I think I was able to achieve 20-21 minutes all the time, but today, I almost lost my Mavic, and it only lasted just for about 13 minutes on a full charge! I was flying in a slightly windy situation on a beach, the battery level was dropping significantly. As soon as I was notified about the activation of the RTH due to Mavic's own estimation of the power consumption needed to return home, I obeyed. The only thing I did, I tried to keep him out of the ocean, to my surprise it landed by itself on a 10% charge (frankly I tried to stay out of the ocean). It was 3000 ft from me/home point, thus it never achieved the RTH mission. Spend 1 hour looking for it (the beach area was a bit flooded after the hurricane), frankly my Phantom and GPS helped me to locate it. It landed on a wild grass, with ocean water underneath it. Literary 2 inches down, and it would be all in salt water. It did pop me a message saying that the landing conditions are dangerous and that it'll hover within 0.5 meters altitude, I'd chosen to keep it there, as elsewhere was wet.
Lesson learned. Mavic Pro is a great drone, and I got it just last week. It's a pure miracle how good it is. I'd experience with Phantom 3 STD, 4K & Professional. Flown Phantoms on rainy and windy occasions, worked perfectly fine, handled all the bad weather like a boss. Mavic is a bit different. The one has to be cautious when flying far on a windy day. It can translate the signal from 12,000 ft for sure (that's how far it went today), but can it return safely home thereafter? After today, I wouldn't rely on Mavic's estimation as to how much time it has left to complete the RTH.
Regarding the battery life. My suggestion would be to keep the battery charged only if you're planning on flying it within the 3 days period. Second observation is the altitude. The higher you're climbing, the bigger wind-force Mavic is facing, thus more energy it consumes as a result. Speed is also an important factor. Motors in a full throttle cause the heat in a battery to accelerate, my observations shows it results in a lower flight time.
View attachment 22089[IMG]
https://uploads.tapatalk-cdn.com/20170923/5aef80d85c41bbdc4e84f569c2d8f5b6.jpg