Hi!
No way to prevent Android smartphone from draining and discharging battery of the Radio Controller?
DJI should do something to solve this very annoying issue.

+1 to that!

Some users suggest us allowing the charging function because they are worried about the low power of the mobile device.
It has pros and cons. We will also forward this to our engineers.  

I've had my Mavic for about a week and was having this same problem on my S8, so I contacted support via chat for help. After a couple of hours trying various suggestions from the support person, she finally said I should return the unit for a replacement. After reading this I see that replacing the unit will not fix the problem. I used an iPad from the vendor I bought it from and and it did not charge the iPad. I am correct in saying Android devices will draw power from the RC and Apple devices will not?

Shane6 Posted at 2017-9-15 22:07
I've had my Mavic for about a week and was having this same problem on my S8, so I contacted support via chat for help. After a couple of hours trying various suggestions from the support person, she finally said I should return the unit for a replacement. After reading this I see that replacing the unit will not fix the problem. I used an iPad from the vendor I bought it from and and it did not charge the iPad. I am correct in saying Android devices will draw power from the RC and Apple devices will not?

Yes, for Android device, it would be charged when it is connecting to the RC, but an iOS device will not. If this is your case, you don't need to send it in.

There are a few topics on this forum about this "problem"...  a way to solve it is to connect device to bottom USB port and connect a powerbank to the side USB-port of the RC... Some employee of DJI said not to do this because it would damage the RC but I know few people do use a powerbank to charge RC during flight.

Touch the Notification Tray and you can change it to Data Transfer mode and it won't do that.

Thanks rolling56. I have tried that, but it keeps reverting back to charge phone.

Mari Posted at 2017-9-16 10:59
There are a few topics on this forum about this "problem"...  a way to solve it is to connect device to bottom USB port and connect a powerbank to the side USB-port of the RC... Some employee of DJI said not to do this because it would damage the RC but I know few people do use a powerbank to charge RC during flight.

I'm one of those few people and have not had a problem yet.
controller stays at 100% and tablet maintains + 80% easily for more than an hour.
This is new hearing that (someone) from dji says not, but does not surprise me.
If I have a problem it will be on me but I feel good knowing I don't have to worry about controller or interface battery power when i'm flying.