My husband is also an IT guy and the responses here has had his brain running in overdrive. We have an iMac with a 3.0 USB port, and I've always used it to charge my batteries and never had a problem with it. When my husband read the responses, he was bound and determined to call BS, but couldn't find enough info to back either scenerio. The only info he could find was for the 1.0 and 2.0 USB ports. He even called the customer support at Bloog to find more info, but he's pretty sure they were giving him wrong information. They claimed the pass through only puts out 5ma (not 500), which can't be right. And to make matters even weirder, my pass through doesn't work when I plug it into the USB wall adapter. I tried different ports and different adapters, and none of them worked. I thought I fried the pass through, but when I plugged it back into the computer, it worked. I don't know WTF is wrong with it, but it's staying in the box 'till I figure this out, lol.