"What is the USB port power output?"에 답변This is more of a “caveat” posting! I tried to charge an “iHome” portable battery pack and it comes with a standard USB 2.0 micro connector cable. The Mid 2012 was upgraded to USB 3.0 ports, but what I did not realize is the iHome has a 5V/2A input requirement! I plugged in the charging cable, and immediate Black Screen!!! The MagSafe charging LED was off, the battery level button no longer showed anything. Pressing the power button for more than 10 seconds did not work! I pulled out my iFixit kit and took the back off, and used a spunger to disconnect the battery cable. Left disconnected for about 30 seconds, and then reconnected. At that point, the MBP turned back on for about 10 seconds. I put the back of the MBP in place, screwed in the screws, and I am now back to working condition. I really love that Apple put in some overdraw protection!!!