Example: http://leicaphilia.com/wp-content/uploads/2014/05/BP-M3-5414...
I just worry about scratches though because I always sell my phones when I'm done with them.
Used to be I could just gift to my relatives, but they're pretty happy with their iPhone5's.
I had to get an external usb battery but only use that when I know I'll be busy a full day with more than usual usage (which is still quite a bit). Example being a full day of work (commute in and out) plus a sportsball game at night or similar where I'm seriously out all day.