The 15 mins you mentioned first sounds abnormal for the Mavic 4 pro.
Your flight data will probably find the reason for it.
Can you give a little explanation for your new "carbon based batteries" ?
Here's some follow-up that I've been working on to show how DJI's "GPS Altitude" is derived from atmospheric pressure and can vary with the weather by +/-200 metres.
For some months, I ran some test flights with a Mavic 3 pro from a known...
Airdata should be showing exactly what the recorded flight data has.
If it shows a 9 minute flight, then the recorded data for that flight is only 9 minutes long.
If signal was lost and later recovered, there would be another flight record for...