From The Wirecutter: The best uninterruptible power supply (UPS)


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 modemand 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 Eatonwere 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—theCyberPower CP685AVR, the APC BE650G1 Back-UPS, the CyberPower BRG1000AVRLCD, and theAPC 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.

Our DIY load generator isn’t as accurate as a lab-grade programmable load, but at 50W per bulb, it can drain a UPS with an AC load as high as 500W and measure the run time with a USB data logger, giving us enough data to assess UPS performance for home use.
Our DIY load generator isn’t as accurate as a lab-grade programmable load, but at 50W per bulb, it can drain a UPS with an AC load as high as 500W and measure the run time with a USB data logger, giving us enough data to assess UPS performance for home use.

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.

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.

Our top pick, the CyberPower CP685AVR (left), and our upgrade pick, the APC BR1000G Back-UPS Pro (right), with their batteries removed. The guts of a UPS are focused on providing backup power, not surge protection.
Our top pick, the CyberPower CP685AVR (left), and our upgrade pick, the APC BR1000G Back-UPS Pro (right), with their batteries removed. The guts of a UPS are focused on providing backup power, not surge protection.

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.

The CyberPower CP685AVR sits under your desk like an overgrown surge protector.
The CyberPower CP685AVR sits under your desk like an overgrown surge protector.

The UPS units we’d get: Our picks for a home network

The CyberPower CP685AVR is our first choice for anyone who wants a UPS to keep their home network andmodem online until the power comes back up, though the APC BE650G1 Back-UPSis just as good of a pick if you happen to find it for less.

Most people are looking for a UPS to solve one of three problems in a blackout: powering a digital-phone modem for contacting emergency services and loved ones, preventing damage to something that needs to be properly shut down, or passing the time until the electricity comes back. The CP685AVR can keep a combination of a common 50W cable or DSL modem and Wi-Fi router on for about an hour, or a 300W workstation online for a few minutes while you frantically save work and safely shut everything down.

We tested the CP685AVR against APC’s closest competitor, the BE650G1. Though the APC unit had a much longer advertised rating at a 50W load—87 minutes versus 59 minutes—the CyberPower unit edged it out in our real-world tests, averaging 59.6 minutes compared with APC’s 55.8 minutes. We ran each test three times on a single sample of each device, so numbers this close are not definitive, but in the end the CyberPower unit performed to its rating and the APC unit under-delivered. Without any other differentiating factors, that’s just enough of an advantage to make the CyberPower CP685AVR, which is often a few dollars cheaper, our top choice.

You won’t find many in-depth editorial reviews of the CP685AVR or most other battery-backup units. UPS comparison isn’t a sexy topic, and the units aren’t easy to test. But CyberPower’s AVR Series has user reviews dating back almost 10 years. Although we’ve become wary of user-review averages for some product categories, CyberPower isn’t a no-name brand, and the UPS’s review distribution is what we expect to see for a good product with fair reviews—mostly five- and four-star ratings, trailing off until you get to a slight uptick of one-star reviews that often overrepresent the rate of failure. For the most part, users have found the CyberPower offering to be a competent UPS, which is about what you’d expect for a utilitarian device.

Our simulated workstation, drawing 300W of power, was near the maximum output of both units. Because battery life isn’t linear, a slightly higher draw can lead to a greatly reduced run time. Though both models in our tests ran a 50W load for almost an hour, when powering our 300W load the APC BE650G1 averaged only 5.6 minutes and the CyberPower CP685AVR squeaked out just 4.6 minutes. As with the 50W test, these results are close enough to be a tie, and just enough time for you to quickly save your work and safely shut your computer down.

The other similarities between the CyberPower and APC units outnumber the differences. Both devices provide eight outlets, four of which have battery backup and surge protection, and the other four offer only surge protection. Both units have all the appeal of a rectangular block and lack any screen or status display. If you want to monitor or manage either one, you’ll need to connect it to your computer with a USB device cable and install the included software. Though CyberPower’s model can provide 15W to 20W more power than the APC device, that doesn’t mean much in the real world. If anything goes wrong, both companies provide a three-year warranty.

At this level, a UPS is a basic, utilitarian device, and both APC and CyberPower are reputable companies. When Amazon has both models in stock, their prices tend to be only a few dollars apart—pick the cheaper one, and you’ll have some peace of mind the next time a thunderstorm rolls in.

