Problem setting max charge threshold with tlp on thinkpad L590 on Ubuntu 20.04

Solution 1:

This is a known firmware issue. From to the FAQ

Charge thresholds shown by tlp-stat -b do not correspond to the configured ones

ThinkPad Edge, E / L / S series, SL410/510, Yoga series

On these models the threshold values shown by tlp-stat -b do not correspond to the written values.

For example the setting

START_CHARGE_THRESH_BATx=75
STOP_CHARGE_THRESH_BATx=80 

shows 75 / 74. The described behavior is caused by the firmware (UEFI/BIOS), not by TLP.

Nonetheless the charge thresholds work as configured.