I’ve noticed that I’ve had a full battery for quite some time now. Do the Mavic 3 batteries have an auto discharge feature like other DJI drones?

Yes they have!  
9 days after fully charged, discharge begins...

frankymusik Posted at 1-15 09:05
Yes they have!  
9 days after fully charged, discharge begins...

They don't at the moment. I have 2 batteries left after my drone took off and checked them this morning and they are still full 4 LED's on and its been way more than 9 days since my drone disappeared. When my drone was still here I would put a battery on say after 12 or 13 days and it would be sitting at 96%, the auto discharge function does not seem to be working so better to leave it stored at 60%.

I get concerned about leaving any of my drone batteries fully charged for more than 24hrs, & with the Mavic 3 batteries costing £179 GBP I won't risk damaging them so I will just switch them on and leave them idling in the room for around 30-60 min, this will take a nice chunk out of the SOC just enough to bring them down enough until weather permits me to take them to 50-60%

My observation is after sitting for 3 days, a fully charged pack will still have  all its 4  leds displaying solid green, however, it'll only be showing as 95-96% on the FLY app.

I also see not auto discharge working, I had drone sitting for around one week and battery didn't discharged. Probably bug in firmware?

It’s documented in the manual that the battery will discharge to 96% after 3 days and then down to 60% after 9.

Pressing the button to check the batteries will reset the timer. So if you check them after 7 days then it will be 9 days before the discharge cycle begins again.

4 LEDs is the correct display for batteries at 96%

Mine discharges fine after a week or so

I have also noted mine discharged after ~ 2 weeks. I went to fly one day after not flying for a while and all my batteries were 2 green lights, when I had previously charged them all up and stored them in my bag. As Buzzyone says above though, if you press the button on the battery at any point before the discharge begins, you will reset the timer. This is likely why some are not seeing discharging occur.