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After researching more than two dozen models, interviewing experts, and having an electrical engineer test our top candidates, we found that the CyberPower CP685AVR is the best uninterruptible power supply (UPS) for people who want to keep a home network running during a blackout of an hour or less. It’s easy to set up, it has some of the most positive user reviews in its class, and it’s the most affordable unit we found. We also like the APC BE650G1 Back-UPS, if it’s available for less. But if you need to power more than a modem and a Wi-Fi router or if you need to stay online longer, the APC BR1000G Back-UPS Pro is a better choice, with more than twice the power for less than twice the price.

The CyberPower CP685AVR will cover the basics for most people during short blackouts. In our tests it provided enough power to keep the average cable or DSL modem and Wi-Fi router running for an hour, which means you can stay online to pass the time while the lights are off—or, in a real emergency, keep your digital phone service powered so you can reach the outside world. The size of an overgrown surge protector, the CP685AVR is small enough to hide in the same corner as your networking gear, and because it has surge protection built in, you’ll have one less thing to buy. Although you could easily spend more on a UPS, you really have no reason to if you need only basic, non-critical protection and a limited amount of power.

When we tested the CyberPower CP685AVR alongside the APC BE650G1 Back-UPS, the CyberPower lasted longer and stayed truer to its stated rating, but the difference was less than five minutes of uptime on average—59.6 minutes of power versus 55.8. Both units also have surge protection on all eight outlets, the same three-year warranty, and no status display. If you can get the APC BE650G1 for less than the CyberPower, it will serve you just as well.

If you’re going to have more devices plugged in, or if you need to be able to use them longer in a power outage, the APC BR1000G Back-UPS Pro offers some extra juice. It’s almost twice the price of our top pick, but it will last more than twice as long when powering a 50-watt load such as a modem and Wi-Fi router—about 2 hours, 15 minutes in our tests. Even with its larger battery, the BR1000G can keep a 300-watt load like a desktop computer and peripherals running for only about 15 minutes, which may be just enough time for you to save your game progress, or check in with co-workers before being banished from the connected world.

Why buy a UPS?

This kind of battery-based power-backup system is basically a surge protector, a battery, and a power inverter wrapped into one unit. Consider this: When you stream an online video to your computer or phone, the video player first takes a few seconds (or minutes) to get some of the video data into a buffer so that if your Internet connection is inconsistent while you’re watching, you still get smooth playback. A UPS is a similar buffer but for your electricity, in that if your power dips temporarily or goes out completely, anything plugged into the UPS can continue to draw power from the buffer, unaware of a problem. Although the buffer—the battery inside the UPS—will eventually run dry, it should keep you online during short blackouts.

For many people, a UPS falls into the murky gray area between need and want. If you have a desktop computer or network-attached storage, you may need a UPS to prevent your drives from losing data in the event of a sudden power outage. And if you have digital phone service through your broadband provider, and the company skimped on your equipment by not including a battery, you may need a UPS to power your phone modem during a blackout so that you can reach emergency services. But a UPS is also handy during mundane power outages, because it allows you to pass the time on Facebook or Netflix while you wait for the juice to return.

Although a UPS makes sense in a lot of scenarios, there’s no need to spend money on a bulky UPS when all you need is surge protection. Nor is a UPS the right choice to keep an extensive home theater powered up, or to run most any household appliance—if your needs are on that scale, you might want to consider a home generator, or a battery system designed for off-grid power. Similarly, if you’re trying to figure out how to power electronics far from the grid, companies such as GoalZero and Renogy offer a more appropriate option.

How we picked and tested

To find the best UPS for most people, we looked at the power output, battery capacity, and user comments on 28 of the highest-rated and most-popular UPS options on Amazon. The field mostly consists of products from established brands such as APC, CyberPower, and Tripp Lite, with a few smaller brands sprinkled in.

