I need to make my iphone 4s battery last 14 hours?

I'm going to a concert and would like to take photos, i will need to phone a taxi on the way back
and will be using my phone on the way up

how can i save battery?

Cut down on the number of programs that are running in the background. Turn the screen brightness down. And if you don't want to be disturbed shut it down! Even without shutting it down you should be able to get a 2-3 days out of it, if it's just on standby!

Get a charger case.

Turn off Wi-Fi and gps, turn off autmatic updates of face book, email, etc. Switch it to only use the 2g network if possible.

Turn on do not disturb and try some of these tips. They do work. Best luck.
http://www.zdnet.com/how-to-improve-your-iphones-battery-life-updated-for-ios7-7000014902/

http://bgr.com/2014/03/21/iphone-battery-life-tips-and-tricks/