You were flying 14,500 feet away from home, and the aircraft is trying to calculate how much power it will need to get the aircraft safely back to the home point. Even though the battery was at 63%, you are way too far out, that is nearly 2 3/4 miles,  and if you encountered head-winds, you would not make it back.

If you have to ask this question, then you would be advised to read the manual thoroughly, as it is a basic principle of how the aircraft operates.

but why does it go green again after awhile doesn't seem right

azpholt Posted at 2016-7-11 10:25
but why does it go green again after awhile doesn't seem right

Because at that stage you are on your way back, and it does the calculations all over again, and figures it can safely get back home. BTW, i edited my previous post to make it more explanatory.

thanks that makes more since its doing that to get home

Pay attention to the "H" on your battery life bar, the bar that is red,yellow and green with the timer on it. The farther away you go, the closer the H slides to the timer. Once the timer Green hits the H, the software knows based on time and distance, that it needs to start heading back in order to have enough battery life to make it under ideal conditions. The closer it gets back to you the H starts to slide away from the timer because it now knows that it is close to home and has some spare battery left. It is pretty smart, but not 100% accurate. If you have a headwind and your quad has to fight the wind to get back, it is going to use a lot more battery coming back than it did going out, so you might run out of battery and it might auto land right where it is at.  

Geebax's idea is correct. It is calculating in realtime.