How to buy the right UPS

The most important part, as Tim “The Toolman” Taylor would say, is power. You need to calculate how much power you need so that you can make the right choice. UPS power is expressed in volt-amps, or VA – most UPS will be labeled with a VA Rating to help you find the right one. Don’t worry, we’re not getting into much electrical engineering here, we’ll keep it simple.

Calculate your power needs

Instead of trying to figure out the volt-amps rating for every single device in your PC and adding them up, let’s just play it safe and assume that the maximum power you’d need for your PC is the volt-amps that the power supply in your PC needs. Turn off the PC and take the cover off so that you can see the power supply. Look for the sticker with the specs and find the volt and amp rating, write them down and multiply them. Now look on the back of your monitor for the same data, write it down and multiply it. Now add the two products and you’ll have a good number to work with.

For example, if you have a 115 volt/2.5 amp power supply, the VA rating would be 115 * 2.5 = 287.5.
Adding to that the monitors VA rating of e.g. 240, you would need a UPS with a VA rating of at least 287.5 + 240 = 527.5.

Alternatively, you could just add the maximum power (in watts) of the power supply and the monitor, e.g. 250 W power supply and 140 W monitor, and multiply it with a conversion factor of 1.4 to get an approximate VA rating of (250 + 140) * 1.4 = 546.

Either method tells you that you should be looking for a UPS with a VA rating of 550 or higher.

Additional features to look for

The next thing you should consider is how many outlets do you need to be battery backed-up and how many surge-protected. As a bare minimum, I would recommend 2 battery backed-up (for the monitor and the computer) and 2 surge-protected (for your printer and speakers) outlets.

Also be sure to get a UPS that has a user-replaceable battery. The battery in a UPS lasts several years, but eventually will need to be replaced. It is a lot easier to just order the replacement battery, have it shipped to you and plug it in yourself, than having to ship the UPS to the factory for the replacement and be without protection in the meantime.

Another important feature is the additional phone line surge-protector. You should have this because, as described earlier, a power surge can enter your PC through the phone line.

Make sure that the UPS has a decent status indicator. It should at least tell you whether the UPS is running on AC power or on battery. Additional features can be a building wiring fault check and power load on the UPS.

Some UPS’s offer an automatic shutdown feature. They come with a serial or USB cable that you connect to the PC and some software that you install. When you have a power failure, you can program the UPS to save all documents, close all applications, and shut down the PC gracefully in your absence. If you always turn your PC off when you are not at your desk, then this feature is probably not important to you. But if you leave your PC on 24/7, this is a very nice bonus feature.

Last but not least, any decent UPS comes with an equipment protection warranty. This means the manufacturer of the UPS claims to pay you up to a certain amount of money to replace your computer equipment if the UPS failed and your PC was damaged even though it was properly connected and secured by a UPS. While this is a nice feature, I have not spoken to a person yet that actually was in this situation and could shed some light on how their claim was handled. If you have been in this situation, I would like to hear from you – – and hear your experience.

If you are interested in a recommendation, check out my review at reviews/other/apcbupsp.html on the APC Back-UPS Pro 500 that I am currently using myself.


– Alex –

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