Hi everyone, I'm new here and need some help.
I want to put a dji air 3 unit on my rc plane, with a separate battery from the plane's.
I understood that it must be with a B.E.C or a step down module.
How to proceed, which battery to use, which B.EC/Step down is better and must be used.
I want to connect a connector to B.E.C / step down to the input and to the output to soder the power wires power and grownd from 03.
Please help me! 
Thank you!

the voltage range of the o3 unit is up to 26v, if you dont run higher cellcount than 6s battery, you could power the o3 with same source like the motor - direct batteryvoltage.

as dji digital fpv isnt that sensitive to noise, it might work well. for very clean power, you could add an lc-filter between o3 and battery

Andrei, did you ever find the answers to your question? I am starting into FPV and have the same questions!