I thought that I can charge my RC Pro with my mobile phone charger but it would only charge to about 47%. The first green light starts flashing quickly and the charging process stalls. I realized that the USB-C imput voltage must be between 12V to 15V to achieve full charge of the controller for which the supplied USB-A to USB-C cable needs to be used. I did not know that (RTFM applies here). Apparently it is not advisable to charge the RC Pro with the USB -C cable hardwired to the AC wall charger used for charging the batteries.