I have an S8 and my controller would be drained to near nothing while my S8 stayed 100% after one Mavic battery flight. After searching for solutions and fixes or how to root my phone to disable USB charging I stumbled upon a way to disable my USB charging on my unrooted S8 phone. This may not work for all android phones but it worked for me. All I had to do was punch up my phone pad and dial ##DATA# (##3282#). This opened a list of hidden settings to be viewed and/or edited. To edit these setting you will have to enter a six digit MLS PIN number. Mine was '000000' (default for some android phones from what I've read) otherwise you can obtain your MLS PIN number for your phone by contacting your carrier (which could be hit or miss depending on how nice they are). Once the MLS PIN number is entered you can go to the USB Charging setting in the list and disable it. My phone no longer charges from the controller and I was able to get all three of my Mavic battery flights in with 40% -45% battery left on controller and phone when done. You will need to re-enable the USB Charge setting before you charge your phone even if you charge wirelessly like I do. But it's so easy to do IF you have your MLS six digit PIN. Hope this helps some people.