# Battery Back-Up



## maddy (Oct 30, 2010)

I recently got an APC battery back-up/surge protector for power outages. When the power goes out, the unit begins beeping, which gives me just enough time to shut the computer down properly. After shutting down the computer, however, the unit continues to beep until you either turn the unit off or unplug it.

It concerned me to turn the unit off because I was afraid that I'd lose the benefit of the surge protector when the power came back on. Unfortunately the owner's manual is designed for 20-somethings who already know all this, so it doesn't address the issue.

Does anyone happen to know whether the surge protector part of the unit works even when the unit is turned off? If not, how do you get the darned thing to stop beeping without turning it off?

Many thanks in advance. ~Maddy


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## DaveNay (Nov 25, 2012)

When you press the switch to turn the device off, you are disconnecting from the wall outlet completely. There is an "air-gap" and therefore you should be immune from 99% of surges. Obviously something as potent as a direct lightning strike can still fry your equipment, but that is true even if the surge suppressor is turned on.


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## Harry Chickpea (Dec 19, 2008)

Without tearing it apart or examining a schematic, I can't say for sure but the surge protection SHOULD remain. Basic surge protection is pretty simple stuff and would logically be ahead of the back-up power circuitry.


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## simi-steading (Sep 27, 2012)

Um.. If you have to physically shut off the UPS to get it to stop beeping, why not just unplug the computer or the UPS after you shut it off anyway?

That way there is no question of any way of any kind of surge doing any damage.. 

Sorry I'm sounding like Mr. Obvious here...


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## simi-steading (Sep 27, 2012)

Oh.. as far as the alarm.. some units do have an alarm silence... You need to read the manual.. 

Also, some UPS units will only beep if the batteries are going bad... You really need to RTM..


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## Darren (May 10, 2002)

DaveNay said:


> When you press the switch to turn the device off, you are disconnecting from the wall outlet completely. There is an "air-gap" and therefore you should be immune from 99% of surges. Obviously *something as potent as a direct lightning strike can still fry your equipment*, but that is true even if the surge suppressor is turned on.


Not necessarily. One brand, Clary, did stop a lightening strike that destroyed everything else connected to a wall outlet in a house. The computers connected to the UPS were unscathed. Clary doesn't sell to the retail market. Their units are marketed for critical use situations. They show up on ebay occasionally.


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## Nevada (Sep 9, 2004)

As I understand it, surge suppressors use a condenser to absorb excess current during a power surge, then slowly discharge after the power surge has ended. The surge suppressor can also help during a lower power moment. Surge suppressors are not intended for lightning protection, only minor power fluctuations.

There is no reason to believe that the surge suppressor capability isn't working when the UPS unit isn't powered. After all, the condenser is still in the circuit.


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## Darren (May 10, 2002)

I'm not sure about all UPS units. The ones built by Clary generate AC current from the batteries. The connected devices never see outlet power. The smallest Clary units look like rural mailboxes.


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## DaveNay (Nov 25, 2012)

Darren said:


> I'm not sure about all UPS units. The ones built by Clary generate AC current from the batteries. The connected devices never see outlet power. The smallest Clary units look like rural mailboxes.


The vast majority of consumer devices do not work this way.

http://www.techvigil.com/electronics/116/Difference-Between-Offline-and-Online-UPS/


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## Harry Chickpea (Dec 19, 2008)

Condensers are used to smooth very minor low amperage "glitches" in power, such as the induced voltage from a nearby source of sparking or a motor that backfeeds spikes into the line. The key is LOW amperage. That size capacitor doesn't stand up to high amp abuse. Most of the time it will "clean" the sine wave a little, but if a big surge comes along, the device that handles it is a MOV (metal oxide varisistor) In a large surge, even these will blow, while giving that one-time protection. Many consumer grade surge protectors have a protection light to indicate if the MOV is blown and no longer functional. Even better is a combination of the above with toroidal coils, which "choke" the spike by causing the EMF to act against itself.

There are various classes of surge protection that give trade-offs. Most consumer grade UPS/surge protection is line-interactive.


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