extreme cold

Hi! I am planning to get me a phantom 4. Have had 5+hours on a phatom 3 and am really convinced. My main object for filming would be at work with huskies. I have been trying to search if its possible to turn off any ultrasound from the machine and I have got the idea that its related to the...

So i'm not really worried about my Phantom 3 freezing up but rather my iPhone 6 plus shutting off. Even in 25 degree weather my phone will go from 50% down to shutting down in a matter of 5 - 10 minutes. I have been searching for cases that will keep it warm but I am not having any luck...