What can I delete from my SD card?

[ruggb]

that isn't exactly the reason to format..........

As a card is written and wiped there are files that accumulate on card that aren’t visible reducing the size of the card. This is very small and not a noticeable amount. However, it takes less time to format then it is to delete all the media files so it’s a good way the wipe the card and start a clean slate.

There’s no good reason NOT to do it

That isn't exactly the reason to format........
When video files are deleted from a card, holes are left in the data on the card. (The index that keeps tract of where the files are). Some systems require that video is written contiguously, therefore these holes are only good for equal or smaller files. Larger files are written elsewhere. This effectively reduces the capacity of the card because these holes can't be used. If the system uses these holes by breaking up the file, it significantly reduces the write/read speed to the card.
Even if you delete ALL the files, there may still be unusable holes, reducing the card capacity.
Formatting cleans out this index to allow one after the other contiguous file writing/reading again.

 

[JeffCharger]

from my experience, I've become very careful with how I handle files from the SD card. I recommend only formatting the SD card in the bird. I tried renaming some files on the SD card on my PC and it resulted in some very odd camera/gimbal issues. I was able to track the problems back to the changes I made to the SD card on the PC. I found that deleting files from the SD card on the PC was fine. Any changes to the files or attributes of the files outside the bird caused very odd problems (that didn't at first appear to be caused by the SD at all - but they were).

I suggest copying the files you want off the SD card and then formatting in the bird. This has worked for me without exception since my incidents.