Arch Linux

snack

Member

From: Italy

Registered: 2009-01-13

Posts: 893

Weird battery behavior

I bought a new battery for my wife's laptop (HP  Pavilion G6), not an official HP spare part but one from a third party producer declared as compatible by the seller. The battery has been in use for some months but since the beginning it had some issues with duration (I didn't really monitored the behavior since it's not my laptop). Currently, at boot there is a prompt warning message saying that the stated battery capacity is below the very low level and that it has to be replaced. Booting anyway, the autonomy is barely sufficient to start the OS (2-3 minutes), even if the battery has been in charge for hours. I tried to boot with a Linux live CD (the native OS is Win10) and acpi reports a full design capacity of 96 mAh and a current capacity of 92 mAh. These values are ridiculously low, especially the 96 mAh design capacity given the fact that the capacity advertised on the battery label is 5300 mAh. So I feel that the battery might be ok but it might have some compatibility problem with the bios that results in the wrong acpi values and the consequent shut down of the machine by the OS due to the supposedly very low charge level. Is this possible? If yes, can it be fixed in some way? Or is it more plausible that the battery is simply dead?

Thanks for the help.

ewaller

Administrator

From: Pasadena, CA

Registered: 2009-07-13

Posts: 20,642

Re: Weird battery behavior

The "design" capacity should never change, although the "full" capacity will deteriorate over the life of the battery.
Two things you might try.  Does the Pre-boot menu (sometimes mistakenly called the BIOS menu on uEFI machines) have any kind of battery calibration functionality?  If so, try that.
You might also remove all power sources from the laptop for several minutes (the battery and the external supply), reconnect the battery and external supply, and see if the situation improves.

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snack

Member

From: Italy

Registered: 2009-01-13

Posts: 893

Re: Weird battery behavior

The pre-boot menu has no option for battery calibration (quite an old machine, I think with a "real  BIOS"). To see if the problem was a dead battery or a mistake in ACPI reads I disabled the automatic suspend on low battery and let the  battery deplete completely. It sat at 0% for about half a hour before shutting down, so it was a problem of bad ACPI reads. Interestingly, after recharging the battery the estimated duration was about 30 min instead of just 2 as before, as if the forced full power cycle somehow did a battery reset. Effectively, after doing it I found some posts suggesting this procedure to re-calibrate a battery. The readings seem fine now, and the battery level goes down smoothly as it depletes (before it went down with 33% steps), so I'd say that the problem is fixed.

Last edited by snack (2020-10-05 07:01:07)