The battery life on the new i5 has been pretty amazing for me so as long as you arent slamming it with downloads and surfing the web all day, you should be fine. If you are still worried though, I would recommend have an extra charging cable with you at your place of employment or wherever you are worried about it dying on you. Also, there are a number of wireless charging options that will accept any type of USB plug. You could take something like that around with you and just plug the USB charge cable into in when needed. All in all, I dont think you have anything to worry about.