A lightweight battery charge threshold manager for Linux laptops.

Threshd allows you to cap your laptop's battery charging at a specific percentage (e.g., 80%) to extend battery lifespan. It provides a system tray icon for easy access and runs as a secure system daemon.

• Simple UI - System tray icon with quick preset buttons
• Real-time updates - Shows current battery level and charging status
• Secure - PolicyKit integration for safe privilege elevation
• Lightweight - Written in C, ~100KB total binaries
• Fast - Builds in seconds

git clone https://github.com/mateohysa/threshd.git
cd threshd
./install-c.sh

That's it! The tray icon will appear automatically and start on future logins.

Not sure if your laptop is supported? Run ./check-hardware.sh first to verify.

The installation script will:

1. Check for required system dependencies
2. Build the daemon and tray application
3. Install system-wide with proper permissions
4. Enable and start the background daemon
5. Launch the tray icon

If you prefer manual control:

# Install dependencies (Ubuntu/Debian)
sudo apt install build-essential pkg-config libglib2.0-dev \
    libpolkit-gobject-1-dev libgtk-3-dev \
    libayatana-appindicator3-dev zenity

# Build
make

# Install (requires sudo)
sudo make install

# Enable daemon
sudo systemctl enable --now threshdd.service

# Start tray
threshd-tray &

Right-click the battery icon in your system tray to:

• Set threshold to 60%, 70%, 80%, or Uncapped (100%)
• Choose Custom... for any value between 60-100%
• View current battery percentage and threshold

The active threshold shows a ✓ checkmark.

Your laptop must support battery charge threshold control via sysfs:

ls /sys/class/power_supply/BAT*/charge_control_end_threshold

If this file exists, you're good to go! This feature is available on:

• Most ThinkPad models
• Many Dell, HP, and ASUS laptops
• Framework laptops
• And many others

Check your manufacturer's documentation or BIOS settings if unsure.

cd threshd
sudo make uninstall

┌─────────────────────────────────────────────────┐
│  threshd-tray                                   │
│  (GTK3 system tray - runs as user)              │
└────────────────┬────────────────────────────────┘
                 │
                 │ D-Bus
                 ↓
┌─────────────────────────────────────────────────┐
│  threshdd                                       │
│  (System daemon - runs as root)                 │
└────────────────┬────────────────────────────────┘
                 │
                 │ PolicyKit authorization
                 ↓
┌─────────────────────────────────────────────────┐
│  /sys/class/power_supply/BAT0/                  │
│    charge_control_end_threshold                 │
└─────────────────────────────────────────────────┘

# Clone the repository
git clone https://github.com/YOUR_USERNAME/threshd.git
cd threshd

# Build
make

# The binaries will be created:
# - threshdd (daemon)
# - threshd-tray (tray application)

# Check if running
pgrep threshd-tray

# Restart
pkill threshd-tray && threshd-tray &

# Check daemon status
sudo systemctl status threshdd.service

# View logs
sudo journalctl -u threshdd.service -f

If you get errors, your laptop may not support this feature. Check:

ls -l /sys/class/power_supply/BAT*/charge_control_*

If these files don't exist, your hardware doesn't support threshold control.

Contributions are welcome! Please feel free to submit a Pull Request. For major changes, please open an issue first to discuss what you would like to change.

# Build with debug symbols
make clean
make CFLAGS="-Wall -Wextra -g -DDEBUG"

# Run daemon manually for testing
sudo ./threshdd

# Run tray manually
./threshd-tray

threshd/
├── src/
│   ├── threshdd.c          # System daemon
│   └── threshd-tray.c      # Tray application
├── resources/              # Icons, D-Bus configs, PolicyKit policies
├── Makefile                # Build system
├── install-c.sh            # Installation script
└── README.md

MIT License - see LICENSE file for details.

• Linux kernel power supply subsystem maintainers
• The GTK and libayatana-appindicator projects
• Everyone who has contributed to making laptop battery management better

Note: Setting a charge threshold to 80% or lower can significantly extend your battery's lifespan by reducing stress on the cells. This is especially useful for laptops that stay plugged in most of the time.