As this has been going on for years (mentioned in multiple forums, first "Discovered" with the I1 and P3 series) and is a Android interface implementation issue and not a DJI problem (that they are doing or can circumvent). It is just that Android uses a data connection that must be energized, in doing that they have a charge gate that is always open. It is a design issue of ALL Android. It cannot be shut off (In stock configuration for most all).
Apple does use "some" charge, but it is very low as compared to Android device due to device architecture and how it syncs data. From my observations, when DJI found a way to stop Apple completely from charge they inadvertently left the toggle on display in Go 4 even in Android. They subsequently removed the Android side toggle in later updates to avoid confusion. In other words when it was showing in the Apps and was toggled (Android) it didn't really work, and couldn't as it is inherent to Android's connection protocol.
So if you have Apple as I understand the latest news, DJI has pulled the toggle off the Fly App, too many people do not understand the issue as I have outlined and continue to blame DJI (As well as any other interface) IF I understand correctly, Apple devices have this system built into their devices in the iOS system, DJI just used a shortcut to that command and implemented it into the App. For those who use Apple products and understand them, you must have a certain level of charge to trigger the on screen charge indicator.
Old chargers (Non Apple) only provide 500ma or up to 1.0 amp (Old Android Chargers). These will not trigger the charge indicator even though Apple is still receiving a charge (Power off and it will still full charge your Apple). I suggest people look and see if they have their apple set up properly in their settings, Google "USB Restricted Mode" and adjust accordingly. Apple takes a 2.0 Amp and higher to show actual charge which the DJI controller will not supply...unless of course DJI found a way to full energize the USB to allow for such.
Also originally you couldn't have any other device plugged into USB ports or it would lock the data connection between controller and device. DJI worked out that issue and I believe now you can indeed use two ports on the controller simultaneously. One for controller to device and the other for a charging input such as a power bank. So you have that option...but know that both ports if implemented as I described will indeed supply power to the controller. So you want to have your devices fully charged at first then said power bank would try and charge thus reducing but not eliminating the issue.
One further thing, I am seeing chatter over the years posted that it is/may be possible to stop android device charge if the device is rooted, I haven't investigated that claim but would probably need to know the custom Rom command or any App that would do this. This thread shows the ignorance of the issue and how long it has been going on..The blaming of DJI is just ridiculous and unwarranted.
controller charging android phone...
Hope this clears things up???