Here’s another cute gadget, shown to us in the NY Times Gadgetwise blog: Size AA rechargeable batteries with built-in USB plugs, so you can plug the batteries directly into your computer to charge them. And here they are on Amazon.

They’re very cute. Only, they have several problems, some of which are pointed out in the user reviews on Amazon:

1. The USB plugs are on the flimsy side. Amazon users say they break easily.
2. They’re bulky and awkward as USB devices, and you’ll often not be able to fit two of them into two adjacent USB sockets.
3. Because the plug takes up some of the bulk of the battery, the battery itself has something shy of 2/3 the capacity of a typical AA.
4. You pay a lot for the novelty: it costs a great deal more than other rechargeable batteries.

It’s interesting how many of the favourable reviews, including the one in the Times, downplay the drawbacks, saying that they’re worth it because they’re rechargeable... ignoring that other kinds of rechargeable AA batteries are higher capacity, more reliable, and cheaper.

Amazon is selling these at two for nearly $20. For about $20 (including shipping), you can get a USB charger and four batteries. And then a pack of four more batteries costs $10. These guys just aren’t worth the cost.

Also, before you count on charging your batteries with your computer, remember that it can take several hours to get a full charge, and most computers don’t power the USB ports unless the computer is running. So you might have to leave your laptop running overnight in order to charge the batteries, regardless of which USB solution you go for.

You’re probably best off with something like this, a compact charger that packs easily, plugs into a wall socket, and works on both 110V and 240V power, so you can bring it with you anywhere.