Uninterruptible power supply follies
Last night around 2:10 am, my two APC Smart-UPS 1000XL uninterruptible power supplies switched onto their batteries as the power failed, and began to beep loudly 4 times each minute. This might be fine for a room full of servers, but it’s hardly friendly stuff for a home. Fortunately, there is an option to disable the beeping completely—and though the fans are far from whisper-quiet, they are not annoying in pitch. I discovered a few interesting things, which I’ll share here.
First, it’s no fun figuring out how to disable the beeping at 2am. It’s better to do so at a more civilized hour.
Second, and perhaps taking a design award for untempered stupidity, if you turn off the Smart-UPS 1000XL, and there is no line current, you cannot turn it back on! One has to wonder at what the “Dumb-UPS 1000” did—require sending it in for service? No need to believe me—read the manual. Any attempt to turn on the unit without line current just results in a short beep. I had turned off one unit because it was for equipment I wasn’t using, and even “off” that equipment was sucking 10-20 watts (“vampire devices”). I didn’t want to drain the batteries needlessly, so off it went (the other 1000XL continuing to power my server). Then I realized that I needed some information from the APC web site on how to disable the beeping, but there was a problem: the unit I had turned off would not turn back on (no line current). Brilliant design. There’s even a troubleshooting section in the manual describing the possible reasons the unit won’t turn on—including no line current. Isn’t this a battery-powered UPS? Fortunately, the server-dedicated 1000XL was still on, so I plugged the “off” unit into the “on” unit, powered on the “off” unit, and I was up and running. I haven’t yet called APS support to delve into this.
Next up was disabling the beeping. The provided CD has three programs on it—but just try to figure out which one you must install in order to “talk” to the UPS to disable the beeping. The trick is to install all three, then poke around; the beep setting is cleverly hidden, but can be found, assuming you notice the tiny “Advanced” checkbox, which then makes additional settings appear (including the beeping thing). I didn’t know it was “advanced” usage to abhor annoying beeps. Apparently there is a “personal use” version, but APC wasn’t thoughtful enough to put that on the CD; perhaps they didn’t want to use up the other 600 unused megabytes on the CD. But I digress...
You can’t use an ordinary serial cable to “talk” to the UPS; you must use the APC-provided one. This is fine, except that it’s about 6 feet long, and if your UPS is 12 feet away, it means you have to power off the UPS (see earlier discussion), disconnect any additional batteries, risk a hernia moving it next to the computer (60 pounds, and sorry, no Macs, only PCs), connect the serial cable, puzzle through the software (see above), then triumphantly disable the beep, power the unit down, reconnect and recable it, then power up whatever was originally connected to it. Wait!—it won’t start without line current, so get a 12-foot extension cord, plug it into the “on” unit, and power up the “off” unit. Whew! Really fun stuff at 3am. APC also provides a USB cable, but I was not successful using it, and it too is only about 6 feet long. Now repeat the process for the 2nd unit, but discover that the software is unhappy that you unplugged the cable and plugged it into a different unit. So quit the software and start it again.
Enough grumbling, these units work great, right? Yes and no. The equipment connected to the 1000XL ran flawlessly. However, within a few minutes of power failure, a load of about 30-40 watts already had drawn down one unit from 5 lights to 4 (according to the charge lights on the 1000XL), and this is with an extra battery (the Smart-UPS XL 24V Battery Pack) attached to the 1000XL (manufacture date 11/06). In theory, a Smart-UPS 1000XL and an extra battery pack should be able to power a 35 watt load for 23 hours or so (APC web site claims 16:13 for a 50 watt load). I am now very skeptical, and will have to test that theory soon. The fans are noisy enough that they sound like they might eat 20 watts all on their own. Which brings me to the topic of fans, really stupid energy-eating fans—a 35 watt load shouldn’t require activating a powerful fan—surely a temperature-sensitive fan could have been engineered (incidentally the 1000XL was not even warm to the touch).
All’s well that ends well—line current was restored about two hours after failing, and I got some sleep, though the 1000XL fans (both units) continued to run loudly until fully charged. And my server never went down due to power failure (though I did have to take it down while I disabled the beeping, because I had to move the 1000XL next to the PC, due to the 6-foot serial cable).
