Backup Battery Power - What You Need to Know

Category: Hardware

A concerned reader asks: 'Do you recommend a backup power supply for computers? During the last storm, my PC crashed and we lost power for several hours. If I had a battery backup, I could have saved my document, and gotten online to check for email and weather updates. I've read about Uninterruptible Power Supply units - is that what I need?'

What Kind of Backup Power Do You Need?

A sudden loss of electrical power can cause your computer to shut down or reboot. Of course, you will lose anything you were working on at the time of the power glitch. But power failures can also cause head crashes in hard drives, which can damage a disk and the data on it. To guard against power failures, I do recommend that you get an uninterruptible power supply (UPS) to provide a backup power source for your computer.

A UPS, at its core, is a battery backup power supply. It includes circuitry that instantly switches from line power to battery power in the event of a power outage. The simplest and cheapest type of UPS, called a standby UPS, does nothing more. But power outages are not the only hazards your computer faces.

Fluctuations in line power quality are much more common than blackouts. A voltage spike or its opposite, a voltage drop, can adversely affect your equipment's performance and lifespan. If you live in an area where the lights sometimes flicker, or the power drops for just a second a comes right back, your computer could be damaged. Protections against these types of electrical power hazards should be part of your UPS.

UPS battery backup

A line-interactive UPS is also relatively inexpensive; it filters and conditions line power as well as providing battery backup. An on-line UPS provides the highest quality line power and the greatest protection against power outages. Most home computer setups require no more than a standby or line-interactive UPS.

What Features Do You Need in a UPS?

A UPS may include other features as well. Monitoring ports on a UPS can tell attached equipment to shut down gracefully in the event of a power outage, in case no one is around to shut things down manually. Fax and modem telephone-style outlets may be provided on a UPS to give these devices surge protection. Some unprotected power outlets may exist for printers and other devices that do not need backup battery power but should be protected against power fluctuations.

The capacity of a UPS is measured in volt-amperes (VA). How much capacity you need in a UPS is a function of the power needs of all the components you wish to protect and the amount of time that you want to be able to run on battery power. APC, a major UPS manufacturer, has a handy calculator that can help you determine what the capacity of your next UPS should be. Plug in the devices you have (desktop, laptop, monitor, and peripherals) and it will estimate the power needed to keep them running, and give suggestions for APC products that will do the job.

One of the most popular consumer-level UPS models is the APC Back-UPS 600VA ($57) which provides battery backup and surge protection for your home computer, router, and peripherals. It has 7 total outlets (5 provide both battery backup and surge protection; 2 offer surge protection only). There's also a USB charging port for your smartphone or tablet. APC says the battery in this model should last 3-5 years, and are replaceable. This model gives you about 25 minutes of battery backup with a 100-watt load. That's enough time to save your work and shutdown, but not a good solution if you want to stay up and running during a longer power outage.

The APC 1500VA Back-UPS Pro ($159) is a significant step up. It has 10 outlets, and will keep your gear powered up (100-watt load) for 68 minutes. A display on the unit will tell you how many watts are in use, and the amount of battery time remaining.

Another popular UPS model to consider is the CyberPower 900VA ($99). It offers 6 battery backup & surge protected outlets, and 6 surge protected outlets. Data line protection prevents power surges that travel through telephone, coaxial and ethernet lines. CyberPower has a 3-year warranty, including the replaceable battery.

The Tripp Lite 1500VA ($162) is also highly rated, and provides up to 90 minutes of runtime for an entry level PC system. Includes user-replaceable batteries, software to enable unattended system shutdown, and 3-year warranty.

Amazon Basics also has a lineup of Standby UPS models, ranging from 400VA ($39.99), to 600VA ($49.99), to 800VA ($79.99).

Don't Forget About Your Internet and Phone and TV

During a storm or other hazard, it's quite possible that the electrical supply lines might be down, but the telephone, cable or fiber optic lines are just fine. A battery backup unit can power your landline phone's base unit, as well the modem/router for your Internet connection. Some internet service providers install an interface box with a battery backup unit. When I had Verizon FIOS service, that battery would only last about 15 minutes. So during power failures, I plugged the FIOS battery backup into a UPS so I could continue to make phone calls and exchange electrons with the Interwebs. For outages longer than a half-hour or so, a gas-powered generator will be necessary.

I've found that purchasing a gas-powered generator is a great way to ensure that you'll never need one. In 2012, Hurricane Sandy heavily damaged the power infrastructure in my area, resulting in outages that lasted for several days. The year before, Hurricane Irene also knocked out power. I assumed that we'd be seeing more of the same, so I purchased a beefy gas-powered generator. But in the past seven years, we've had no outages lasting more than a few minutes. Your mileage may vary.

It's important to conserve every watt of power when running from backup power. So if you have your computer and other gear connected to a UPS, I recommend turning off the printer, speakers, external hard drives and other non-essential items unless you're actually using them. I have a dual-monitor setup, so I power one of them down, too. Laptops and tablets use a lot less power than desktop rigs, so consider moving to a smaller screen when running on auxiliary power.

