I have been having a bit of battery drain with 8.1.2 and couldn't work out why it wasn't present when using an old iPhone 5 backup, but was when setting the phone up as new or after resetting all settings. I seem to have got to the bottom of it though and the problem lies with location services. The new iOS8 way of doing it allows app developers more control over when their apps use device location. In the settings you will see the permissions as being always/never/whilst using the app. Sadly it is up to the developer whether they include the 'whilst using the app' setting! So some apps only have 'always' and 'never' as options. Even if you haven't used an app for weeks and it is not in the recent apps tray, of if it has never ever been opened on a particular install of iOS, it can still use location services in the background if the app location setting is set to 'always'! There appears to be a bug in the iOS location settings too, because the grey/purple location icons do not light up next to these apps even if they have been using location services in the background. I experimented and toggled all the 'always' settings to 'never' on those apps that don't have a 'whilst using the app' setting and bingo, my battery life improved significantly. It's a shame that some of these apps are ones I consider to be keepers, such as TomTom and AroundMe. However, whilst location services is operating in this new and inappropriate manner, I will just have to toggle them on before using them and then switch them back off again.