Windows – System connected to UPS goes to sleep short time after power is lost

batterysleepupswindowswindows 7

I have a Win7 x64 system connected to the UPS. The UPS is capable of maintaining the system power for about 30 minutes. After I have connected the UPS, I have verified this by disconnecting the power cord and everything has worked as expected, I was receiving low level battery notifications and the system went off once the battery has reached the critical level. Since then a long time passed. Recently I was experiencing a power loss several times, and each time the computer went to sleep in a very short time.

I can reproduce this easily any time by disconnecting the power cord from the UPS. When I do this, the system correctly shows the battery level and the remaining battery time when I disconnect the cord (the level starts at 100% and the remaining time at 0:32 and gradually goes down). Yet, the system sleeps after a short while without any warning.

I do not have any 3rd party software installed to manage the UPS, I am using default Windows battery handling. My advanced power settings when on battery are as follows:

  • Sleep after: 20 Minutes
  • Critical battery action: Sleep
  • Low battery level: 20%
  • Critical battery level: 10%
  • Low battery notification: On
  • Low battery action: Do nothing
  • Reserve battery level: 7%

When the system sleeps, following entry is shown in the event log:

The system is entering sleep. Sleep Reason: Battery

<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
<System>
  <Provider Name="Microsoft-Windows-Kernel-Power" Guid="{331C3B3A-2005-44C2-AC5E-77220C37D6B4}" /> 
  <EventID>42</EventID> 
  <Version>2</Version> 
  <Level>4</Level> 
  <Task>64</Task> 
  <Opcode>0</Opcode> 
  <Keywords>0x8000000000000004</Keywords> 
  <TimeCreated SystemTime="2012-08-01T06:55:18.358031800Z" /> 
  <EventRecordID>325242</EventRecordID> 
  <Correlation /> 
  <Execution ProcessID="4" ThreadID="48" /> 
  <Channel>System</Channel> 
  <Computer>xxxxx</Computer> 
  <Security /> 
</System>
<EventData>
  <Data Name="TargetState">4</Data> 
  <Data Name="EffectiveState">4</Data> 
  <Data Name="Reason">2</Data> 
  <Data Name="Flags">0</Data> 
  </EventData>
</Event>

I have found a user reporting and solving a similar problem on Microsoft Answers, in his case the cause were broken drivers for Iomega drive. While I have quite a lot of devices connected to the computer, I do not have any Iomage drive.

  • Is there any systematic way how could I troubleshoot this problem or identify which particular device is malfunctioning and causing the computer to sleep?
  • Does some documentation for "Microsoft-Windows-Kernel-Power", which would help me understand the exact source of the event?

Best Answer

I was not able to solve the issue despite of my efforts. I was not even able to get any more information on the "Microsoft-Windows-Kernel-Power" so far.

The best I could do was a workaround: instead of using native Windows battery management I have installed APCUPSD software and I can no longer observer the issue. With this sotware Windows are not aware of the battery, the APCUPSD controls shutdown directly and I have verified it is not doing so prematurely.

I guess using APC provided PowerChute might work as well, but I did not like the sofware much when I installed it, sounds too much cluttered and obtrusive to me.

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