Ask Ubuntu is a question and answer site for Ubuntu users and developers. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

At this moment, ever since I installed Ubuntu on this machine, the battery status says: not present.

Looking at this answer, however, I find that /proc/acpi/battery/BAT1/info (sometimes its /proc/acpi/battery/BAT0/info, use tab complete to help) has the following info:

present: yes

design capacity: 4400 mAh

last full capacity: 4400 mAh

battery technology: rechargeable

design voltage: 11100 mV

design capacity warning: 300 mAh

design capacity low: 132 mAh

cycle count: 0

capacity granularity 1: 32 mAh

capacity granularity 2: 32 mAh

model number: BAT1

serial number: 11

battery type: 11

OEM info: 11

In accordance to this answer, I've checked the /proc/acpi/battery/BAT1/state file:

present: yes

capacity state: ok

charging state: charged

present rate: unknown

remaining capacity: unknown

present voltage: 10000 mV

The acpi -b command returns:

Battery 0: Unknown, 0%, rate information unavailable

Any suggestions on getting the battery info updated?

share|improve this question
up vote 7 down vote accepted

The acpi -b error you have reported most probably indicate an ACPI type issue.

ACPI is an open-standard for device and power-management.

Some laptops (most googled that I found were Acer) incorrectly report its battery details to ubuntu. I'm not sure of your laptop type and model - nor its BIOS version.

Sometimes you need to compile your own kernel with a fixed DSDT table.

Sometimes you need to upgrade your BIOS to the very latest offered by your manufacturer.

If you decide on the latter action you should remember that updating the bios of a motherboard or laptop is always a risky operation, because if something goes wrong, the risk of irreparably damaging the hardware is very high.

You will need to follow the instructions for BIOS updates from your manufacturer.

share|improve this answer
Acer Aspire 5745G. Which option is easier? Compiling the kernel or updating the BIOS? – GUI Junkie Feb 9 '12 at 22:19
... updating your BIOS ... what version is your BIOS? I would carefully read the release notes first because BIOS updating, if not done correctly can leave you without a working laptop. – fossfreedom Feb 9 '12 at 22:43
... I found this link - look at the ACPI on that page. That looks like good news! – fossfreedom Feb 9 '12 at 22:44
The BIOS version is v1.11 (sudo dmidecode -s bios-version) – GUI Junkie Feb 9 '12 at 23:33
the latest version on the acer website is v1.19 - I couldnt find any release notes though :( – fossfreedom Feb 9 '12 at 23:41

I was able to solve this problem using fossfreedom's suggestion to update bios. I have an Acer Aspire TimelineX 4820T, running ubuntu 11.10. Here's what I did:

  1. sudo apt-get install unetbootin
  2. inserted blank flashdrive, used diskutil to format it to FAT
  3. downloaded the CORRECT bios update from Acer (I typed in my serial number and used the latest bios update .exe file)
  4. used unetbootin to make the USB bootable with FreeDOS
  5. copied the bios .exe file to the USB drive
  6. restarted and chose option "5" for FreeDos
  7. switched to C: drive and ran the bios executable. (Make sure you have enough power, although this doesn't take very long)
  8. removed USB drive, rebooted into ubuntu and battery problem was solved!

Thanks go to 4zzdawg for instructions on how to update the bios!

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.