable it:

sudo systemctl enable power-profile-auto.service

---

🚀 Done!

Now your laptop will:

• Apply the correct power profile at boot
• Dynamically switch profiles when you plug/unplug the charger
• You can always force the power profile manually as usual

[frigo1337]

Worked flawlessly, thank you!

[c4software]

Nice ! I think it could be built-in without any trouble.

What do you think @dhh ?

[dhh]

I'd like to have this built-in, yeah 👌

[c4software]

@webbegg, I let you propose a PR. If you can’t, I can also do it.

[webbegg]

I think it would be better if you propose the PR, as I just installed the distribution a few days ago and I’m still familiarizing myself with the structure. I’m looking forward to seeing your approach for future contributions. Thank you!

[c4software]

No problem, I’ll do it tomorrow 👍.

[ramtinJ95]

On this topic, is it possible to somehow limit the charge on AC to 80% so we save some battery health somehow? Its one of the few things im missing with Omarchy/Arch right now

[ramtinJ95]

Yeah for TLP i had to set this config variable like this:
DEVICES_TO_DISABLE_ON_BAT_NOT_IN_USE=""

And i even went a bit further just to be sure that wifi nevers gets off:
RUNTIME_PM_DRIVER_DENYLIST="mei_me nouveau radeon xhci_hcd ath11k_pci"
where the last option is my wifi card, not sure its necessary really.

Now I could create a PR for these things + battery charge thresholds so it stops at like 80% to save battery health. But Omarchy is shipping with power-profiles-daemon where im not sure these things are possible. Are you open to change it to TLP?

[c4software]

In my opinion we should stick to power-profiles-daemon, it's less configurable. But widely compatible OOB.

[webbegg]

I checked out the whole battery charge limit thing and I think I’ve got it working. I set it to 80%, but it was a bit trickier on my MacBook 11,4 since the installation doesn’t come with this feature by default. On a “normal” laptop it should be as simple as adding 80 to the /sys/class/power_supply/BAT0/charge_control_end_threshold file.

Steps to make it work on a MacBook 11,4

# prerequisites
sudo pacman -Syu dkms base-devel linux-headers git

# install applesmc-next via AUR (example using yay)
yay -S applesmc-next-dkms

# reboot to load the new module
sudo reboot

[dhh]

Yeah, I don't really want to switch this over. I just want to fix the bug where wifi/audio/usb stuff is turned off and you have to use rfkill to get them back!

[ramtinJ95]

Can confirm this is correct, it is very possible to modify those files without tlp and set the battery stuff. Although you should probably set a threshold for when to start charging at like 75% or something so it does not keep charging from 79 to 80, but that setting is at almost the same place as the one you modifed 😄

[wizards-are-cool]

It works perfectly! Thank you!

[prem-charan]

worked perfectly for me too!! thanks a lot ❤️

[Popidge]

Excellent, worked great!

Depending on your hardware and BIOS (thank you HP /s), you may not have a "performance" mode, or you may have different modes available.

Running powerprofilesctlwill show you power modes available:

~ ❯ powerprofilesctl
  balanced:
    PlatformDriver:	placeholder

* power-saver:
    PlatformDriver:	placeholder

which you can drop into your auto-switch script as above (I used "balanced" for AC power)

[aguimaraes]

This worked flawlessly on my Thinkpad p14s.
Thank you