iPad "Not Charging" with 3m USB-dock-connector cable
I just bough two 3-meter (10ft) USB-dock-connector cables on eBay. When I connect the USB connector to an Apple 12W USB Power Adapter and plug the dock connector into my iPad 3, I get the "Not Charging" message next to the battery icon. The cable works fine with iPods and iPhones. The normal Apple 3m cable works fine. I know the message is caused by not supplying enough current from the charger, and that charging still takes place, just slowly, but how is this possible? It seems that the iPad 3 requires around 2 amps (10W/5V) of current to satisfy its power hunger. 12W would theoretically supple even more current (12W/5V=2.4A). So what could be causing this apparent "current deficit"? Certainly a 10m wire could not have enough resistance to cause such a large current drop. This is DC so there can be no impedance issues. I doubt the soldering is so sloppy that the joints would have a high resistance but you never know… I have two such cables and both display the same behavior. I can't measure anything in the dock connector with a VOM because the opening and the pins are too small. What are some other possibilities that would reduce the current so much?
I was able to ring out the +5V (pin 1) and GND (pin 4) pins of the USB connector of both 3m cables and I found that the GND pin is NOT connected to the outer grounding shell of the connector like it is on the official Apple cable so that definitely is a problem. It means the USB +5V is floating and USB GND is not tied in with other GND pins. Geeze…
Apple dock connector pinouts: