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.