UPS woes
December 5, 2005 12:30 PM   Subscribe

I have two UPS boxes (APC CS 500 and APC ES 500). Both have this issue: I have two machines plugged into it. I shut the power off. What's supposed to happen is that the UPS is supposed to power the boxes for X number of minutes on its battery, but what actually happens is both machines shut right down in that second when the thing(s) go(es) to battery. Any ideas why? Isn't that... wrong?
posted by xmutex to Computers & Internet (24 answers total)
 
How are the UPSes connected to the computers, data-wise? Serial? USB? It sounds like the computer is not getting the notification you're on battery, or is not configured in software to wait X minutes. Are you using the APS driver, or something else?
posted by Triode at 12:35 PM on December 5, 2005


Oh, the computers are just plugged into the UPS for power. I haven't connected anything for the data, but I don't think that would be required just to have the computers keep running when the unit switches to battery. Am I wrong?
posted by xmutex at 12:36 PM on December 5, 2005


Two computers? Are you sure you're not overloading the poor thing?
posted by cillit bang at 12:39 PM on December 5, 2005


Reading the spec on one of those seems to imply that the maximum output is 500 watts. The combined draw of the two computers is probably over that. What kind of computers are they? Is the monitor feeding off the UPS as well?
posted by justkevin at 12:44 PM on December 5, 2005


The idea of a UPS is that you get notified and have time to do a graceful shutdown. The computers need a data link to the UPS to be able to know when they are on battery. Otherwise, when the battery runs out, it's just like the cord has been yanked. It's usually a serial cable, newer UPSes use USB. The computer also needs a driver to talk to the UPS. APC provides one, but Windows XP has one built in, it's in the Power control panel.

And a 500 VA UPS is small for running the machines for very long at all - an immediate graceful shutdown may be all you get.
posted by Triode at 12:46 PM on December 5, 2005


I determined that a 500VA APC UPS is insufficient to power a dual Power Macintosh G5 for any length of time. Two regular computers would probably be tough too. Get a bigger one. Ideally, find yourself a 1000+VA SmartUPS (sine wave, line-interactive) on eBay with dead batteries and buy new ones for it.
posted by kindall at 12:49 PM on December 5, 2005


I believe the question states each machine is connected to a UPS, not that both are connected to one particular UPS. Is that right?

On preview, Triode, while that is "nice to have", UPSs do not operate this way - when the power goes out they are supposed to step in within a frame of time small enough to prevent the computer from turning off, regardless of notification or automatic action the computer takes upon notification. The whole point of the "U" part of the UPS is to give the user some minutes to save the data and turn off the computer manually.
posted by nkyad at 12:53 PM on December 5, 2005


xmutex, I was about to tell you to RTFM, but then I went and did so... I may have mislead you. It appear the CS series does not seem to connect to the computer.. so it cannot tell the computer to do a graceful down. Not really a UPS, IMO. strange product design.

On the ES, the data port is the bottom-most RJ45 jack. (Again, way to go with using a non-unique connector, product designers, that'll never confuse the consumer) You should have a cord that's RJ45 (ethernet-ish) to USB. Use that to plug the ups into the computer.

on preview- Yeah, i just learned that, nykad. In my opinion that thing should be used to hold doors open, or maybe to prevent papers blowing away in the wind. Anything worth plugging a PC into should be able to gracefully shutdown the computer. APC is engineering to a price, not a product. Yuck.
posted by Triode at 1:01 PM on December 5, 2005


Sounds like you're either putting too much load on the UPS, or the batteries are gone/dead.

Try plugging one system into each UPS (instead of both into the same UPS) and see if the same thing happens. If not, you're overloading a single UPS.
posted by mrbill at 1:36 PM on December 5, 2005



I determined that a 500VA APC UPS is insufficient to power a dual Power Macintosh G5 for any length of time.


Well that's interesting. I have a dual G5 (2.3ghz) and a little Shuttle XPC machine running Windows 2003 plugged into the battety-backed-up outlets. Everything else (monitor, etc) is plugged into the surge-protected outlets. Instantly they both shut down the power goes out.
posted by xmutex at 1:38 PM on December 5, 2005


Most APC UPSs have two sets of outlets. Some of the outlets are battery backed, the others are merely surge protected. Are you sure you have the computers plugged into the battery backed outlets?

As for the idea that a UPS MUST include a provision for signalling a PC to allow for graceful shutdown, I think there are lots of situations where such a feature is merely nice to have, rather than must have.

We bought cheap UPSs for all our desktop users at one point because I realized that just being able to float a PC for 60 seconds during a transient power glitch would probably cut the data/productivity loss from power problems by ~90% because most outages were really brief.
posted by Good Brain at 1:46 PM on December 5, 2005


Some UPS's ship with the batteries disconnected. I know this sounds obvious, but have you checked that the batteries are connected? (I've run into this multiple times over the years while helping out friends and family.)
posted by Svenny at 1:46 PM on December 5, 2005


I run two recent vintage PCs, an LCD. and a stack of home office grade network hardware off a single ES 500. It's enough to last about 120 seconds when the power goes out, which is about 115 seconds longer than I need. I'm way out of spec but it still works. Try your UPS with something very small plugged into it and then keep stepping up until it stops working.