But I Already Have a UPS...

I had a Tripp-Lite TE-600 UPS for many years, and there were many times when the lights flickered in the house, causing televisions and alarm clocks to shut off or reset. My computer never even flinched. Even during power outages, my trusty computer plugged away, while the rest of the house was dark. But during the winds that Hurricane Irene brought to my area, we lost power and my UPS failed when the internal batteries died of old age. Fortunately, I only lost the document I was working on, and I've since replaced that unit with a beefier model that'll run my desktop appliances for at least 30 minutes.

A UPS contains a battery, of course; typically, a lead-acid battery much like the one in your car. Such batteries are generally good for several years, but eventually they do need to be replaced. UPS units and replacement batteries are available online, but pay close attention to shipping charges; these things are heavy and expensive to ship! I found a good deal on a $12 battery from BatterySharks but the shipping cost added another $10. You might want to shop locally when purchasing a UPS or replacement batteries.

Do you have a battery backup UPS? Post your comment or question below...

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Most recent comments on "Backup Battery Power - What You Need to Know"

(See all 26 comments for this article.)

Posted by:

Neil C. Hopkins
07 Mar 2019

I have a $3,500 TV. You better believe I have it protected with a $200 APC UPS.

Posted by:

James Green
07 Mar 2019

your example of 100W for power use is way under par for most desktop units and displays. A good plan is to get a power monitor device to see how much you are actually using, and plan from that. Also, NEVER EVER plug a laser printer into a UPS. If it cycles from standby to ready, it will eat your UPS battery's lunch! Most UPS units would not be successful in powering a Laser printer through one cycle...

Posted by:

07 Mar 2019

A few years ago I bought a pricey Honda generator to prevent outages. It has worked well; the longest outage was only three hours, which I toughed out.

Posted by:

James Wray
07 Mar 2019

I have a CyberPower 1000VAC model. I put my laptop into the battery side when charging in case power goes out while I'm using it while charging just in case power goes out with a low battery. Have not had any issues with it. I will have to find a battery for it when it dies.

Posted by:

07 Mar 2019

Bob, Thanks for an informative article. I have used APC back-up batteries for years and can vouch for their effectiveness.
I agree with Dave that the modem/router also need to be plugged into the back-up as well as the computer itself.

Posted by:

Michael Burks
07 Mar 2019

I can not help thinking you should have made some mention of sinewave vs. stepped wave output. Some devices choke on stepped wave power.

Posted by:

07 Mar 2019

I have surge protection through The solar system for our whole house. It even has a very large LG battery and when the power does go out (rarely) it powers my office (desktop,laser printer,TV,etc) and essential appliances. We haven't been on the grid for 8 months now.

Posted by:

07 Mar 2019

It is hard to imagine someone, even you, working on a document during a hurricane. Surprised a document is the only thing you lost.

Posted by:

07 Mar 2019

It is even harder to consider that someone would spend $3500.00 just to watch TV.

Posted by:

07 Mar 2019


Sure, a UPS is a great idea, but-
I have had APC and Eaton units. Both became defective in a very short time.

If you look at the Amazon comments for all of these units and brands, seems like lots and lots of folks have had lots of problems with all
the name brands. Also, several fires and smoking units.
Real scary.

The impression one gets is that nobody knows how to make a reliable, under $200 or so, unit.


Posted by:

07 Mar 2019

Several years back, had all the computers at the company I worked for, connected to APC battery backups. As well as at my home.
We would lose power at least once a month for a few minutes (sometimes longer), it would give us enough time to save our work (.dwg, .pdf, .doc, etc) that was still open. I scheduled an automatic save of every 5-mins for the Acad.dwg's. But much work can be accomplished in 5-mins.
The worst thing about the APC back-up battery was when it was dead, could not buy a new replacement battery at that time.
Now I use two heavy (3000+ Joules) duty surge protectors in tandem for my home PC & & two for each of my two TV sets. That is 6-surge protectors. All peripheral items are also plugged in. Playing it safe. And now saving acad dwgs every 1-min.
I feel that a battery is not required as a surge protector by itself alone, only a strong surge protector does the job. I do not have ant intention to continue working or watching for the usual few mins that the power is out. If it is out for a day or longer, then I find other ways.

Posted by:

07 Mar 2019

I live in NJ also, and most of my neighbors have giant 50-KW generators permanently installed on the side of their homes. THey cost about $8,000. Being a do-it-yourselfer, I bought a $575 8 KW portable gerator, and installed a 50A power inlet jack on the side of my house that connects to the generator with a $40 extension cord. I have only used it a couple of times, but it's nice to know that when the UPS starts running low, I can fire up the generator and keep the lights, tv, fridge, and furnace running through the outage. I can tell when the power comes back on because I can hear all my neighbors' generators shut off.

Posted by:

Jim K
07 Mar 2019

Follow up to my last post: If you want to do what I did, you also need a lockout kit for your breaker panel. It makes it so you cannot run the generator without disconnecting from the utility. This is very important for safety. Make sure you Follow the instructions with the lockout kit to protect yourself and the utility workers.

