Does the built-in backup battery of DJI Dock 3 support charging the aircraft?

No.

Related Questions

Which drones are compatible with the DJI 65W Portable Charger?

How do I power off DJI Dock 3?

Turn off AC, then press and hold the multifunction button to power off the backup battery.

How do I power on the backup battery of DJI Dock 3?

Press the button to power the backup battery if no grid power; otherwise, it powers on automatically.