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tlp - power management, force BAT0 while AC plugged in

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cspl
Posts: 2
Joined: 2022-01-20 10:38

tlp - power management, force BAT0 while AC plugged in

#1 Post by cspl »

Hi, I'm using Bullseye on T520. I used to have tp_smapi working, however the "start_charge_threshold" feature no longer works.
I'm currently trying to use tlp. This program works fine but I cannot figure out on of the use cases: I want to force running on battery.
I want the machine to start charging at 25% and stop charging at 90% and have battery mode the default regardless of AC being available, i.e: I want to force the default use of battery instead of the AC.
I cannot figure out it is even possible to "switch off" AC but leave the power adapter plugged in.
Is there a way to achieve that? I don't mind if I have to script it myself. Any ideas/suggestions?

cspl
Posts: 2
Joined: 2022-01-20 10:38

Re: tlp - power management, force BAT0 while AC plugged in

#2 Post by cspl »

OK, my findings in case anybody is looking for this.
Quoting: https://linrunner.de/tlp/faq/battery.html

1. You cannot change the basic behavior described above, because it is hard-coded into the EC firmware by the vendor. However, you can control it by setting thresholds using TLP.
2. What charge thresholds do not do
They do not exercise any control over the discharging of the battery, this depends solely on whether AC is connected and if the laptop is switched on

And:
External kernel module packages would thus become superfluous. However, the kernel patches for charge_behaviour are in the review process and have not yet been merged (as of kernel 5.16).

I am missing that charge_bahaviour, but there's hope: https://lore.kernel.org/all/20211113104 ... schuh.net/
tpacpi-bat claims to do that via acpi_call and there's one more discussion on the possible kernel patch.

LE_746F6D617A7A69
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Re: tlp - power management, force BAT0 while AC plugged in

#3 Post by LE_746F6D617A7A69 »

cspl wrote: 2022-01-20 10:47 I want the machine to start charging at 25% and stop charging at 90% and have battery mode the default regardless of AC being available (..)
Where did You get those numbers (percentage) ?

Most of the batteries don't like deep discharge levels with DOD (Depth Of Discharge) > 50%.
This applies to all batteries older than Li-Ion/LiFePo4 technologies, and Your laptop for sure has a NiMh battery, which is even less tolerant to deep discharge levels.
Bill Gates: "(...) In my case, I went to the garbage cans at the Computer Science Center and I fished out listings of their operating system."
The_full_story and Nothing_have_changed

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