When you’re deciding what size UPS you need, you’re actually assessing two different things: power output and battery capacity. Most UPS models have their maximum output, rated in volt-amps (VA) or watts (W), right in the name. But that number indicates only how many watts the UPS can provide—that is, how much gear you can plug in—at once. How long the battery lasts will depend on how much gear you connect to it: The more devices the battery has to power, the less time it will give you. As you move up in maximum output, battery capacity sometimes follows, but not always, so it’s important to find and compare both ratings.

For our pick—which we chose based on the product’s ability to keep a home network up and running—maximum output was less of a concern than capacity. A combination of a 60W modem and router won’t be a problem for even basic UPS units, which tend to put out around 350VA (roughly 200W). So instead of focusing on output ratings, we focused on capacity—specifically, how long each UPS could keep 50W of equipment running.

We also looked for models with the additional power output and capacity that a workstation UPS needs. When we tallied up the power consumption of a modern tower desktop (around 150W), our favorite 27-inch monitor (88W maximum), our favorite hard drive (10W to 15W), and the same modem and router we used as a guideline for our top pick (60W), we barely pushed past 300W. Because most residential UPS options in this range have only four battery-powered outlets anyway, you’re unlikely to need a much higher output than that.

However, to get reasonable run times, we found that it was worthwhile to move up to around 1,000VA, or about 600W. With a UPS that size, you’ll generally get 15 minutes or so to finish your current task and power down a 300W rig, or a couple of hours to keep 50W of Wi-Fi gear running.

For each tier, network, and workstation, we tested one model from APC and one from CyberPower, the largest and most popular manufacturers in this performance range. Models such as the Tripp Lite AVR650UM cost more and had fewer reviews, and offerings from Eaton were more expensive and weren’t intended for home use. In the end, the model variations from APC and CyberPower had the broadest appeal, and had detailed, positive user reviews. They offered some of the best dollar-per-minute measures of value, too. We sent all four—the CyberPower CP685AVR, the APC BE650G1 Back-UPS, the CyberPower BRG1000AVRLCD, and the APC BR1000G Back-UPS Pro—to an electrical engineer, Lee Johnson, who set to work testing them and disassembling them to assess the quality of their components and construction.

Because most electronics vary their energy consumption depending on their task, we decided to build a test rig that provides a more consistent load than, say, a laptop or router. Johnson wired 10 light sockets to accept 50W halogen bulbs, added a USB data logger to track run time, and used a Kill-A-Watt meter combined with a true-rms multimeter and an oscilloscope to verify the power levels, giving us the option to replicate tests as necessary.

50W load

time to shutdown (minutes) 300W load

time to shutdown (minutes) Model Test A Test B Test C Average Test A Test B Test C Average CyberPower CP685AVR 65.0 58.5 55.2 59.6 4.4 4.7 4.7 4.6 APC BE650G1 Back-UPS 53.9 58.5 55.1 55.8 5.5 5.7 5.6 5.6 CyberPower BRG1000AVRLCD 75.1 67.3 72.9 71.7 7.1 7.3 7.4 7.3 APC BR1000G Back-UPS Pro 131.1 133.3 138.1 134.2 17.0 15.9 16.3 16.4

We allowed each UPS to charge for 12 hours before each test. We first gave each unit a 50W load until it shut down, repeating the test three times. We then repeated the process at 300W. When we averaged our results, the data showed clear winners for both classes, though a different brand won each class.

Every major UPS comes with some basic surge protection built in, which is good because you shouldn’t plug your UPS into a surge protector, or plug a surge protector into a UPS. Unfortunately, most affordable UPS units don’t offer much protection compared with a dedicated surge protector; Johnson took apart our samples and found only basic protections inside. The APC also has the advantage of extra capacitors and filtering circuits to help keep the power steady. The CyberPower CP685AVR won’t take as many hits, nor ones as large, but both the APC and CyberPower models have the advantage of an extra transformer that acts as a buffer between the wall and your gear, and creates line interactive topology (some manufacturers refer to this as automatic voltage regulation, or AVR). If the voltage from your home sags or swells within a certain range, the transformer corrects it for your equipment without the UPS needing to switch to battery or divert power to the surge-protection circuits.