Uninterruptible power supplies (UPS) review

Beat the blackout blues with these battery backup units.
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Test results for 18 UPS priced from $99 to $366

You’ve just about completed putting the finishing touches on your digital family photo album, but haven’t saved your work, and then the worst happens… a blackout. The power is gone and with it all your painstaking work — gone, forever. It’s a scenario that’s sadly all too familiar to many PC users, but it’s one that won’t occur if you use an Uninterruptible Power Supply (UPS).

A UPS is a battery backup unit that plugs in between your computer and the wall socket. If the power to your computer is suddenly cut, or drops significantly even for a microsecond, a UPS will cut in instantly and automatically supply power from its built-in battery. You then have time to safely save your documents and shut down properly — usually from 5-15 minutes, depending on the size of the UPS.

But what if you’re not at your computer at the time? No problem. Many home UPS systems also come with power management software that does the job for you. Once the UPS detects a significant power sag (or a total dropout) it immediately triggers the management software to save your documents and shut down the computer properly.

Please note: this information was current as of April 2009 but is still a useful guide to today's market.

Spikes and surges too

Modern home UPS systems also provide protection against electricity spikes and surges that can damage circuitry. Usually, surge protection is provided on all sockets which have battery backup protection.

A UPS may also have one or more sockets that provide surge protection only. This is useful for attaching devices that don’t specifically need a battery backup, such as printers, scanners and other computer accessories.

You don’t have to be in a blackout-prone area to get the benefit of having a UPS. If you’ve ever noticed all the lights suddenly dimming momentarily, you’ve probably experienced a power sag — sometimes called a ‘brownout’. That may be all that’s needed to make your computer suddenly turn off without warning — and without saving.

What we tested

Home UPS units are relatively small and affordable. We tested 18 home UPS units to see how they compared, noting how much power they supplied plus the performance of their software and other features.

Home UPS units can vary considerably in capacity — and hence, price — and though they aren’t marketed in standard sizes we have divided the UPS devices in this test into two nominal classes for comparison: Under 700 Volt-Amps (VA), and 700VA and above. Note that although the model number is often indicative of the unit’s capacity, this isn’t always the case.

Models tested

Under 700VA

  • APC BE550-AZ (550VA)
  • Belkin F6S600auUSB( (600VA)
  • Eaton Powerware 3105 UPS( (500VA)
  • MGE Ellipse 600( (600VA)
  • Opti CS500B( (500VA)
  • Power Shield Defender PSD650( (650VA)
  • Powertech MP5200( (650VA)
  • PSS UPS Pro650( (600VA)
  • Repotec RPT 603AU( (600VA)
  • Upsonic PROffice 650 UPS( (650VA)

700VA and above

  • APC BE700-AZ( (700VA)
  • Eaton Powerware 5110 UPS( (700VA)
  • MGE Ellipse Max 850( (850VA)
  • Opti ES1000C( (1000VA)
  • Power Shield Defender PSD1200( (1200VA)
  • Powertech MP5206( (1500VA)
  • Repotec RPT 1000A( (1000VA)
  • Upsonic Domestic series DS800( (800VA)


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