Laptop batteries wear out over time. Keeping one at 100% for long periods can add unnecessary stress.

If you mostly use your laptop at a desk, a charging threshold is a simple way to reduce that wear.

What is a charging threshold?

A charging threshold controls when charging starts and stops:

Start charging: 40%
Stop charging: 80%

The laptop charges to 80%, then starts again when the battery falls below 40%. Charge to 100% before travelling when you need the extra runtime.

Configure a threshold with TLP

TLP can manage power settings on Linux. On Debian and Ubuntu-based distributions:

sudo apt install tlp
sudo systemctl enable --now tlp

Check the battery and TLP status:

sudo tlp-stat -s
sudo tlp-stat -b

If thresholds are supported, edit /etc/tlp.conf:

START_CHARGE_THRESH_BAT0=40
STOP_CHARGE_THRESH_BAT0=80

Apply and verify the change:

sudo tlp start
sudo tlp-stat -b

Check hardware support

Not every laptop supports charging thresholds. Support depends on the model, firmware, and Linux kernel. Run sudo tlp-stat -b to check.

The short version

For a laptop that stays plugged in, start with 40–80%:

Normal desk use:       40–80%
Before travelling:    charge to 100%
Back at the desk:      40–80%

Use 100% when you need maximum runtime. A threshold is an optional optimization, not a rule.