calibrating a laptop battery

[Matthias Apitz]

Hello,

Background: I have an Acer C720 netbook (selled as a so called
Chromebook, but running CURRENT fine) and after some year of usage
(since 2015) I bought a new battery, original from Acer (as least
claimed by the dealer as original). When the battery was installed,
FreeBSD showed this with 'sysctl -n hw.acpi.battery.life' as 100%
charged. I was told, I have to 'calibrate' it with the procedure: let it
run out of energy without power supply, and charge it again to 100%.
But magically it charges only up to 75% when the blue LED says "fully
charged", and each day this point goes up 1% more, i.e. LED goes blue
next day with 76%, the day after 77% and so on until somewhere around
96%. When I fully discharge it again (i.e. using it on the road until
nearly power-off), this process starts again with 75%.

I was told in a thread in the Acer forum
https://community.acer.com/en/discussion/567420/acer-c720-battery-hassles
a lot of things, even Windows hints (I saif FreeBSD) or a magic hole in the 
bottom of the case (which is not there in the Acer C720) and among
others they pointed to an Ubuntu tool
http://manpages.ubuntu.com/manpages/xenial/man8/power-calibrate.8.html

Questions:
1) What does the word "calibrate battery" means technically?
2) Do we have something in FreeBSD to do 1)
3) Any other ideas about this issue?

Thanks

	matthias
-- 
Matthias Apitz, ✉ guru at unixarea.de, http://www.unixarea.de/ +49-176-38902045
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