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by rn00m

How to Fix a Stuck 80% Battery Charge Limit on Linux Mint (Lenovo ThinkPad)

Relic Recovery Log: 80% Battery Charge Limit

Overview

If you previously set an 80% battery charging threshold on Windows (using Lenovo Vantage or Windows Power Management) and then wiped the drive to install Linux Mint, your laptop might still stop charging at 80%.

This happens because Windows writes the threshold restriction directly into the laptop’s hardware embedded controller (EC). The setting persists even after changing operating systems.

Here is how to clear the limit and restore 100% charging capacity natively using Linux Mint.

Prerequisites

Lenovo ThinkPads require a specific kernel module extension to allow Linux to talk directly to the hardware’s power controllers. Install it first via your terminal:

sudo apt update
sudo apt install acpi-call-dkms

Step-by-Step Fix

1. Install TLP (Advanced Power Management)

TLP is a feature-rich command-line utility for Linux that manages battery saving and thresholds.

sudo apt install tlp tlp-rdw

2. Update the TLP Configuration File

You must configure TLP to target a 100% stop threshold, overriding the residual Windows firmware lock.

  1. Open the configuration file in your terminal text editor:
sudo nano /etc/tlp.conf
  1. Scroll down (or press Ctrl + W to search) until you locate the BAT0 threshold lines. 3.Remove the # symbol from the beginning of the lines to uncomment them, and change the values to 0 and 100:
# Battery charge level below which charging will begin.
#START_CHARGE_THRESH_BAT0=75
# Battery charge level above which charging will stop.
#STOP_CHARGE_THRESH_BAT0=80

# BAT1: Secondary / Ultrabay / Slice / Replaceable battery
# Note: primary on some laptops
# Default: <none>

# Battery charge level below which charging will begin.
#START_CHARGE_THRESH_BAT1=75

and change the values on the respective lines to:

START_CHARGE_THRESH_BAT0=0
STOP_CHARGE_THRESH_BAT0=100
  1. Save and exit the editor by pressing Ctrl + X, then Y, then Enter.

3. Apply Changes and Force Full Charge

Now, trigger TLP to read the new configuration file and explicitly force the battery past its hardware lock:

# Restart TLP to apply the 100% limit configuration
sudo tlp start

# Force the battery hardware to charge completely to full
sudo tlp fullcharge

Your battery will now bypass the old 80% rule and charge all the way up to 100%.

Troubleshooting Fallback

If the terminal commands do not override the threshold on your specific ThinkPad generation, you can change it directly at the hardware layer:

  1. Reboot the laptop and tap F1 repeatedly at the Lenovo logo to enter the BIOS.
  2. Navigate to Config > Power.
  3. Disable Battery Charge Threshold (or set it manually to 100%).
  4. Press F10 to save changes and exit.