Technology Explained

5 Things You Need To Know In Order To Buy The Right UPS

Kannon Yamada 27-08-2017

Power is unpredictable. A car crashing into a pole or a small flaw in a transformer can cause a blackout or a surge strong enough to destroy most electronics in your home. Although rare, these events can knock your computer out when you need it most. It can even cause thousands of dollars of damage.


The solution is not any mere surge protector but instead an Uninterruptible Power Supply (UPS). These big, beefy units combine a high-quality surge protector with a backup battery that will keep electronics running through a blackout (for a short time, at least). Here’s what you need to think about before making the leap to a proper UPS.

How Many Outlets Do You Need?


Like a surge protector Are Surge Protectors Necessary? Here's What They Really Do A surge protector is not the same thing as a power strip! Here's how they're different and why you need a reliable surge protector. Read More , a UPS only has so many outlets. That’s why you must determine how many devices absolutely must be plugged in. For small or home office purposes, that usually only amounts to a router, modem, and sometimes a mini server. However, for larger businesses, your needs might be greater. Generally speaking, it’s a good idea to buy whatever you need plus two, as that gives you some flexibility for the future.

However, keep in mind that many UPS units only provide surge protection on some ports. The outlets powered by the battery will likely be less than the maximum number of ports. Inexpensive options often cut costs by only providing battery backup to four or six outlets, leaving the remainder unpowered. That’s won’t be a problem for everyone, but it can be a nasty surprise if you learn about it the first time the power goes out. Fortunately, you’ll notice just by looking at the UPS whether or not it has ports without backup power.

Finally, if you’re using wired data connections, look for a UPS that provides protection for them as well. This includes both old-fashioned modem and newer Ethernet connections.


How Much Power Do Your Devices Require?


5 Things You Need To Know In Order To Buy The Right UPS killawatt

With your outlets handled, you’ll next have to ask yourself how much power the devices connected to the UPS will consume. If the devices need more power than the UPS can generate, they’ll go dead, even if the battery has plenty of energy remaining. Think of it like a computer’s power supply; if the wattage is lower than what the computer needs, you’re out of luck.

You can find out how much power your PC (or other equipment) uses How Much Power Is Your PC Using? Computer power consumption can be estimated. Most of the components inside a PC have specific minimum and maximum power draw figures and, because quality control is so tight, it’s rare of a part to break... Read More with a wattmeter, which can be purchased online for about $15. Remember to check the consumption of everything that you need to power. If you want to power a desktop PC, for example, you need to add together the wattage of the computer and the monitor.
P3 International P4460 Kill A Watt EZ Electricity Usage Monitor P3 International P4460 Kill A Watt EZ Electricity Usage Monitor Buy Now On Amazon $38.90


The amount of power supplied by the unit is often written just before the letters “VA” (or Volt-Amps). Unfortunately, it’s not possible to convert from VA to a recognizable number, like watts unless you know the Power Factor (PF) rating of a UPS. A very rough (and not usable) estimate would be to approximate VA as watts. So, for example, the CyberPower 1500VA can at peak, supply up to 1,500-watts of power if the PF is near 1. Lower power factors could result in a UPS that doesn’t supply enough juice — so you may want to purchase around 20% more VA than you need.

How Long Do You Need To Run On Battery?


Now that you’ve handled the wattage, you should also think about how long your devices need to run. Some buyers purchase a UPS because they want a few minutes to shut down devices properly and save any work that was performed on them. Others want a UPS so they can work through blackouts which may last as long as an hour.

By the way, if you’ve configured Windows properly, it should automatically shut down once power loss is detected. I


To figure out how long a UPS will power the devices you’ll connect, add together the wattage they draw and then refer to the product’s runtime/load graph. Usually, this can be found on the side of the package or, if you’re buying online, in the description. The APC BR1000G Pro, for example, can power 400 watts of equipment for about nine minutes or can power 100 watts of equipment for an hour.
APC 1500VA UPS Battery Backup & Surge Protector with AVR, Back-UPS Pro Uninterruptible Power Supply (BR1500G) APC 1500VA UPS Battery Backup & Surge Protector with AVR, Back-UPS Pro Uninterruptible Power Supply (BR1500G) Buy Now On Amazon $216.43

What Features Do You Want?


You might think that the features of a UPS would be simple. You plug in devices, and when the power it goes out, the battery kicks in. That’s all there is to know, right?

Nope. Even basic consumer-level units offer features like disconnecting battery notification, USB connectivity and a software suite that can be controlled via PC to fine tune settings and see how much power is being consumed. A beefier “professional” unit offers even more features, such as a LED that reports remaining battery charge and runtime in minutes, and hot-swappable batteries.


Most people won’t need such fancy extras, but simply knowing that they exist is important. You’re paying for it, so why buy a UPS with fewer features, if all other things are equal?

How Good Is The Warranty?


A UPS normally lasts as long as its internal battery — and generally, that’s around two-three years. The reason is that batteries decay over time, particularly when fully charged. And UPS batteries — by default — are charged all the time. Because of its battery, almost all warranties max out at around three years — just long enough to cover the lifespan of the battery. Fortunately, some UPCs offer insurance on top of a 3-year warranty. For example, APC’s policy includes a $75,000 insurance policy and data recovery with Ontrack — but only on some products. Double-check before buying.

