"Universal" laptop power supplies - aren't.

If you travel, and use a laptop in business, you've probably made the mistake of leaving the power supply in your hotel room when you went off to the conference or event - or whatever. And, an hour later (or four, if you've got a newer unit), you realized that you were running really low on battery - and had no way to fix it. And that probably gave you the urge to get a spare power supply so that you'd presumably still have one in the bag with the unit.

It's a good plan. If you do it, though, I have to recommend getting one of the types that is made specifically for your model and make, not a universal one. There's a hidden reason why this is important for some laptops, particularly those from Dell. The computer and power supply trade information on many models; if the power supply doesn't identify itself to the laptop as being The Right Kind, the laptop will either refuse to charge the battery, or go into low-power mode (i.e., run dead slow with a dim screen), or both. Yes, you'll be able to run the system - sort of. No, you won't be able to use it as well as you expect.

I discovered this after having picked up a Targus universal power supply a while back. I'd made the mistake noted above - and remembered the small black velvet bag that had lain ignored in the bottom of the side pocket for a year or more. Grinning widely, I pulled it out, selected the appropriate tip (that's another gotcha point; see below), and hooked it up. And the laptop immediately went from normal battery mode (one step down in speed, two steps down in screen brightness from running on AC) to Super Power Saver Mode - screen at minimum brightness, CPU running at the *lowest* speed that the architecture would support - which was about 1/3 of its normal rate. And the battery wouldn't charge. It wasn't a case of insufficient capacity from the Targus side - the voltage and wattage ratings were identical. It was merely the fact that the Dell laptop didn't see a power source that identified itself properly, so it went to worst-case-scenario mode.

Can you say "Next to useless"?

Anyway, after an afternoon of Running Dead Slow, I made doubly sure not to repeat that error the following day, and made a mental note to pick up a spare of the right kind of power supply ASAP. If you've priced the ones from the laptop manufacturers, you know that they are Not Cheap. We have a Goodwill Computer Store in my town, so some of them can be had for $17.95 there; they used to sell them for a lot less, until the word got out. Many can also be had in generic-label form from sellers on eBay and elsewhere for prices that range from $12 to $45 - all of which are cheaper than the MSRP I've seen for the "Universal" units from either Targus or Kensington. I haven't found a webpage that lists the laptops that are picky, so as far as I know, the only way to be sure that a given "universal" power supply will work with your system is try it - or buy a power supply that's known to be dedicated to your unit.

One last note - if you have a laptop that's known not to be picky about its power source, it's still essential to take the unit with you when shopping for a replacement. All of the "universal" units require an adapter plug to hook them up, and there are so many variations in the designs of the power plugs (even within a single laptop manufacturer's line) that it's pretty much hopeless to expect that you can select the right one from a list. You really do need to plug it in and make sure it works with YOUR laptop before you buy it. And don't be surprised if they charge you an extra $10 on top of the $70 list price of the power brick in the process; that's a fairly typical price for spare tips, and the one you need is probably not going to be included in the kit that comes with the unit - if they make one at all.