Just looking at some options for festival season as the lack of reception always drains my battery... was bad enough on a BlackBerry, now I've moved over to iPhone 5, I doubt I'll get 4 hours this summer. I took a Android Samsung thingy to Pitchfork Festival in Paris a few years ago and battery died by 10pm, at 4am I left the venue and attempted to use Google Maps to find my hotel... yeah, that was a fun drunken walk. Changed phones shortly after that trip.
Anyone bought any of these power-up battery sorts of things? Intrigued by the solar ones you see on Amazon for about a tenner but then I'm sure they won't work if it pisses it down.