As such, I heartily recommend APC products to anyone concerned principally about their backup battery’s reliability. Of their vast product selection, one of the best APC UPSes out there is the APC BE650G. Its battery is replaceable, it receives high marks from reviewers, and it offers just enough juice to keep your home office or small business afloat during a power outage. For larger power needs, though, you might need to look elsewhere.
APC UPS, 650VA UPS Battery Backup Surge Protector, BE650G1 Backup Battery, Dataline Protection, Back-UPS Uninterruptible Power Supply APC UPS, 650VA UPS Battery Backup Surge Protector, BE650G1 Backup Battery, Dataline Protection, Back-UPS Uninterruptible Power Supply Buy Now On Amazon $75.99

Of course, there’s the potential for gotchas, so you should probably read the warranty online at the UPS manufacturer’s website before buying.

Note: To clarify, UPS batteries are designed to be serviced. Most just pop out. So when the battery fails, you normally only need to order a replacement.


Do you already own an uninterruptible power supply? Leave a comment letting us know about your experience. There are many UPS devices on the market, and they tend to vary from region to region, so reader tips can help add to the discussion.

Image credit: Komjomo via, Wikimedia/Zátonyi Sándor

Originally written by Matt Smith in September of 2013.

Explore more about: Buying Tips, UPS.

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  1. Oron
    August 28, 2017 at 10:48 am

    Just a small correction. Most UPSs, if not all, use lead-acid batteries, not lithium-ion.

    • Kannon Yamada
      September 2, 2017 at 2:49 am

      Wow, that explains why they only last a few minutes. :-) Thanks Oron!

  2. likefunbutnot
    August 27, 2017 at 5:31 am

    Batteries need to be replaced every couple years to keep the unit in working order. I've never used one that didn't have easy access for service.

  3. Ashish
    November 23, 2015 at 4:00 pm

    Hey I have a gaming PC with a 550 watt smps.But it uses a big less.Will the APC br1000 pro do ???if not suggest me the best one.Im from India.

  4. Ashish
    November 23, 2015 at 3:49 pm

    Hey I have a gaming PC with 550 watt smps but uses a bit less.will the APC br1000 pro do ??if not suggest me the best from India

  5. Adam
    September 12, 2013 at 2:39 am

    Going along with power consumption part of this article, always size the UPS based on watts or kW. Its always smaller than the highly advertised VA or kVA rating. sometimes nearly half that value! A 750 VA UPS may only be able to support 400 watts of power.

    I've been a UPS technician for several years, usually working on the much larger brothers of these little guys, and will tell you overloads with these little guys happen all the time due to that.

  6. Victor G
    September 11, 2013 at 11:32 am

    The article failed to mention the quality of the signal that the UPS generates. Like Joe above mentions, some equipment needs cleaner power than others. A pure sine wave is clean. A lot of cheper UPS' generate a step quasi-sinewave instead of a true sinewave. That is distorted power, has higher harmonic frequencies (more then the 60 Hz that is standard) and can damage your sensitive equipment. True sinewave units generally cost more than equivalent step sinewave units.

  7. Tom E
    September 11, 2013 at 11:24 am

    Here's another "feature" to consider. *WHEN* the internal battery dies (after 3 years or so), what are you going to do? With many of the UPS's, you can take the old battery out and replace it; I'd make sure to buy a UPS with an easily replaceable battery. The APC shown in the photo has a "door" in the back that slides away, revealing the battery. It cost about half of a new UPS, and the battery place I took it to recycled the old one. Win-win!

    • Anonymous
      August 15, 2015 at 6:53 pm

      Good point. I checked my UPS and I can replace the battery at less than half the cost of a replacement. Thank you.

  8. Joe
    September 11, 2013 at 3:50 am

    Many Power supplies especially newer ones require certain features to function properly. I know very little about it but many power supplies are PFC and work much better with Sine Wave battery backups.

    I have no idea what that means, I do know that my APC (similar to the one pictured above) would not keep my system running. I got a CyberPower Pure Sinewave and now it hums right along.

    perhaps someone more knowledgeable could fill in the blanks.

  9. Abhishek R
    September 11, 2013 at 3:49 am

    currently i am having a very low end ups, connected with my only one pc. I wanted to purchase another pc and if a connect that to my ups could it give me some problems or its just fine.

  10. Hildy J
    September 11, 2013 at 3:43 am

    One thing about unpowered outlets, they are mandatory for laser printers which will suck your battery dry in no time. They are also useful for things you can live without in a power outage like second monitors.

    Also, think about brownouts. A UPS that runs power through the battery and cleans it constantly can save your equipment. If you've got an expensive TV, you might want a UPS just to scrub the power.

    Lastly, look for a company that provides a battery replacement program. Chances are that absent close lightning strikes your UPS will outlast its batteries.

    I have an APC Smart UPS for my PC and a Belkin Pure AV for my plasma TV and I'm pleased with both.