For powering a workstation

Our pick from APC is smaller than a tower computer, but you’ll probably want to position it like one so you can see the status display on the front.
Our pick from APC is smaller than a tower computer, but you’ll probably want to position it like one so you can see the status display on the front.

If you want to keep your network up for more than an hour in a blackout, or if you plan to have 100W to 300W worth of stuff plugged in to your UPS, the APC BR1000G Back-UPS Pro is the way to go. This 24-pound minitower, measuring 3.9 inches wide, 9.8 inches high, and 15 inches deep, holds a higher-capacity battery and higher-output inverter capable of around 600W. In our tests, the APC BR1000G lasted almost twice as long as the similarly priced CyberPower BRG1000AVRLCD.

Though it seems like a 300W model should be able to run a 300W load, the reality is that you want to have the power to do anything more than save your work, you shouldn’t load a UPS with more than 50 percent of its rated output. This means that if you’ll be plugging in around 300W worth of equipment—that’s a desktop computer, a 27-inch LCD monitor, an external hard drive, a cable modem, and a wireless router, with some room to spare—your UPS should be rated around 600W or more.

To quickly convert an advertised volt-amp rating to something more useful, you can cut the VA figure in half to get the rating in watts and then cut it in half again to estimate the load that you’ll be able to run for a reasonable amount of time. So a 1,200VA UPS might be rated for about 600W, which would be about right for a 300W workstation. Such an estimate errs on the safe side to make the calculation simple, because a truly accurate calculation depends on which variable you put into an engineering equation that you don’t really have to care about. (You can go read theseif you do care.)

Even with higher loads, the APC BR1000G performed well in our tests. With a 16.4-minute average, it bested its advertised 14-minute rating by a couple of minutes, and the CyberPower model averaged only a little over seven minutes of run time with our 300W load. When the power goes out, a few extra minutes make a big difference: You can finish the email you’re typing, or shut down a set of spinning NAS drives.

If you’re running only your network equipment, the amount of extra time you get is even more dramatic. The APC BR1000G ran for an average of about 134 minutes with our simulated 50W network-equipment load, almost twice as long as the CyberPower BRG1000AVRLCD, which lasted for only 72 minutes. Based on those results, at the time of this writing the APC costs less than a dollar per minute of backup power, making it an even better value than our home-network pick. Though the prices of both workstation units regularly fluctuate, they generally do so by only a couple of dollars.

As with our smaller picks, few editorial reviews or tests are available for the APC BR1000G. But even though this model hasn’t been around as long as our smaller-load pick, it has quite a following, with almost 2,000 user reviews on Amazon dating back to 2010. No matter the exact size, users report similar pros and cons for this UPS lineup as for our other picks: They do what they claim to do, they aren’t great surge protectors, and they might not work with high-end desktop PCs. When you keep those realistic expectations in mind, the BR1000G is great for what it’s supposed to be.

Once you’ve decided to spend more than $100 for a UPS, getting a model with a status display doesn’t cost much more than a unit without one, and they’re convenient. Talking about the APC BR1500G, a larger model with the same display as the APC BR1000G, Wirecutter editor Dan Frakes said, “The LCD is really useful for seeing how much estimated time is left, viewing the battery charge level, and getting diagnostic info. All my UPS units have LCDs now, and I wouldn’t want one without a display.” Below its display, the CyberPower BRG1000AVRLCD has USB outlets that the APC BR1000G lacks, but with the latter model, that’s a small sacrifice for such a huge performance gain.

Once the price goes above $100, a status display like the one on the BR1000G isn’t a perk, it’s a requirement.
Once the price goes above $100, a status display like the one on the BR1000G isn’t a perk, it’s a requirement.

The APC unit clearly performed better in our tests, but the rest of its feature list is common among UPS models in this price range. The APC and the CyberPower each have four outlets protected by battery and surge protection, along with four that provide only surge protection. Both companies supply proprietary software that you can install to monitor your UPS over USB, as well as to set the software to safely and automatically shut your Windows computer down during a blackout. (Apple’s OS X includes a built-in feature that does the same thing when the UPS is connected via USB.) CyberPower does offer a five-year warranty versus APC’s three-year coverage, but we’ll take the performance gains of the APC model over two years of extra protection for a unit that doesn’t perform as well.

Care and maintenance

Keep in mind that high-drain devices—including large office equipment such as laser printers and paper shredders, as well as anything that makes heat, like a space heater or curling iron, or any type of medical equipment—can damage a UPS’s components and degrade its battery. Such use may also void the UPS’s warranty, so check the manual.

