The thing that puzzles me the most is changing the order of plugging in the individual pieces of my Nexus 7 makes a difference. Everything connected and working on ground power. Then power comes back on at 10,000 and tablet is not charging. Unplug. Light goes green. Plug back in, green light goes off and no charging. So then unplug the cable from tablet. Plug in the adapter to the outlet. Next connect power cable to device, and now it's working. sUA plugs seem more finicky and location is terrible for the plug/unplug game.