I've got the same issue with my
Mavic 2. Its a few years old, and has done a lot of flights, it was one of the very first ones when it was released (I got mine two weeks after the release date). First mine would only charge to 99%, then 96%, now 94%. Doesn't matter what I do. Does this mean the controller battery in mine is dying? I just updated the firmware on the controller and drone, because I'm about to to do some 3d photogrammetry with Drone Deploy, and while it was updating everything (and plugged into my iPad mini, which charges it at the same time), the controller charge percentage was rapidly plummeting too. What is going on, I don't want it die mid flight when Im running an auto photo grid on drone deploy. Any advice for me please, anyone??