Battery percent limitter

[fregeauc]

I was thinking having the options in the battery settings to set a max charge other than 100% would be useful

[rcalixte]

There are a few problems with this. First is that this is only useful to users with batteries, i.e. mostly laptops. While they are more than common, it still means this development wouldn't matter for most desktop users. Second, and perhaps most important, each manufacturer has a different way to implement this and many of those approaches require elevated permissions. This effectively means a matrix of vendors to support and then maintain (because vendors change this functionality all the time). Some vendors also only allow the values for charge limits to be set in the BIOS, meaning that any software will have limitations regardless.

Until there is some sort of universal standard that most vendors choose to apply, this probably isn't conceivable. Your best bet if you want to implement this is to find the documentation for your vendor (if available) and then applying those settings locally if it is supported. This is what I have done for many machines, both past and present. Depending on the vendor, the charge limit might be configurable from the BIOS, a software tool they provide, the command-line, etc. Hopefully, there is an option that works for you.

[fosslover306]

I agree with @rcalixte, it is a great idea to extend the life of laptop batteries, unfortunately only Thinkpad batteries are supported in software as far as I know, and you need tlp and the correct kernel use that function in the first place without it causing kernel panics.

[arxo]

It's not just ThinkPads. I can set the battery charge limit on the command line on a Fujitsu notebook as well.
In both cases it works via piping the desired percentage into the file /sys/class/power_supply/XYZ/charge_control_end_threshold , with XYZ being some sting identifying the battery. On a Thinkpad I think it was BAT0 or BAT1, on the Fujitsu system it was CMB1 .
I'd say it's definitely worth looking into.

[fosslover306]

I was not aware of that trick, so if the power manager was able to expose the ability to set thresholds to the user and pipe it in automatically using the fact that power manager already knows how to find and identify the battery it could work on pretty much any laptop or battery in theory.

Does anyone have either the skills or a script laying around to do this? If so please share so the concept could be tried in practice.

Idea in mind is to run the script have it ask for a charge limit between 0-100% and automatically identify the config location and pipe the value into it.

[Jopp-gh]

Would it help if your computer could send a notification with beep once your battery drops below 20% or loads above 80% ?

What exactly would you expect to happen?

[rcalixte]

Would it help if your computer could send a notification with beep once your battery drops below 20% or loads above 80% ?

There's already an applet for this: BAMS

[Open-source-Neo]

I've created a simple program in python that does exactly what you're asking. You can check it on my repository

[fosslover306]

It asks me to set the lowest limit twice, and does this actually stop the charging process, or just notify the user?
Because I did get a notification my battery was too high, and is their a way to restore the default behavior?

Edit: I also checked the directory: /sys/class/power_supply/BAT0/charge_control_end_threshold, and nothing changed
and it instead created or accessed 0 byte files in /dev/pts.

[Open-source-Neo]

Just notify the user and ask to set a lowest value and highest value. At the moment there’s a visual bug that ask you to set the lowest value 2 times
You can set the lowest value and the highest the second time even if ask you to set the lowest again

[fosslover306]

So the first box sets the lowest value and the second one sets the highest value, Got it.

Thanks for clearing that up, I hope the bug can be fixed someday and it does work quite well for what it does.