Almost all Android phones allow you to carry spare batteries. I use Endomondo, a free sports tracker application. It is wonderful. It puts my route on a map, announces each mile split-time. Records time-per-mile, top speed, average speed, calories burned, how much water I need to drink (what a dumb thing to include, but Americans love that stuff) -- everything I could want. It can automatically upload to my facebook page. I can opt to let others see my routes and workouts if I want. It shows cumulative mileage month by month and total calories burned and equivalent in hamburgers consumed. Excellent app. I can turn my phone onto AIRPLANE MODE and keep the GPS on and use the app and it is very easy on the battery that way.