Battery Shutdown Signal Delayed Using Windows NT UPS Service

• Microsoft Windows NT Workstation version 3.51
• Microsoft Windows NT Server version 3.51

SYMPTOMS

If your computer runs Windows NT with an uninterruptable power supply (UPS) and the Windows NT UPS service installed and a power failure occurs, the UPS service initiates the Windows NT shutdown. One of the following symptoms occur when the battery shutdown signal is sent to the battery and the battery shuts down and turns off the computer:

• Windows NT shuts down and then restarts or has already rebooted again before the UPS turns off the computer.

  -or-

• Windows NT shuts down just in time when the computer turns off.

  NOTE: This is not a problem.

  -or-

• Windows NT is still in the process of shutting down when the computer turns off.

CAUSE

The length of time the UPS waits before turning off the computer, also called the Shutdown Wait, is hard coded to two minutes.

The UPS service has no way of knowing exactly when the shut down of Windows NT is complete, because the UPS service runs in User Mode.

WORKAROUND

To customize the Shutdown Wait period to your computer, install the fix mentioned below and change your registry as follows:

WARNING: Using Registry Editor incorrectly can cause serious, system-wide problems that may require you to reinstall Windows NT to correct them. Microsoft cannot guarantee that any problems resulting from the use of Registry Editor can be solved. Use this tool at your own risk.

1. Ensure that you have the following three options enabled in Control Panel UPS and that the UPS device has the capability to perform these options:

       - Power Fail Signal
       - Low Battery Signal
       - Remote UPS Shutdown
   

2. Run Registry Editor (REGEDT32.EXE).

3. From the HKEY_LOCAL_MACHINE subtree, go to the following key:

         \SYSTEM\CurrentControlSet\Services\UPS
   

4. From the Edit menu, choose Add Value.

5. Add the following:

         Value Name: ShutdownWait
         Data Type:  REG_DWORD
         Data: <0 to 600 seconds>
   

   NOTE: The default wait time is still two minutes.

6. Choose OK and quit Registry Editor.

7. Shut down and restart Windows NT.

RESOLUTION

This problem has been corrected in the latest Service Pack for Windows NT version 3.51.

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 3.51. This problem was corrected in the latest Windows NT 3.51 U.S. Service Pack. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

   S E R V P A C K