Why do some data cables that work fine for data transfers, not work when used for charging???? I had some problems recently with getting my ipad2 to charge. I was in good company, as I read dozens of posts about similar charging issues, ie the "Not Charging" message when charging from a pc USB port, and not being able to charge even when using the wall charger. I am aware now that : the ipad in fact DOES charge ( more accurately, trickle charge) from USB ports, even when is says Not Charging - it simply takes longer. as for the wall outlet, I am aware some chargers are 5W vs 10W, etc. but what really got me scratching my head was why the ipad supplied 10W charger was not working. I have at lesat three chargers and about half a dozen cables. They are all Made in China so lets not go there. In the end, I was "surprised' to learn that while all my cables work for USB transfers etc, only some of them work with for charging. As soon as I changed the cable, . .presto, the ipad charged up in really fast ; use another "working" cable - no charging. So I ask: 1) why do some white Apple data cables, that work fine for data transfers, not work when used for charging???? 2) can one identify the good from the bad other than trial and error?