I don't know if anyone else has found the answer to this in the past year, but I now know what connector the Pro1X battery is compatible with. I had to disassemble my Pro1X for a non-battery related issue (bad display ribbon cable). It is a Huawei P9 connector. That may be used by other phones too, but that is the label on one of my charging boards. You can see this as port 24, on the green charging board, in the image in the second post in this thread. My other charging board, the blue Sunshine SS-909, also has this connector on the board labeled C1. It is the 3rd port from the bottom (