The data cable has nothing at all to do with it. Nice to have that working too, may even help you debug the problem, but it's not causing it.
posted by Nelson at 1:52 PM on December 5, 2005


when the power goes, does the ups start beeping, or does it go dead? if it happily beaps away then there's a problem in the transition (are you sure you're plugged into the batter supported sockets - some machines have additional sockets that are filtered only; not all the sockets have battery backup). if it doesn't beep, and all lights are off, then there's a problem with the battery (eg it's not connected).
posted by andrew cooke at 2:03 PM on December 5, 2005


andrew: The battery is definitely connected, the machines are definitely plugged into the battery'ed outlets, and the UPS boxes go beep beep beep when the power gets shut down. The UPS doesn't seem to miss a beat, but the G5 and the Windows 2003 machine go off instantly. I figured I'd get minimal up time on the battery w/ a G5 and a Windows box, but I figured they'd at least last 30 seconds (just long enough to halt/shutdown).

My power is strange, so sometimes I get... I don't know what you call them... power snaps, where it'll blink off for a split second, and it is these instances that I am trying to keep the machines powered on through.

I am guessing, though, that maybe these two machines are too much for either the ES 500 or the CS 500.
posted by xmutex at 2:09 PM on December 5, 2005


When you say you shut the power off, do you mean with a switch on the UPS? If so, that's what's supposed to happen. A better test is to use the test button, or unplug the UPS from the mains.

Are these new? If not, the batteries might not be able to hold a charge. Replacing the batteries might be a possibility if these UPS's were designed for that (and if you are capable of changing a car battery).
posted by kc0dxh at 2:10 PM on December 5, 2005


kc0dxh: By shutting the power off, I mean I unplig the UPS from the wall.

These are new. Brand new. I bought the ES 500 on Saturday.
posted by xmutex at 2:15 PM on December 5, 2005


Try plugging in a lamp only and see if the UPS can keep that powered up. If not, you may have a defective unit. I know it sounds incredible to have two defective units purchased at the same time. Stranger things have happened.

Cool having someone answer a reply question right away...
posted by kc0dxh at 2:22 PM on December 5, 2005


The suggestion has already been made above, but you really should open the battery compartments and make sure the batteries are connected. Most UPS units (including every APC product I've ever owned) ship new with the batteries disconnected at the hot side, to keep them from discharging during shipping and pre-sale storage. Not connected = no protection, but they fire up and look like they are working, as even a UPS with dead batteries can supply line filtering and over-voltage protection services.

Just slip on the hot side battery terminal connection, charge the units for several hours, before connecting loads, and you'll probably be good to go.
posted by paulsc at 4:42 PM on December 5, 2005


but what actually happens is both machines shut right down in that second when the thing(s) go(es) to battery. Any ideas why? Isn't that... wrong?

Only in nomenclature. It sounds from your description like what you actually have then are standby power supplies -- they run your computers off of AC from the wall, and then switch to battery if the wall cuts out. The trouble is, there is a "standby" time, which creates basically a brownout for your computer. Your PCs are sensitive enough to notice the brownout and shut down (or reboot -- you can usually set behavior after power failure in the BIOS).

True UPSes would run your computer off the batteries at all times, and keep recharging the batteries from the wall. If the AC cuts out, there is no "switch time," only that the UPS battery doesn't charge anymore. These are nice, but the batteries have to be replaced more frequently.

Oddly enough, the APC website doesn't tell you what the switch time is, so maybe there's another explanation...
posted by NucleophilicAttack at 5:06 PM on December 5, 2005


Oddly enough, the APC website doesn't tell you what the switch time is, so maybe there's another explanation...

It's probably too awful to publish.

True UPSes would run your computer off the batteries at all times, and keep recharging the batteries from the wall.

These are also called online UPSes, and they have efficiency issues because every bit of electricity that goes through them has to be converted to DC and then converted back to AC, incurring losses each time. Not really intended for a desktop user. More info on UPSes here

Thanks for this thread. I was going to pick up an el-cheapo APC, but now I realize that it's really better to wait until I have enough cash for a better one.
posted by breath at 6:39 PM on December 5, 2005


APC has pretty good customer service in my experience. If you talk to them, they'll probably start by telling you to do what kc0dxh suggests: plug in something small to test whether the UPS is working at all.

That's what they did when I complained that my CS 500 with my shiny new G5 plugged into it was shutting off immediately when the power went out. Turns out that that model is totally inadequate for my power needs.

They've got a web app that'll tell you what models will keep different kinds of computer on for specified periods.
posted by aneel at 9:01 PM on December 5, 2005


That's what they did when I complained that my CS 500 with my shiny new G5 plugged into it was shutting off immediately when the power went out. Turns out that that model is totally inadequate for my power needs.

Yeah, I have a G5 too. I think this inadequacy issue is basically the bottom line here. Damnation.

Thanks all.
posted by xmutex at 10:03 PM on December 5, 2005


Wow, interesting. Many PCs have power supplies that can handle a very short duration drop in power; maybe the G5 is just really tempermental? If so it's not capacity at all, it's switching time.
posted by Nelson at 3:52 PM on December 6, 2005


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