I've got a Windows 7 desktop system with an APC UPS to provide backup power during power outages. I've got the UPS connected to the system with a USB cable so that the built-in Windows power utility can monitor the power level, and it's set up to hibernate the system when the battery level gets too low during an extended outage. The system powers down just fine, but when the power is restored to the UPS, the system stays off. How can I get it to turn back on?
Please note that I've already set the Power Management features of the BIOS to "Always On." I imagine the reason it doesn't power back on is because it had a clean shutdown.
For the record, I've tried the APC PowerChute Personal Edition software, which does make it automatically power back on, but it's got a pretty serious bug that keeps it from shutting down the system if someone is logged in remotely.
If at all possible, I'd like to do this without any additional software, but that's probably a long-shot.
[UPDATE] It appears that the way the APC software gets the system to turn back on is by having the UPS turn off the power to the outlets after the system shuts down, and then turning it back on when main power is restored. It does this by sending the UPS a message to turn off the power to the outlets 2 minutes after it starts shutting down the system – long enough to power down most systems. It seems that neither the built-in Windows Power Management or the apcupsd software I tested can perform this function, at least on the test system I've been using.
Best Answer
Apcupsd does do what you want. Our power here is really bad. In the event of a power failure, my system stays on battery for 2 minutes (my choice) in case it is a short duration. After being on battery for 2 minutes, Apcupsd tells the UPS to cut the power to the PC. The UPS has a built in delay of 2 minutes. Apcupsd then issues the Windows hibernate command, so Windows hibernates. Two minutes after the UPS was sent the command, it cuts power to the PC. When power is restored (or if it was already) then the UPS again provides power. You are correct - since the BIOS sees this as the power was cut then restored, the BIOS will do what you set it to do.
A clean shutdown using a UPS - if the UPS does not cut the power to the PC, regardless of whether the power is restored or not, your PC will remain shutdown because the BIOS didn't see a power cut/restore. The BIOS has no other choice. If, when your system shut down, the BIOS detected that power was still present, what would you want it to do - power up the machine? Then there'd be no way to shut your system down.
BIOS requires that PC loses and then gets back the power.