Thanks to Zolly, I solved the RC-N3 battery drain

[bbteach]

A YouTuber named Zolly solved the problem of DJI controllers ( I my case the RC-N3 ) battery getting drained to keep Android phones charged. See his video here:

Using his trick I built this USB C wire:


I haven't put shrink tube on yet because I am still testing.

It is made up of the following components:
1 watt 15 volt Zener diode ( 1N4744A DO-41 ), WMYCONGCONG Latching Push Button Switch ( WGCD 85 ), AGOZ 6inch Right Angle USB C cable ( ASIN: B0B8TJM38V ).



Steps:

1. Strip back the outer and inner covering of the USB cable
2. Cut the RED wire
3. Solder the diode across the switch legs ( stripe on the phone end of the cable )
4. Solder the switch legs on to each end of the RED wire

Test results in the next post:

 

[bbteach]

Testing results:

Test setup:

• Start with RC-N3, phone and Neo batteries fully charged
• Turn on phone, RC-N3 controller and Neo ( in that order )
• Verify phone IS BEING CHARGED by the RC-N3
• Verify the Neo is streaming video to the phone
• Set a 15 minute timer and leave everything alone for 15 minutes

At the end of 15 minutes turned off the Neo and the RC-N3. Checked the phone charge level. As expected it was 100%. Turn off the phone.
Put the RC-N3 on charge power ( power supply was ONLY charging the RC-N3 ). Start a stopwatch.
It took 18 minutes for the RC-N3 lights to go out ( indicated it was fully charged ).

• Press the switch button on the custom USB cable
• Verify all batteries fully charged
• Start all 3 components
• Verify the phone is NOT being charged by the RC-N3 controller
• Leave the Neo streaming video to the phone for 15 minutes
• Shut off the Neo and the RC-N3
• Check the phone charge level ( 97% )
• Shut off the phone

At the end of 15 minutes and with all units powered off. Connect the RC-N3 to the power supply and time how long until all lights turn off.

Results:

• With the RC-N3 charging to phone it took 18 minutes to recharge the RC-N3
• With the RC-N3 NOT charging to phone it took 8 minutes to recharge to RC-N3
• 44% reduction in battery recharge time on the RC-N3 when it is NOT charging the phone

Over a longer period, the reduction in RC-N3 battery use may be even more pronounced.