[ltp] Re: Re: Power drain with ACPI

[Joel Ebel]

I have figured out the cause for my power drain.  This only affects 
Windows.  I don't use ACPI in Linux, and APM sleep has always worked 
fine.  I don't know if this will help those who are experiencing a 
similar problem in Linux or not, but here's what I found out.  Starting 
with BIOS 3.06f for my T40, a feature was added to prevent the computer 
from waking up from sleep on a timer.  This was done to prevent the hard 
drive from operating while the computer wasn't stationary.  However, 
apparently, when the computer tries to wake up from standby to go into 
hibernation, it begins to use more power, and it never shuts off.  There 
are two solutions I found to this problem.

1.  Make sure the OS isn't set to wake up from standby in order to go 
into hibernation.
2.  Enable the option in the BIOS to allow the computer to wake up from 
standby with a timer.

Either of these seems to work fine for me in Windows.  Hopefully they 
will help in the search for the solution for Linux.

Joel Ebel

Volker Braun wrote:
> I always suspend for about an hour to test, and then calculate the drain
> from ACPI battery status. I always get around 5W, which is about right
> compared to the battery loss on longer suspends. 
> 
> Using an ampmeter may work, have not tried that yet. Don't electrocute
> yourself by playing with mains :-)
> 
> I have not tried the XP suspend since SP2, will try later. If anything
> changed I'll let you know.
> 
> Best,
> Volker
> 
>