How to get the correct battery status?

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?

Here is Solutions:

We have many solutions to this problem, But we recommend you to use the first solution because it is tested & true solution that will 100% work for you.

Solution 1

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.

Solution 2

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!

Note: Use and implement solution 1 because this method fully tested our system.
Thank you 🙂

All methods was sourced from or, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

Leave a Reply