My money would be on the FitBit app. That is continually tracking your movements throughout the day in order to work out the number of calories burned off. Run trackers, TomTom and Pokemon Go are other apps that will kill a full battery in ninety minutes or less. Not worth running unless plugged into a high capacity external battery pack. The ones made by Anker and sold via Amazon are to be recommended, based on my personal experience. They don't explode and catch fire because they use standard metal cased 18650 batteries, have good capacity and are reasonably priced. Always handy to have one or two lying around for those extended days out or long country walks using GPS mapping.