So just recollecting the keynote. iOS 9 generally provides 1 extra hour of battery on iPhone and low power mode provides a further 3 hours of battery, totally a 4 hour battery life improvement (by the way the video "hidden features of iOS 9 is wrong in saying low power mode gives 1 extra). Anyway what I'm wondering is whether or not the 3 hour improvement happens when switching it on at 10% or having it on all the time? Anyone with ios9 tried low power mode ? I'm planning have my iPhone in low power mode nearly all the time because I have my iPad Air 2 for powerful stuff.