30" ACD usb ports low power

Discussion in 'Mac Pro' started by rasputin666, Feb 3, 2014.

  1. rasputin666 macrumors member


    Mar 1, 2009
    Hello there---I have a nMP and a 30" ACD connected via the apple dual link adapter. i wanted to connect my iPhone and iPad docks to the 2 USB ports on the back of the ACD but the iPad will not charge, says not enough power to draw from USB port. iPhone 5s has no issues charging/syncing. iPad syncs but does NOT charge. I was thinking, can i unplug the USB cable from the dual link adapter from the nMP and plug that into a wall outlet? would that power the 2 USB ports better? more importantly, not damage my 30" ACD, may be old [2008] but still a awesome screen. anybody have a different work around without plugging into nMP?
  2. NOTNlCE macrumors 6502a


    Oct 11, 2013
    DMV Area
    Your issue lies within the current that the display's USB ports can carry. As shown HERE the USB ports on your Cinema Display will only carry 500 mA of current, enough to charge your iPhone, but not quite enough to charge your iPad. There have been many issues with this in the past, and the reason your nMP USB ports charge it fine is because they are USB 3 and carry more current. In short, I don't believe it's possible to charge your iPad through those ports. Check out that support article though, lots of good info there.

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