BACK-UPS RS 900G keeps waking up my PC?

[Anonymous user]

I had my new PC plugged into the UPS for a while and everything was fine.  Yesterday I had a power cut and the PC switched off (not gracefully)after about 3-4 seconds.  I realised that the USB cable wasn't connected and I hadn't got around to installing the software yet - would either of those explain why the PC switched off?  I would have thought that it would have just continued supplying power regardless of software/usb?  Or is it more likely that my battery is just knackered? (and how do I check the battery?)

Anyway, after that happened I connected the USB cable and installed PowerChute Personal 3.0.2

However, now whenever I put the PC into hibernate mode (which I do all the time due to the number of apps I have open) the PC just switches itself back on a few seconds after it hibernates.

Is that some function of the software?  Can it be switched off?

[Anonymous user]

Up until the UPS actually runs out of battery power, it won't matter if the USB cable is connected or not. The UPS will operate as normal, for as long as it can.

You can check the battery in a few ways. The first would be to place a non-essential load on the UPS (something that won't mind a sudden shut down if the battery is bad, and that's close to the load normally supported by the UPS). Incandescent light bulbs work great for this, but if you can't get any of those, powering up your computer and leaving it at something like the BIOS setup screen will also do. Either way, unplug the UPS from the wall outlet and see what it does. If it shuts off immediately, or within a few seconds, you can be pretty sure the batteries are bad. The UPS will also emit a long tone when the batteries become exhausted and the load is shut down, unless you've muted it.

APC's supplied batteries and battery packs all have a sticker on them somewhere with a serial number. After any letters at the beginning of the serial number, the next four digits are the date code in year/week format. A battery that's any more than three years old is suspect. Third party batteries (and even many that are packaged by APC) will also have a date code stamped somewhere in the battery's body. However, its format may vary.

I'm not sure about the hibernation issue. I could only suggest disconnecting the UPS from the PC to see if its behavior changes. You might also want to check the power on settings in the system BIOS. They might have been scrambled in some way by the sudden power down. PowerChute shouldn't affect the system's ability to hibernate.

You may also want to reset the UPS. This can be done by safely powering down your attached load, turning the UPS off, unplugging it from the wall and removing the battery. After doing all that, press and hold the UPS's power button for a few seconds. Don't be surprised if it reacts briefly. Reconnect the battery, restore power, and reconnect your load as necessary.

[Anonymous user · Accepted solution]

I uninstalled powerchute yesterday and it made no difference to the hibernation problem.  But then I removed the USB link to the UPS and that fixed it.

So, for whatever reason, the UPS itself keeps waking the PC up from hibernation, not the software.

I think the UPS is more than 3-4 years old, so it's probably the battery that caused the shutdown, I'll test it when I get time.

[lmstearn_apc]

Thanks for the heads up, on one rig it usually happens with hibernation, a newer PC happens after shutdown as well, see related.

The newer rig restarts from hibernation when it is not connected to either the UPS, or UPS USB port, or both. Could be an overly enthusiastic power supply as well.

Edit: A newer rig had the issue only with hibernation. This answer regarding turning off Wake-on Lan may help some, otherwise turning off wake for all USB Hid keyboards and USB Hid mice as explained here helps as well.