I was doing some interior work on the boat this morning- ambient temperature 28. I put my cell phone on the navigation table with my lunch bag, and turned up the electric heater. It takes a good hour and a half to warm the cabin to the point where I can take off my jacket so I went about doing some light housekeeping and after a while decided to check for my emails. My phone which was at 100% charge 2 hours before when i left the house refused to stay on. It registered battery at 10%. When I plugged it in it came to life but only momentarily. A google search on Apple says the Iphone shuts down in very cold weather. The surface of the Navigation table must have been near 15* according to Apple. The phone is working fine now that its warm. I guess I will learn to keep in in my pocket. I've had it! I'm going to Fl!