I am new to digiscoping, and currently use an iphone and phonescope adapter. I was out glassing for whitetails last week and found that I couldn't have my phone out for more than 10 minutes before the cold crashed the battery. Does anyone have any tips for keeping the phone charged in the cold? I think I might try connecting a portable charger to it while digiscoping with the portable charger inside my coat to keep it warm. Has anyone done this? Does anyone have a better suggestion?