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