I am not disputing that fact as it could very well be an issue as well. I was just pointing out that the kensington pack is marginal at best for use as a power pack for our purposes, because without going into tolerances the kensington is only capable of 1.5amps of current draw and attys with a resistance of 3.2 ohms are going to want to pull 1.5625 amps and that is just the atty itself not including the resistance of the wiring to and from the atty and the resistance of the switch itself. Now as with all mass produced consumer products that are powered by Li-ion type batteries they are going to have an over current protection system on them, and I also would venture to say that there is also an over current protection on the voltage regulator circuit as well. What the tolerance level of this protection circuit is I have no clue as I don't have several here to test to get an average.
So can a Kensington powerpack work??
Yes, but you may have issues with it especially with atty's that have a lower resistance.
Is it an ideal pack to use??
No, since it's barely able to supply the current asked of it.
But right now we don't have much choice in the arena of usb power sources because most have a limit of 1amp and a few such as the kensington and the APC have a higher working current load.
R.F.