A few years ago, the only place you would see an uninterruptible power supply (UPS) was on a server. Many companies and institutions couldn’t afford to have their server being abruptly shut down by the weather, or when other issues were wreaking havoc with the power company. A UPS, while not terribly cheap, was an effective solution to deal with minor power outages.

In recent years, the price of a basic UPS has dropped significantly. What used to cost hundreds of dollars is now available for under $100, and sometimes even in the $15-50 range. Even if you’re not plagued by continuing power issues, it might make sense for you to buy one of these devices.

First, I’ll state the obvious. If it hasn’t happened to you yet, it most certainly will at some point… you’re working on the computer, be it typing an email, creating an article, writing an essay, in the middle of an online purchase, or doing some other task, and the power goes out. If you’re lucky, only minutes of your time were lost. If you’re unlucky, you may have just lost hours of work. A UPS will of course keep your computer running for a few minutes, which will usually give you time to finish whatever you’re doing, and (if the power hasn’t come up by the end) safely shut down the computer before the battery in the UPS runs out.

The next reason for buying a UPS isn’t so obvious. Power fluctuations can harm your computer. In the case where the power just flat out quits, you’re usually fine (assuming you don’t end up with file corruption). Where damage can occur though is when the power doesn’t die, and instead you’re presented with a voltage spike or a voltage sag.

A voltage spike is where voltage along the main power line is higher than it should be. Usually a spike is very short in duration and only occurs for a second or so, but any longer and the MOV’s (Metal Oxide Varistors) in most power bars will die, and the extra current will pass right along to your computer. A UPS will usually switch to battery power when it detects high voltage, and will keep long term high voltage from damaging the computer.

A voltage sag is where voltage along the main power line is lower than what it should be. How could low power hurt the computer? To provide the components in the computer with the wattage they require, the power supply in the computer expects to be fed a certain amount of AC voltage. When those needs aren’t met, undue stress is put on the power supply, similar to what happens when you use an underrated power supply. A UPS will treat low-power conditions the same as no-power, and will switch to battery backup.

With the low price of a UPS made for typical consumer needs, the question isn’t “why should you have one?”, but “why wouldn’t you have one?” Your computer probably cost more than a few hundred dollars, so protect that investment. You might even find it paying for itself in saved hours the next time the weather downs a power line.