[This has nothing to do with RC charging the phone!]
Now that we have a bunch of mini almost three years old. I think some of you may start having remote battery calibration issue like I do now. Basically the symptom is remote battery display shows for example 3 lights but when you have RC/phone connected to mini it starts to drain very quickly to show low RC battery warning (within minutes if it is serious). In fact it does that even when you have no phone connected. Then you press power button once to check battery it shows 3 lights again.
Someone on unofficial mavic forum investigated the issue and concluded repeated discharge of RC until it cannot power on followed by full recharge seems to fix the issue. This could be a bit damaging to the battery but I think uncalibrated battery gauge is more serious as a flight safety issue. I tried full discharge myself and I could get at least an hour extra by repeatly restarting the RC after it shutdown due to low battery. So I believe uncalibrated battery gauge is the issue. Aging battery can make it go out of calibration. Try this method before replacement or repair for your battery may not be that bad actually... If it is still not fixed try physically resetting calibration with this suggestion in post #9. Follow disassembly instructions .
Update: Did this once. Same issue occured again. Will try some more.
2023 Sept update: Happened again, try empty battery again. Did not work again. Disconnecting battery.
2023 17 Sept udpate: Disassembled yesterday, left battery disconnected for 40min and muffled beeper btw. Fully charged remote and connecting to drone on bench for 1 hour it held 4 lights solid (20min to get one start flashing before). Test flight today appears pretty good. The battery is recalibrated! Might have to do this a year later but that is ok.
DJI Stephen Posted at 4-19 20:23
Hello there Guorium. Good day and thank you for sharing these interesting information your us. Again, thank you for your support and keep flying.
AP302 Posted at 4-17 23:23
Dude, Thank you so much!
Before i had wrong indicators on my Mavic Mini and drained in about 30min
But i get a solid 22 min on each led.
That is how it should be! A shame DJI made it this way. A user that is not very handy will probably be forced to pay for new remote or buy new drone when what they have is perfectly fixable and fine.