# Solved: pc shuts down while on ups battery



## mtf (May 17, 2003)

My PC shuts down and restarts while connected to 1000 VA UPS backup battery. PC Power: 475 Watts -- Do I need a higher capacity UPS? Please help!Thank you.


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## cwwozniak (Nov 29, 2005)

Does it happen only when running from battery power and/or when AC power if feeding the UPS?

Is the UPS running anything besides the PC?

Does the computer have some kind of data cable connection to the UPS and is the computer running software to check the UPS status?

How long has the UPS been in use?


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## mtf (May 17, 2003)

Does it happen only when running from battery power and/or when AC power if feeding the UPS? It happens when utility company power goes off. A message appears like "going to power save mode" and reboots -- when it does, black Windows prompts you to start as usual or safe mode, etc. I have an emergency power generator that powers up the entire house with automatic transfer switch when power fails. Had no problem the last 10 years with other PCs connected to UPS.


Is the UPS running anything besides the PC? The PC and the monitor.


Does the computer have some kind of data cable connection to the UPS and is the computer running software to check the UPS status? No


How long has the UPS been in use? About 2 mos.


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## cwwozniak (Nov 29, 2005)

Dumb question but I have to ask ...

Some UPS units have some AC outlets that have battery backup and surge suppression while other outlets only have surge suppression but no battery backup. Are you 100% sure the computer is plugged into a battery backed outlet on the UPS?


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## mtf (May 17, 2003)

Yes, it has 8 protected outlets, 4 of those battery-backup. Yes, the computer is plugged into battery-backed outlet. The UPS also has automatic voltage regulation. Additionally, I plugged in a different PC, turned off the breaker, and the PC kept working without a hitch -- as if nothing had happened. I also turned on the other computer using only the UPS battery; also tested a lamp. But my new PC won't turn on and won't stay on when power fails. Very strange.


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## cwwozniak (Nov 29, 2005)

Yes that is very strange.

This is a pure wild guess on my part. Some UPS equipment does not come close to generating a nice sine wave AC output but instead uses a series of stepped levels that kind of approximate a sine wave. It may be possible that the power supply in the computer can not work properly with the voltage wave form out of the UPS when running on batteries.


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## w_tom (Nov 29, 2008)

mtf said:


> I also turned on the other computer using only the UPS battery; also tested a lamp. But my new PC won't turn on and won't stay on when power fails.


New PC? Does this new PC have power factor correction?

UPS power in battery backup mode is some of the dirtiest power in the building. Power so 'dirty' that it can confuse power factor correction circuits. 

For cleanest power, a UPS connects the computer directly to AC mains. When it switches to battery backup mode, that power is so 'dirty' as to be harmful to power strip protectors and small electric motors. And 'dirty' UPS power is ideal power for all electronics - because electronics are required to be more robust.

Because they are often sold on hearsay, a UPS will claim some kind of pure sine wave. Well, all 'dirty' electricity is a mathematical sum of pure sine waves. They don't lie. They just let you beleive spin.

'Dirty' UPS power can confuse a new computer's PFC circuits - cause a shutdown. Does that new computer have PFC? Only place to know is its numeric specifications.


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## BubbaLicious (Jul 20, 2010)

mtf said:


> My PC shuts down and restarts while connected to 1000 VA UPS backup battery. PC Power: 475 Watts -- Do I need a higher capacity UPS? Please help!Thank you.


As some of the other users here stated it could be that you are using an active PFC power supply with a UPS that doesn't produce a sine wave. If that's the case, when the UPS is operating from utility power then the power passes through the UPS like a power bar, when the power fails the unit switches to batteries and provides your unit with a stepped/square wave which causes your computer to restart. This could be the case if you are using a unit like the Smart-UPS SC 1000 which is a 1000VA unit, 600W, 6 protected outlets and outputs a stepped approximation.

If you are using a unit like the APC Smart-UPS 1000VA LCD which has 1000VA, 670W, 8 protected outlets and a sine wave output, then you should not be having a problem of this kind. The line interactive units are generator compatible and output a sine wave output. This kind of unit should not be restarting your PC.

Have you switched comm cables on the UPS? Can you give us an exact model number of the UPS? What kind of PC do you have? If you provide this info it would be much easier to figure it out.


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## BubbaLicious (Jul 20, 2010)

w_tom said:


> New PC? Does this new PC have power factor correction?
> 
> UPS power in battery backup mode is some of the dirtiest power in the building. Power so 'dirty' that it can confuse power factor correction circuits.
> 
> ...


Hey,

Can you provide us your full specifications on the UPS and the PC? What's the brand, what kind of PSU and any other info would be appreciated.


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## mtf (May 17, 2003)

Dell Studio XPS Desktop 9000 - 64-bit Windows 7 Home Premium - Intel Core i7 CPU - 8 GB RAM 

Computer/Home Theater Battery Backup w/surge protection, noise filtering and automatic voltage regulation.
Tripp-Lite G1000UB - Capacity (Volt-Amps/Watts) 1000 VA/500 W; AC Output 120V/60Hz; Outlets 8 with surge protection; 4 of these battery backup.

This unit number is not listed in Tripp-Lite support site except that it is sold by a "partner". In this case, Costco.

Thanks for your help!


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## BubbaLicious (Jul 20, 2010)

mtf said:


> Dell Studio XPS Desktop 9000 - 64-bit Windows 7 Home Premium - Intel Core i7 CPU - 8 GB RAM
> 
> Computer/Home Theater Battery Backup w/surge protection, noise filtering and automatic voltage regulation.
> Tripp-Lite G1000UB - Capacity (Volt-Amps/Watts) 1000 VA/500 W; AC Output 120V/60Hz; Outlets 8 with surge protection; 4 of these battery backup.
> ...


Thanks for the info, now it's much clearer. The reason you're having system failures with this unit is as I suspected. The Tripp-Lite G1000UB outputs a modified sine wave (PWM) which is incompatible with active PFC power supplies, especially like the one used in the XPS 9000. The Tripp-Lite unit is a great little unit but it can only be used for an older desktop PC which has an older style power supply which isn't affected by the modified wave.

The XPS 9000 has a power supply rated at 475W, so at a minimum you need something like the Smart-UPS 1000 SUA1000 which has 670W to sustain the system. The SUA1000 is a line interactive unit which outputs a sine wave, offer AVR boost/drop and power filtering surge protection capability. It's a data center unit usually used on servers and high end machines. The Smart-UPS series is compatible with generators. On the SUA1000 at 475W you'd have an approximate run time of 10 minutes. Definitely more than enough to shut down safely. You can also plug in your modem/router to protect them as well.

There are other options as well to provide longer run time and higher capacity, but it's all based on your budget and needs. I would recommend putting the TrippLite on another PC where you know it works well with you and get yourself a Smart-UPS for the XPS 9000.


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## mtf (May 17, 2003)

Thank you for your help. I'll do just that. Take care!


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