... which means that, even though you weren't "using" your device, there were multiple search, connectivity and data apps running in the background while you were out on your walk, such as Bluetooth, Wi-Fi, navigation/location, time, weather, Internet access etc, and the path of your walk may have also caused your devicee to have to search for and switch among multiple cel towers to maintain voice and data connectivity. It wouldn't be fair to say that the drop in available charge you observed was due to extreme low temperature alone. The device was working the same as it would likely have been working on a more temperate day drawing current for normal stand-by and background operations, but in less than ideal temps. Still it IS certainly an interesting observation. I suspect it would still be more on such a cold day than on a more temperate day, but I wonder how much the charge would have dropped if all of the power robbing apps that we so rely on for near instant personal communications gratification these days were disabled? For example, my Motorola Droid can go four or more days between charges - IF I switch off inductive charging, Bluetooth, Wi-Fi, Google Maps, Wayz, time zone, weather report, Chrome, and e-mail. Airplane Mode gives about the same charge interval. If I just switch off Bluetooth and Wi-Fi I can still go three days. If everything is active it's about two. and if I am making a lot of calls, sending and receiving a lot of e-mails, opening attachments, doing Google searches, opening web-pages, downloading, etc., I may have to recharge again by the end of the day.