I notice that macOS optimises charging for this scenario. Keeping the battery under 80% charge if you rarely disconnect it.

I’m surprised that the Linux distributions I use don’t do this automatically but I bet it could be configured.

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.

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.

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.

This is my second laptop running as a headless server. I had a shitty consumer i3 2nd gen latop running things just fine. Haven't had any battery hazards. And I live near the equator too.

I've used several laptops as file servers in hot apartments without AC and haven't had issues. The trick is to make sure you're not running a bunch of bloat you don't need (which is the root cause of 99% of "my old computer became slow") Slap something like debian on the laptop and don't even bother installing a desktop environment. The load of an NFS server sitting there idle most of the time and a few other system services doing basically nothing is negligible, any laptop should be able to handle it in 40 C weather. If not then you probably have some dust issues, so blow it out and see if the issue resolves itself. Keep the screen partially open (you can turn it off though) to help with ventilation.

I've never had any laptop die while operating like this. I only replace them when I replace my primary use laptop with something new, demoting my last primary use laptop to the server role.