Over the past six months, we’ve seen an increase in the number of device-agnostic battery packs marketed towards iPod owners: most notably, APC released the UPB10, which we currently use as a benchmark for iPhone and iPod battery performance, and many other companies such as JAVOedge have been selling similar alternatives that come with charging tips for cell phones, iPods, and more.

Late last year, Kensington joined the club with its Portable Power Pack for Mobile Devices ($60), another battery that trades on its device neutrality and simple design. The Power Pack is 2.25” wide by 4” tall and .37” deep, which makes it a little taller than the UPB10, but also narrower, and almost imperceptibly thinner. Like APC’s design, it is jet black except for company logos, battery indicator lights, and a power indicator button, and comes with a wall power adapter and a USB cable. Detach the cable from the power adapter and you can use it to charge mini-USB devices; for iPods and iPhones, you’ll need to supply the USB-to-Dock Connector cable yourself.
In all these regards, Kensington’s offering and APC’s are almost interchangeable.
Functionally, they have a lot in common, too. Press the power indicator button and the Power Pack lights up as many of its array of five blue LEDs as possible, letting you know in rough 20% increments how much of its power remains; APC instead uses a white light bar that glows less brilliantly as the battery’s depleted. They both have separate ports for power input and output, located on the same side, and neither one has any other special features; both put out USB-ready 5 Volts of power, with the APC at a 1.6 Amp max and the Kensington at 1.5 Amps.
The major difference between these two batteries, and where Kensington falls short by comparison with APC, is in power capacity. Whereas the UPB10 is a 10 Watt-Hour battery, with enough juice to power on and fully recharge a dead iPhone while still having some power left over, the Power Pack is a 7 Watt-Hour battery, which in our testing couldn’t fully recharge the iPhone once. iPods, however, are another story: without providing an iPod-by-iPod breakdown, Kensington promises up to 55 hours of extra iPod music play time and 14 hours of video play time, numbers that are basically meaningless at this stage because of the wildly varying power needs of different iPod models.
It suffices to say that the latest, most power efficient iPod nano and classic models will match or exceed those numbers, but older fourth- and fifth-generation iPods will struggle to reach them, and in any case, you won’t get as much power from the Power Pack as you would from the UPB10. Your results will also vary based on whether the iPod or iPhone is turned off while it’s connected to the battery, how much of its own battery remains, and whether the Power Pack was just topped off before connection or was sitting charged but idle for some time. We found that its battery lights were not always a reliable indicator of the actual juice left in thebattery.
Of course, Kensington’s justification for any difference in its performance relative to APC’s design would be simple: you pay $10 less for the Power Pack than for the $70 UPB10. And, as of the time of this review, you can find the Power Pack for $50. But then, the same is true of the UPB10: it can also be had for $50 or less online.