notebook is a 10 year old macbook pro without macos I installed xubuntu 24.04 in. It comes with an embedded battery.
First notebook I bought, not from apple, had a removable battery. The vendor told me to maximize its life I shouldn’t plug the battery in, unless I need it (like for traveling). This way, I’ve managed to keep the original battery in good working condition for 8 years so far.
Back to the macbook: I cannot remove the battery and constantly loading it to up to 80% and discharge it up to 20% seems ridiculous. Furthermore, this would deplete the battery even faster, I believe.
What can I do to spare the battery as much as possible?
10+ years old laptop batteries have a habit of dying eventually. And some of them (not many) cause a fire then - especially while charging up.
I have seen it - well, 3 hours later in the morning then.
I would not leave this device alone with the power cord plugged in. Charge it only while you are there, so you recognize it, if it decides to heat up someday. Then have a metal bucket ready to carry it outside.