Working from home – A UPS to get you through those power blinks

APC-UPS ES 650A good Uninterrupted Power Supply (UPS) can keep your equipment running through short power outages. It is a good idea no matter where you work from, but especially if you work from home. Here’s why:

Where I live power outages are common but short. Now, my primary machine is a laptop, so that will run for hours on battery (well, at least an hour), but since I need my cable modem and wireless router to connect to client systems if those devices loose power I’m basically out of business.

As I mentioned we have frequent power outages here in Concord, NH, USA but they are typically only a few seconds. That wouldn’t be a problem at all, except even a short power blip means I loose all my SSH connections! That can cause a 5 second power outage to cost me 15 minutes of work or more!

So, what do I have? Well, I’m partial to APC UPSs. They are what most of the data centers I have worked with use and they’ve got a great industry reputation.

Choosing a UPS

There are two major factors when choosing a UPS, Wattage and Volt-Ampres.

Wattage determines how much you can hook up to a given UPS. Devices generally give a wattage rating somewhere in the specs and power adapters often have them listed right on them. You’ll want to add together all the devices you wish to UPS (don’t forget about monitors) and purchase a UPS of at least that wattage, and probably a bit more.

Let’s say you have two computers which consume 85 watts, a monitor which consumes 120 watts, a cable modem which consumes 15 watts and a wireless router which consumes 7 watts (this is about my configuration.) That means I need a UPS which will support a maximum draw of at least 312 watts.

The Volt-Ampre calculation is a bit more complicated. This will determine how long the UPS will be able to supply power to your devices.

Correction: I had originally mistaken Volt-Ampre for Amp-Hours. Volt-Ampre is actually similar to watts except VA is more accurate for the complex power consumption in our computers. Higher is still better, but it doesn’t mean the UPS will necessarily last longer.

To determine the capacity of a UPS we would need to know the Amp-Hours of the battery. Unfortunately most (if not all) producers fail to publish this information so we the consumers are left trusting the manufacturers documentation to determine duration.

I ended up going with the APC Backup-UPS ES 650. At 65 VA and 450 max wattage for under $100 it was the right balance of cost and capacity for me. The delivered software also allows the unit to be connected via USB to a Mac or PC to adjust power management when running on the UPS similarly to how you can have different power settings on a laptop for when you are running on battery.

4 thoughts on “Working from home – A UPS to get you through those power blinks”

  1. This is a good reading about work from home.Brutally honest reviews of work at home opportunities and telecommuting sources are available at workathometruth.

  2. I think you have confused VoltAmps with AmpHours. VA is *equivalent* to Watts in a light bulb application. VA is higher than Watts in most everything else (that’s why UPS makers put the VA rating on the box, it’s a bigger number… MOICHENDISING!)

    AmpHours is the rating that we really need to know, but not one major !@#$ UPS maker prints that on the box. Because AmpHours *cost money*, so a high number (which is what we customers want) means high cost to the UPS maker. but I digress…

    AmpHours is the rating of the batteries in the UPS. e.g. a 12v gel battery I use for my home-brew off-road bicycle lighting system has 7Ah. That’s Seven Amps for an hour, or One Amp for Seven Hours… get it? (i.e. 12v*7A = 84W of power for an hour) That means that I can run my headlight, which draws 35W for right around two hours. I guess UPS makers thing we are all blithering idiots who can’t do simple math like this. *sigh*

    What we *really* need to know about UPSes is:
    How many joules (or 3600th watt-hours) does it have?
    What is the maximum load the inverter can handle? (this is where the Watts listed actually means anything)
    What kind of special power handling features (over/under voltage/current circuitry) does it have to obviate *switching* to the battery?
    What kind of surge/noise filtering does it have? (again, with *real* specs. not the obfuscating BS they give us)
    Maybe a couple of other things…

    but god forbid any company should actually be *clear* and concise about the specs of their equipment. *sigh*

    Sorry for the rant. I’ve been through the wringer with UPSes and the jerks/idiots who make/sell them. I hope amid my vitriol is some useful data.


    That’s about it.

  3. Thanks for correcting me Captain! I was in fact thinking of Amp Hours not Volt Amps. And of course you’re also right that the producers don’t provide this information.

    Sooner or later one producer will decide to mark them properly and others will change to compete. For now, most consumers don’t know the difference. Sad, but typical.

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