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#1 2014-08-21 08:05:55

dice
Member
From: Germany
Registered: 2014-02-10
Posts: 408

battery capacity higher than possible

I have a Lenovo E540 and my battery reports a higher max capacity than the max capacity by design.

% cat /sys/class/power_supply/BAT0/energy_full
42360000
% cat /sys/class/power_supply/BAT0/energy_full_design
40400000

Is this a kernel bug or something? Or has it to do with some config I don't know of?

And most important: could it hurt my battery? I mean would it get overcharged because of this?

Lots of questions...I tried to search but it is quite rare that people are complaining about their battery having too high capacity.
When the battery was brand new it had its design capacity. Never heard of a battery that increases its capacity over time. That would solve a lot of problems!:D


I put at button on it. Yes. I wish to press it, but I'm not sure what will happen if I do.  (Gune | Titan A.E.)

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#2 2014-08-21 09:09:27

kokoko3k
Member
Registered: 2008-11-14
Posts: 1,482

Re: battery capacity higher than possible

Well, i'm having the same with a replacement battery.
If there is a problem, i think it lies in the firmware battery or something similar, till now (one year so far) it never went down. THAT is strange...

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#3 2014-08-21 14:44:01

emeres
Member
Registered: 2013-10-08
Posts: 1,570

Re: battery capacity higher than possible

Can you overwrite those values? Do they recover after reboot? (Untested, might be risky)

Last edited by emeres (2014-08-21 14:44:21)

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#4 2014-08-21 16:00:23

dice
Member
From: Germany
Registered: 2014-02-10
Posts: 408

Re: battery capacity higher than possible

No, it is not possible to write to these values.
They have no write permission for anyone. If I chmod e.g. energy_full and try

echo "40400000" > /sys/class/power_supply/BAT0/energy_full

the root session (with su) gets killed and core dumped.


I put at button on it. Yes. I wish to press it, but I'm not sure what will happen if I do.  (Gune | Titan A.E.)

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