calibrating a laptop battery

Matthias Apitz guru at
Fri May 17 07:05:32 UTC 2019


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' 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
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

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?


Matthias Apitz, ✉ guru at, +49-176-38902045
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May, 9: Спаси́бо освободители! Thank you very much, Russian liberators!

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