I have an ASUS N550JK laptop (BIOS version 204) running Ubuntu 14.04 (3.13.0-43-generic kernel).

My issue is that the battery indicator ALWAYS shows that it's using battery power - even when plugged in and fully charged. So even though I have selected to show the battery status in the menu bar only when charging or in use (in power settings), it is ALWAYS displayed. When it reaches a full charge, the indicator icon will either show just the percentage (usually 99% or 100%), or sometimes a very big number for time (like 22:14) along with the percentage. If I go to the power settings menu, it always says "Using battery power", with something like 40 hours remaining. This is all while plugged in and fully charged.

Are there any fixes less drastic than trying to update BIOS, or is a BIOS update necessary to fix this? The latest BIOS version is 208 according to the ASUS website, but the (very brief) descriptions of the updates don't mention anything about battery issues. If at all possible I'd like to avoid updating BIOS because of the risk involved.

I've already tried letting the battery drain all the way and then charging to full, with no luck.

Thanks in advance!

  • I have the same issue on Asus K551LN. It seems to be a linux firmware related problem because when I boot windows 8.1 (I have a dual boot) the power/battery indicator works correctly.
    – MartinH
    Feb 21, 2015 at 20:32
  • You should update on Kernel 3.16. Maybe a new Kernel will fix your problem. If you dont know how to do this follow these steps: ubuntuforums.org/showthread.php?t=2266369. Remember that the new kernel will just be supported until the next LTS version.
    – MofaSofa
    Mar 4, 2015 at 11:22
  • I have this laptop, but on BIOS version 208. I am dual booting 15.04 and Yosemite 10.10.3. I had the same problem under OS X, but was able to patch my DSDT to correct the problem. I am trying to compile the DSDT for Linux, but getting errors. I will keep trying.
    – user420996
    Jun 17, 2015 at 12:12

3 Answers 3


I would turn the laptop off and take out the battery and plug it in to see if it thinks it is on battery power that should make work I think.


It seem there is a bug in the acpi, this could be corrected with a modded DSDT but i don't know how to make it load in Ubuntu (tried and failed on my N551JM) here is what user Vmonheros write about it:

The culprit is here, inside method FBST (called inside _BST)

Store (Zero, Local0)
If (^^LPCB.EC0.ACAP ())
Store (One, Local0)

So Local0=1 if the laptop is on power, fine ;)

If (Local0)
If (CHGS (Zero)) here CHGS =0 id battery is charging
Store (0x02, Local0)
Store (One, Local0) The error is here, if I'm on power and battery is not charging, we must store zero, not one !
Store (One, Local0) }

With this "small" correction, everything works well now.


More discussion of similar problem here:


For me removing the power supply did not affect the battery state (was still "discharging"), however it was detecting the presence of the power cable (as cat /sys/class/power_supply/AC0/online returns 1).

The instructions below from aceat64 at link above fixed it:

  1. Unplug the laptop
  2. Hold power button until the laptop powers down
  3. Plug in the power cord, the connector should stay amber. If it flashes amber/green it's not charging.

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