Secondary battery problems with 2.6.8 kernel - Portable

This is a discussion on Secondary battery problems with 2.6.8 kernel - Portable ; Hi, I have an Alienware Sentia-M system, running SuSe 9.1 Linux but with the SuSe 9.2 kernel (2.6.8-24.11-default), that has a secondary battery which is not working. The output of 'cat /proc/acpi/battery/BAT1/state' shows: present: yes capacity state: ok charging state: ...

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Thread: Secondary battery problems with 2.6.8 kernel

  1. Secondary battery problems with 2.6.8 kernel

    Hi,

    I have an Alienware Sentia-M system, running SuSe 9.1 Linux but with
    the SuSe 9.2 kernel (2.6.8-24.11-default), that has a secondary battery
    which is not working. The output of 'cat
    /proc/acpi/battery/BAT1/state' shows:

    present: yes
    capacity state: ok
    charging state: charged
    present rate: 2255 mW
    remaining capacity: 2899 mWh
    present voltage: 0 mV

    But the 'present voltage' is never anything other that '0 mV'. Because
    of this I actually see a drop in the time remaining when I am running
    the laptop off batteries! When I was running Windows XP I used to see
    an increased time I could use the laptop for on batteries but Linux
    shutdowns something like 10-15 minutes before the primary battery runs
    out, rather than turning on the secondary battery (if that's what it's
    supposed to do).

    Does anyone know whether this is a (AMI) BIOS problem or something
    within the kernel?

    Matt


  2. Re: Secondary battery problems with 2.6.8 kernel


    > I have an Alienware Sentia-M system, running SuSe 9.1 Linux but with
    > the SuSe 9.2 kernel (2.6.8-24.11-default), that has a secondary

    battery
    > which is not working. The output of 'cat


    A little test to try: Take out both batteries and remove AC power.
    Insert just the secondary battery. See if you can power up the laptop.


  3. Re: Secondary battery problems with 2.6.8 kernel

    Ok, I took out the primary battery and booted up the laptop using the
    secondary battery. The output of 'cat /proc/acpi/battery/BAT0/state'
    (the primary) is:

    present: no

    The output of 'cat /proc/acpi/battery/BAT1/state' (the secondary) is:

    present: yes
    capacity state: ok
    charging state: discharging
    present rate: 2255 mW
    remaining capacity: 2825 mWh
    present voltage: 0 mV

    So the 'present voltage' is still at 0mV but the laptop is certainly up
    and running!

    So I plugged back in the primary battery and that simply changed the
    'charging state' of BAT1 to 'charged' and the output of 'cat
    /proc/acpi/battery/BAT0/state' as:

    present: yes
    capacity state: ok
    charging state: discharging
    present rate: 1231 mW
    remaining capacity: 3189 mWh
    present voltage: 16254 mV

    So, I guess that Linux is being fooled into thinking that once the
    primary battery is out of juice that the secondary battery can't help
    (because of the 0mV 'present voltage'). How would I work around that
    and does this make it clearer as to whether this is a BIOS or kernel
    issue?

    Matt


  4. Re: Secondary battery problems with 2.6.8 kernel

    > So the 'present voltage' is still at 0mV but the laptop is certainly
    up
    > and running!


    Sounds like a BIOS bug to me. Do you have Windows installed on this
    laptop? I'd be curious to see if Windows can report the battery state
    accurately.


  5. Re: Secondary battery problems with 2.6.8 kernel

    On 2005-01-31, larwe@larwe.com wrote:
    >> So the 'present voltage' is still at 0mV but the laptop is certainly

    > up
    >> and running!

    >
    > Sounds like a BIOS bug to me. Do you have Windows installed on this
    > laptop? I'd be curious to see if Windows can report the battery state
    > accurately.
    >

    Not a BIOS bug but a ACPI DSDT bug (which is acquired from the BIOS, so kind
    of right You can learn more about this by going to
    http://acpi.sourceforge.net/ (IIRC) or sending me the output from:

    # cat /prox/acpi/dsdt > DSDT.aml

    I will then rewrite the relevant section for you after you install the
    'acpi initrd' patch. then things should start working. On my Thinkpad T40p
    I had plenty of ACPI DSDT 'bugs'. I have managed to enable fan support,
    found five additional sensors, enabled C4 power saving, enable support to
    change the LCD brightness through ACPI and add 'linux' support flags to the
    table. You can have a lot of fun with it and make you machine much more
    power saving friendly, if you have the time.

    Cheers

    Alex

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