I’ve had issues with my iPhone 5 battery even before the iOS 7.1 update, and to be honest, I haven’t seen much of a difference after updating. There have been reports, however, that the iOS 7.1 update has caused significant battery drain on some units, and if you are affected by this “bug”, then here are some things you can do to fix it, courtesy of ZDNet.
Drain your battery.
Yup – the good old charge/discharge cycle. Allow your phone to go through several cycles even though you normally panic when your battery meter goes below 50%. You’ll survive, trust me; and your iPhone battery life might just improve.
If recalibrating your battery does not do a thing, then try resetting your phone. You have two choices: reset all settings or erase all the content. Try the former first, and if that still does not work, go all out and do a major reset. Obviously, before you do anything, back up your phone. The first option should not erase your data, but better safe than sorry!
Reinstall iOS 7.1.
If all else fails, do a reinstall; but this time, do it using iTunes and not over the air. To get the required file for this, and more explicit instructions, go here.
If your iPhone 5/5S battery just doesn’t satisfy you, you might want to get a Space Pack instead.
I have an Anker 15Ah battery in my backpack. It cost me less than €40,- and it recharges all my iDevices quite a few times before it has to be recharged itself from my 12W iPad charger. Best solution for me, and a *lot* cheaper than any battery case for iPhone, which is only good for one particular type of iPhone.