Posted by:

07 Mar 2019

I suppose we in the UK are more fortunate in that the majority of our local power system run underground, and our supply lies are effectively a version of the internet with multiple connections across the grid, so we are far less vulnerable to weather-related - and many other causes - power failures. We do get the occasional dropout, usually for no longer than a few minutes, and only very rarely does it extend into hours. My stepson is the only one who really suffers as there's no real backup for his online gaming on his PlayStation - and the cable box takes a few minutes to reboot. As almost all my critical computer work is done on a laptop, I have plenty of time in reserve. A UPS is not only overkill, but an expensive way to cope with a once in a century event.

Posted by:

Robert A.
07 Mar 2019

If one is unfortunate to live in an area with frequent power outages, it certainly would be wise to invest in a whole house generator. They're made by Generac/Honeywell and by Kohler Power Systems (a sister company to the plumbing fixture company), and others, and are available in sizes from about 5 KW, for a smaller house to keep the basic necessities alive - some house lights and circuits, a furnace, a garage door opener, a refrigerator and/or freezer, to over 150 KW, which can power just about everything electrical in the property- even on a home the size of the Biltmore Estate.

As for UPS boxes, they are worthwhile to have, even if one has a whole-house generator, as they can be connected to computers, modem/routers and other electronics that may need to be reset or reprogrammed once the utility power goes out and the 10 to 30 seconds it takes for the Generac to kick in and begin supplying the house with power. The smallest one available should be sufficient to keep sensitive electronics running.

Virtually all UPS units have replaceable lead-acid batteries that usually last about 4 to 6 years. Too often, UPS users will scrap out a UPS box not knowing that they can buy new batteries for about 60%, or more, of the cost of a complete new unit. Unfortunately, the replacement batteries aren't sold Best Buy, as they would rather just sell a new UPS box.

Replacement batteries can be found at
Amazon and eBay, but I've been lucky to have a Batteries+Bulbs store a few miles away, that sells replacement batteries of all kinds, from coin-type watch batteries to massive vehicle batteries, at a reasonable cost. The folks there know which batteries will fit your UPS box, and can often install the batteries while you wait (if it's not too busy, which it usually isn't). I've picked up several smaller capacity, supposedly dead UPS/surge protector combos at garage sales, for five bucks, replaced the batteries, for about $20 to $30, and plugged all my computing and entertainment gear in each room, into a re-batteried UPS unit for less than half the price of a new unit.

Posted by:

Greg C
09 Mar 2019

Many years ago I owned both Trip Lite and APC UPSs.
There was a distinct difference between these brands and one had an annoying design that limited its usefulness. As you know, battery capacity diminishes over time. One brand, unfortunately I cannot remember which one, would continue to function with a diminished battery, and would even function as a surge protector, with the battery removed.
The other brand COMPLETELY shut off when the battery weakened to a predetermined level and ultimately not allow the computer to start up at all, just gave a loud alarm noise. This alarm can come on even when the computer is shut off and is usually initiated when the power goes off. Imagine in the middle of the night when the power goes off and the UPS starts howling in a pitch black house.
Some people may want a UPS that will not start if there is only a little battery life left, and know when it is time to buy a new battery or UPS.
Others like myself, only need a minute or two of power to shut the system down, or just a few milliseconds of buffering during a utility system switching maneuver from one line to another, as frequently happens here. A weak battery is not a big issue for me.
Just be aware that there are different design strategies.

Posted by:

Gary SE Wisconsin
09 Mar 2019

I had a major disaster a few years ago with a regular (high THD, dirty power) generator. These generators are OK for power tools and incandescent lamps. I blew out a TV, a microwave, a frig and a few CFL bulbs. I guess these things did not like dirty power! I now have an inverter generator and have used it with no issues.

Posted by:

Kenny D
09 Mar 2019

I always go to ebay for replacement batteries. Mine costs about $18 w/ free shipping

Posted by:

10 Mar 2019

If you are going to use a computer on UPS, then you should have a set of earplugs on hand. The UPS will cry until power is restored or you shut it off.

Posted by:

06 Jan 2020

I have owned 3 of the large tower APC units and two failed prematurely. They wanted me to run all kinds of time consuming resets and tests and troubleshooting here, and while they WERE WILLING to work with me, I don't spend a lot of money on stuff expecting to have to work on it myself under warranty, especially with a bad back and crawling around. One unit they actually kindly replaced, and then THAT unit failed in under a year.

Oddly enough, the THIRD one is fine but it's got very high end low power draw audio gear connected to it (not power amps drawing KW) and not power hungry computers.

I ALSO had a 14 month old and JUST out of warranty expensive computer FIRE that destroyed it when my APC was hooked up to it, though I have NO honest idea if that was what caused it, but I do know it started at a SATA power plug into a SSD drive, after diagnosis.

As for me, no more APC purchases. Your mileage may vary, and they may be building them different now. Today is 1-6-2020 and this happened a couple years ago.

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