I have not used that "Y" cable before. I have always found on other cameras when I use the USB port for power it draws constantly on the battery even when the camera is sleeping. So, my solution has always been to use the fake battery method. One thing I have done when I had a issue like you are having is to make a 1/8" aluminum plate to go between the tripod plate and the camera. Then make a notch in it to allow for the wire.