I returned my SP4 because I had a defective charger. The problem was the USB port, it couldnt charge any phone via micro usb and always lost the charging connection. Then after returning it and getting a new SP4 with a new charging brick, I have the same issue again. It isn't the phone, because I tried it with 3 so far, its not the micro usb cable because after a dozen nothing changed. I have a Surface pro 3 here with the old charger (as far as I can see, nothing changed), and no problems at all. Having it also with and without the SP4 connected. Do you have similar issues with the USB port of the charger, maybe I am unlucky to get the same defect twice, maybe its a quality control issue. Btw: I am using it in germany.