How to set battery charging thresholds on laptop...

Fuzzbox

Member

Reaction score: 106
Messages: 62

"... or until you plug out / plug back in the battery from its compartment."
Removing the battery resets the battery controller on some Thinkpads.

Mine t440p stopped charging after I did the above 2 commands. :(
What do you mean by stopped charging ? What thresholds did you set and what is the current level of charge ?
 

ksiu

Member

Reaction score: 13
Messages: 93

What do you mean by stopped charging ? What thresholds did you set and what is the current level of charge ?

Code:
#!/bin/sh

acpi_call -p '\_SB_.PCI0.LPC_.EC__.HKEY.BCCS' -i 75

acpi_call -p '\_SB_.PCI0.LPC_.EC__.HKEY.BCSS' -i 85

The charge cable is plugged into the wall. The battery level is stuck at 79%. It is neither going up or down. Wierd. I expect it to charge up to 85% and stop.


$ acpiconf -i0
Design capacity: 56160 mWh
Last full capacity: 40510 mWh
Technology: secondary (rechargeable)
Design voltage: 10800 mV
Capacity (warn): 2025 mWh
Capacity (low): 200 mWh
Low/warn granularity: 1 mWh
Warn/full granularity: 1 mWh
Model number: 45N1147
Serial number: 340
Type: LION
OEM info: LGC
State: high
Remaining capacity: 79%
Remaining time: unknown
Present rate: 0 mW
Present voltage: 11702 mV

 

aragats

Daemon

Reaction score: 703
Messages: 1,618

The battery level is stuck at 79%. It is neither going up or down. Wierd. I expect it to charge up to 85% and stop.
That's correct, you set the "bottom" limit to 75%, it won't start charging until it goes below 75%. That's the expected behavior.
 

ksiu

Member

Reaction score: 13
Messages: 93

Read my previous post again :)

Charge stop threshold : the threshold your battery won't exceed when it's charging.
Charge start threshold : the threshold you have to reach before your battery starts charging again.

So, with a power source connected to you laptop, the battery will stay at 89% for now.
Disconnect the power source, you battery will discharge.
Connect the power source again : if the remaining capacity is higher than 15%, it won't charge; if it's lower than 15% it will charge, up to 95%.

So, if you want your laptop to be "almost charged all the time but not 100%", you should set a start charge threshold higher, like 85% for instance, and a stop charge threshold at 95%. But if you use it almost always connected to a power source, something like 30% / 75% is enough.

I hope that's clearer :)

Ok, solved. After reading the above by Fuzzbox, I think mine is working as intended.

So, when the battery is between the levels defined by "charge start" and "charge stop", the battery will still be charging but at a reduced rate (with just enough A/C juice to maintain the current battery level).
 

ksiu

Member

Reaction score: 13
Messages: 93

As someone who keeps his laptop near AC outlet 99% of the time, I am set start threshold and stop threshold to 50 and 60, respectively. I read somewhere it is best to keep Lithium battery in this range, to maximum battery longevity.

Question: is there a way to disable this threshold temporarily (allow the battery to charge to 100%)?
 

Fuzzbox

Member

Reaction score: 106
Messages: 62

Question: is there a way to disable this threshold temporarily (allow the battery to charge to 100%)?
No such option afaik (tlp indeed has it on Linux with the tlp fullcharge command). I did not manage to trigger a temporary full charge with acpi_call on FreeBSD.
You can only set new thresholds, like 98 start / 99 stop, to get a full charge. I guess we could script that to make it easier...
 

ksiu

Member

Reaction score: 13
Messages: 93

Removing the battery resets the battery controller on some Thinkpads.

It looks like removing the battery on my T440P does NOT reset the battery controller.

Is 0 and 100 the default values for the controller?


acpi_call -p '\_SB_.PCI0.LPC_.EC__.HKEY.BCCS' -i 0

acpi_call -p '\_SB_.PCI0.LPC_.EC__.HKEY.BCSS' -i 100
 
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