How to adjust charging thresholds of laptop battery?

Question

My laptop is Lenovo T400, and OS is Ubuntu 12.04.

I have not been able to adjust the thresholds for battery starting charging and stopping charging. I observed that its current starting charging threshold is about 40%, and stopping charging threshold is about 60%. I forgot if it was me and which program I used to control the battery to stop charging at 60% and start charging at 40%.

I followed my previous post https://askubuntu.com/questions/58789/how-to-check-charged-percentage-of-battery-and-to-adjust-its-thresholds, but I don't find /sys/devices/platform/smapi. Also I have /proc/acpi/battery/BAT0/, but I have only three files alarm, info and state.

I want to adjust the thresholds. So I wonder how to do that?

Answer 1

Newer Lenovo ThinkPads (such as my E540) are not compatible with tp_smapi-dkms. Fortunately I found that the TLP utility can use different modules -- such as the tp_smapi OR the thinkpad_acpi DKMS modules -- to communicate the thresholds to the battery. Other Lenovo laptops may communicate with the battery using the acpi_call kernel module.

Note: when kernel 5.17 is available to you, it will have a new kernel module called natacpi which eliminates the need for tp_smapi. Furthermore, recent versions of TLP support charging thresholds in a few additional manufacturers' hardware.

Nowadays TLP is available via standard Ubuntu or Debian repositories. (Though you may benefit from the latest version available using TLP website to install the packages.)

After installing TLP, set the battery charge thresholds using two lines in the configuration file /etc/default/tlp

START_CHARGE_THRESH_BAT0=65
STOP_CHARGE_THRESH_BAT0=80

This example tells TLP to set the battery thresholds to start charging at 65% and stop charging at 80%. I find that the thresholds persist correctly even when booting into a different OS that doesn't have TLP installed. (Though I presume if you booted into Windows or another OS that DOES have power management tools installed, that OS might overwrite the previously set charge thresholds.)

To TEMPORARILY bring the battery to a full charge, issue the following terminal command:

 $ sudo tlp fullcharge

The battery will then charge to its maximum capacity, and revert to the previous thresholds afterwards.

Note: If your laptop is not a "ThinkPad," TLP probably cannot set your battery charge levels. However, recent versions have added support for additional brands and models.

If your vendor supplies a power management utility for Windows, you can probably boot using some form of Windows to set the battery charge levels and then reboot into linux. In my experience, the battery charge threshold settings persist after system reboots.

Answer 2

You need to install tp_smapi-dkms, just do

apt-get install tp_smapi-dkms

When finished, use lsmod | grep tp_smapi to check if module is loaded, to adjust the charge thresholds, do something like this

echo 40 > /sys/devices/platform/smapi/BAT0/start_charge_thresh
echo 60 > /sys/devices/platform/smapi/BAT0/stop_charge_thresh

Add these lines to /etc/rc.local to run them at boot.

This module works at least on X220.

Answer 3

On my laptop (Yoga 260) I had to get acpi-call-dkms, which provides the acpi_call kernel module:

sudo apt install tlp acpi-call-dkms
sudo tlp setcharge 40 60 #set the start and stop thresholds to 40% and 60%

Output of sudo tlp stat -b:

--- TLP 1.1 --------------------------------------------

+++ ThinkPad Battery Features
tp-smapi   = inactive (unsupported hardware)
tpacpi-bat = active

+++ ThinkPad Battery Status: BAT0 (Main / Internal)
/sys/class/power_supply/BAT0/manufacturer                   = SMP
/sys/class/power_supply/BAT0/model_name                     = 00HW027
/sys/class/power_supply/BAT0/cycle_count                    = (not supported)
/sys/class/power_supply/BAT0/energy_full_design             =  44000 [mWh]
/sys/class/power_supply/BAT0/energy_full                    =  37970 [mWh]
/sys/class/power_supply/BAT0/energy_now                     =  18910 [mWh]
/sys/class/power_supply/BAT0/power_now                      =      0 [mW]
/sys/class/power_supply/BAT0/status                         = Unknown (threshold effective)

tpacpi-bat.BAT0.startThreshold                              =     40 [%]
tpacpi-bat.BAT0.stopThreshold                               =     60 [%]
tpacpi-bat.BAT0.forceDischarge                              =      0

Charge                                                      =   49.8 [%]
Capacity                                                    =   86.3 [%]

Answer 4

Sounds to me like your TLP settings were changed somehow and now you would like to change them back. The TLP ArchWiki is pretty good even if you don't use Arch: https://wiki.archlinux.org/index.php/TLP

To install TLP, open a terminal and enter:

sudo apt install tlp

There's also now a GUI for TLP which will make these settings easier to change. To install the UI tool we first need to add the repository:

sudo add-apt-repository ppa:linuxuprising/apps

Then install TLPUI via:

sudo apt install tlpui

Run TLPUI from the Applications menu and change the stop and start charge thresholds. These can be found at the very bottom under "ThinkPad Battery". Note that these options are available only for ThinkPads.

Change the START_CHARGE_THRESH_BAT0 to something reasonable like 75% and change the STOP_CHARGE_THRESH_BAT0 to something higher like 80 or 90% or even 100% if you like to fully charge your battery.

Reference: Improve Battery Life in Ubuntu 18.04 / Higher

Answer 5

For LG Gram laptops, there's a specific kernel driver, which seems to be active out of the box, at least in EndeavourOS, for particular features of LG Gram, see the kernel docs.

In particular, it also provides a "Battery care limit". Quoting from that page:

Writing 80/100 to /sys/devices/platform/lg-laptop/battery_care_limit sets the maximum capacity to charge the battery. Limiting the charge reduces battery capacity loss over time.

This value is reset to 100 when the kernel boots.

So, for example, you can manually set the limit to 80 with the following command:

echo '80' | sudo tee /sys/devices/platform/lg-laptop/battery_care_limit

I tested that on my LG Gram 16, and it seems to work perfectly: when plugging the AC with 85% charged, KDE states that it is charging, but the percentage stays at 85% (with "time to full" blocked at 1:41).

As stated in the quote above, this value will be reset when the kernel boots, so you may have to change the value again.

I guess that for a more automatic solution, tlp provides support for that as well.