Welcome from the Hampton Roads area of Virginia, USA. We have a Member's Map in the Upper Right of the Title Bar. Click on "Members" and then Click on "Member's Map…" Check it out and you might find some new flying friends...
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" ?