Around 2003, I purchased a 10 foot Belkin USB extension cable.  It has been awesome.  It also works flawlessly extending my Apple wall charger to my iPad.  It's just a 10 foot gray cable, with the name Belkin on it.  I ordered several more extenders with the Amazon brand to charge other Apple devices, and none of the deliver a full charge, for reasons I can't understand.  The iPads all say "Not Charging".  Though, not with my 2003 Belikin.  So I send the Amazon cables back and order 5 of these guys, which look exactly like the one I've had for years.  Yet somehow, none of these work either.  All say 'Not Charging'.  And indeed, they do not.  They charge when the iPads are off, but if you use them, the battery will drain while the device is plugged in, making these cables nearly worthless.  So what happened between 2003 and now?  Why is this old cable so much more versatile?