If you got a Android or Iphone, and like all smartphones; the battery won't last more than eight hours.
When you go on long trips, I like to be prepared. I also like to listen to music, user web , video or game you need
external Power Bank Backup Battery You can buy but you can homemade it very cheap and very easy
In here I homemade Boosting 3V to 5V board with MC34063 ( You see it on google with Boosting MC34063 or buy it on EBay under $5