Backup battery gives you time to save data

For years, I've been extolling the virtues of backups.

Yet you'd think I had never talked about the subject when I get someone's plea for help.

"Did you make a backup?" I'll ask.

"No," they'll say. "... I have been meaning to do so, but I just never got around to making one. So can you help me now?"

All I can say is that you should prepare for the worst.

Let me introduce you to the top-of-the-line power backup from APC (www.apc.com). The device that keeps a computer running when the power fails is a sophisticated battery device called an uninterruptible power supply, or UPS.

A UPS is simple to use. You plug it into the wall and plug your computer and devices that are critical to the computer's operation into the UPS. When the power goes out, the battery in the UPS continues to supply power, and that's pretty much it.

There are a few things to consider before buying one, however.

You need to determine how much power your computer system draws. Check the back of each device — computer, screen, external hard drive, routers and so on — for a label that tells you how many amps it draws.

When you get all the amp values, add them up and multiply that number by 120, which is the number of volts. The answer to the equation is the VA (volt-ampere) rating for your system.

Use that figure to choose a UPS that is right for your computing needs. Based upon that formula, expect the UPS to supply about five minutes of power if it is close to the computed VA rating. For most people, five minutes is all they need because the idea is to have time for a proper shutdown, not to keep a computer running indefinitely.

The biggest offering from APC in their personal-computer and workstation class is the Back-UPS RS, which comes with a whopping 1,500-VA rating. The product has a tower configuration that offers 865 watts to keep a computer system purring. It has all the usual bells and whistles, including audible alarms, LED status indicators, self-testing, a user-replaceable battery and software that will perform unattended shutdowns.

But the feature I like most about the RS is that you can expand it by adding a companion battery to the unit.

The Back-UPS RS/XS 1500VA 24V battery pack looks much like the main RS unit and is designed to stand alongside the UPS.

The pack even comes with an extension piece that expands the foot stand to accommodate both the units together. The pack easily plugs into the main UPS via a short extension plug.

Together, the UPS and the pack extend the power duration. The length of that duration is dependent on the VA rating of your computer system. But it is nice to know that you have the option of extending the power duration of this UPS if you decide to add equipment to your system.

Peripherals such as printers and scanners do not need to be on the UPS. Laser printers are notorious about how much power they can drain — a typical laser printer draws 15 amps. Besides, if the power fails and the printer or scanner stops, you haven't lost anything because you can always rescan or reprint whenever power is restored.

However, a UPS usually offers surge suppression, and it's nice to be able to plug in all of your devices if the UPS offers surge-protection-only outlets that supply no backup power. The APC model offers two of those as well as surge protection for telephone lines and Ethernet cables for network devices.

The Back-UPS RS 1,500-VA unit sells for $249.99 and the companion battery for $149.99. The UPS comes with software for both Windows and Macintosh.