Ubuntu Battery Charge Threshold Setup Guide (Lenovo)

This guide covers setting up battery charge thresholds on Linux systems to extend battery life by limiting charging to a specific range (e.g., 75-85%).

This guide was written mostly by Warp.

This method was tested with Ubuntu 24.04.2.

Quick Reference

# Set thresholds manually
sudo sh -c 'echo 75 > /sys/class/power_supply/BAT0/charge_control_start_threshold'
sudo sh -c 'echo 85 > /sys/class/power_supply/BAT0/charge_control_end_threshold'

Step-by-Step Setup

1. Identify Your System

First, check your system manufacturer:

sudo dmidecode -s system-manufacturer
sudo dmidecode -s system-product-name

2. Check Available Battery Controls

# Check if battery threshold controls are available
ls -la /sys/class/power_supply/BAT0/ | grep threshold

Expected output should include:

charge_control_start_threshold
charge_control_end_threshold

3. Set Battery Thresholds

Method A: Lenovo/ThinkPad (Linux Power Supply Interface)

Check current settings:

echo "Start: $(cat /sys/class/power_supply/BAT0/charge_control_start_threshold)%"
echo "End: $(cat /sys/class/power_supply/BAT0/charge_control_end_threshold)%"

Set new thresholds (75-85% example):

sudo sh -c 'echo 75 > /sys/class/power_supply/BAT0/charge_control_start_threshold'
sudo sh -c 'echo 85 > /sys/class/power_supply/BAT0/charge_control_end_threshold'

Verify settings:

echo "Start: $(cat /sys/class/power_supply/BAT0/charge_control_start_threshold)%"
echo "End: $(cat /sys/class/power_supply/BAT0/charge_control_end_threshold)%"

4. Make Settings Persistent (Systemd Service)

Create a systemd service to maintain settings across reboots:

Create the service file:

sudo nano /etc/systemd/system/battery-charge-thresholds.service

For Lenovo/ThinkPad systems, add this content:

[Unit]
Description=Set Battery Charge Thresholds
After=multi-user.target

[Service]
Type=oneshot
ExecStart=/bin/sh -c 'echo 75 > /sys/class/power_supply/BAT0/charge_control_start_threshold'
ExecStart=/bin/sh -c 'echo 85 > /sys/class/power_supply/BAT0/charge_control_end_threshold'
RemainAfterExit=true

[Install]
WantedBy=multi-user.target

Enable and start the service:

sudo systemctl enable battery-charge-thresholds.service
sudo systemctl start battery-charge-thresholds.service

Verify the service is working:

sudo systemctl status battery-charge-thresholds.service

Troubleshooting

Common Issues:

Permission denied when writing to /sys/class/power_supply/:
- Make sure to use sudo and the sh -c wrapper
- Correct: sudo sh -c 'echo 75 > /sys/class/power_supply/BAT0/charge_control_start_threshold'
- Wrong: sudo echo 75 > /sys/class/power_supply/BAT0/charge_control_start_threshold
Thresholds reset after reboot:
- The systemd service wasn’t created or enabled properly
- Check service status: sudo systemctl status battery-charge-thresholds.service
Battery threshold files don’t exist:
- Your system may not support software-controlled charging thresholds
- Try using TLP or manufacturer-specific tools
- Some older systems don’t support this feature

Verification Commands:

# Check if your system supports battery thresholds
find /sys/class/power_supply/ -name "*threshold*" 2>/dev/null

# Monitor battery status
upower -i /org/freedesktop/UPower/devices/battery_BAT0

# Check current power supply information
cat /sys/class/power_supply/BAT0/status
cat /sys/class/power_supply/BAT0/capacity

Recommended Threshold Values

Conservative (maximize battery life): 40-80%
Balanced (good compromise): 75-85%
Performance (less restriction): 80-90%

Notes

Lower thresholds extend battery life but reduce available capacity
These settings primarily benefit systems that are plugged in frequently
Modern batteries have built-in protection, but software limits provide additional benefit
Some manufacturers (like ASUS) have their own specific tools and methods
Always test the method that works for your specific system and hardware configuration.
After I set this up, I’ve experienced a sudden crash several times when I unplugged the USB-C cable from my Lenovo laptop. It might have something to do with this configuration.

Thank you for reading this article!!