Good point, and good feature.

If I'm to believe this bug report [1], KDE actually offers throttling charge, but I suspect the Linux kernel lacks support for this kind of stuff for many laptops, maybe also because sometimes the laptop itself does not support this.

Apparently, one should be able to see these files on a supported laptop:

   /sys/class/power_supply/BAT0/charge_control_start_threshold
   /sys/class/power_supply/BAT0/charge_start_threshold
   /sys/class/power_supply/BAT0/charge_stop_threshold

I don't have them on the HP EliteBook G6 laptop I'm currently using.

But thanks for reminding me this. I was considering using an original PinePhone as a Bluetooth receiver. Unfortunately, Wifi and Bluetooth require a battery to be present in this phone and I was a bit concerned leaving it plugged in at all times. I'll need to check if the kernel the hardware and support this. Still a bit concerned that the battery will be wearing out fast, I'm afraid Bluetooth will be using the battery power even if the phone is plugged, which is a bummer.

I don't have those on my Dell XPS13 Developer Edition 9370 either.

Would be interesting to know which chipsets support it.

You can hack that on any system that lets you read the battery status. All you need is a smart plug. You power the laptop from the smart plug. You switch off the plug when the battery is at 80% and you switch it on again when it's at 20%.

This has a major drawback: it's constantly using battery cycles.

Does a computer with charging throttle like described draw power from battery too, or does it use the power from the plug directly?

I know that there are laptops that bypass the battery if plugged into the mains but I think that the answer varies case by case.

A battery level check every five minutes should be more than enough, not a big draw from the battery for a laptop.

I don't think there's any standard interface for the laptop to control its charging.

Frame.work laptops have a firmware setting to stop charging at 90%, to extend battery life.