Do not ever plug a UPS into a surge protector, or plug a surge protector into a UPS. Aside from potentially overloading either unit and tripping a fuse or breaker, you also risk canceling out the surge protection function instead of doubling it up.

The sealed, lead-acid battery inside your UPS will stay charged as long as the device is plugged in, so it should be able to perform well for many years. But because batteries degrade over time, you can avoid any surprises in the future if, once a year or so, you unplug it with your devices running to make sure it powers them as long as you expect it to.

About the VA rating

A volt-amp is equal to power (in watts) divided by a power factor (a measurement of how well a device turns the apparent power of a circuit into real power). But don’t get too hung up on a UPS’s VA rating—instead, look for a wattage rating buried in the product listing or, if you can’t find the wattage rating, assume that it’s half the VA rating.

If you’re interested in electrical theory, or comfortable with algebra, here’s the background on why this is the case: In basic electrical theory, watts (W) = volts (V) × amps (A). Except AC-powered electronics are more complicated than that, so in actuality, watts = volts (V) × amps (A) × power factor correction (PF). Often, PF = 1, which means that VA does indeed equal W. But sometimes PF is 0.5, or 0.7, or anywhere else on that spectrum, so manufacturers have stuck to using the VA rating out of tradition and an abundance of caution. We asked Tim Derochie at CyberPower about the topic, and he let out a knowing chuckle before we even finished the question. Nobody particularly cares for this bit of confusion, but it probably isn’t going anywhere.

Premium features you might consider

If you have more-complex needs than simple protection at an affordable price, or you have a bigger budget, you can find additional UPS options to choose from, including extendable battery capacity, more-compact lithium-ion batteries, and pure-sine-wave power.

Compared with the sealed lead-acid batteries (similar to a car battery) that most UPS manufacturers use, lithium-based batteries (like that of a laptop) can provide much more energy from a much smaller mass and, in many applications, can last years longer. However, those benefits are currently outweighed by per-minute run-time costs that are almost twice as high, and UPS manufacturers are just starting to experiment with them.

APC markets the compact BGE50ML specifically for keeping home networks running. It’s about half the size of our home-networking picks above, but APC’s claim of over two hours of run time is based on a 10W load—we had a hard time finding a common network configuration that would use so little power. Although your gear may not run at its maximum load all the time, 50W is a more common maximum load for a home modem and router; with that load the BGE50ML is rated for only about 30 minutes. The model’s other premium feature is a removable USB battery pack that you can use to power a tablet or smartphone on the go.

A few Wirecutter editors recently picked up APC’s more reasonably priced BGE90M, which is similarly aimed at low-power network devices but lacks the removable USB battery. In one editor’s real-world power outage, the BGE90M kept a router and modem going for almost an hour. But with only three ungrounded outlets and not even a token amount of surge protection, it doesn’t have the broad appeal that our picks do—though the price is tempting, because frequent sales bring the expected run-time value down to less than a dollar per minute.

The output of our upgrade pick, the APC BR1000G, isn’t quite a pure sine wave, but it should be clean enough for most electronics.
The output of our upgrade pick, the APC BR1000G, isn’t quite a pure sine wave, but it should be clean enough for most electronics.

Though the move to lithium-based batteries may still be a ways off, the current trend in UPS products is making pure-sine-wave inverters the norm. Batteries store and release power as direct current (DC), but residential outlets use alternating current (AC). Whereas DC power shoots through electrical wires, AC flows like waves, oscillating up and down. To turn DC power into AC power, you need an inverter that makes those waves. Manufacturers market the cheapest inverter option as a modified-sine-wave inverter, but it would be more aptly called a stepped-approximation (or square-wave) inverter. Instead of making a true wave, it steps the power up and down quickly. For many electronics, this approach is okay, if a bit inefficient.

But for some devices, square waves can cause problems, from buzzing you can hear with audio equipment to flickers in tube-based displays to melting plastics and mystery smoke. Perhaps counterintuitively, expensive electronics such as laptops are often fine with such inverters thanks to more-refined power supplies that can better handle sub-par power. A CyberPower representative told us that the company can never predict which products will have problems, but for mission-critical gear or for gaming rigs that tend to be finicky about power supplies, the representative recommended upgrading to CyberPower’s PFC Sinewave series of UPS models.APC and other manufacturers are offering more pure-sine-wave options, as well.