Sony had to take out stamina mode some time ago because Google prohibited OEMs from messing with Doze mode which is more or less what Stamina mode. For those of you using other devices, it could be likened to your Power saving mode and Ultra Power Saving mode for others – like Samsung and Tecno.
Even with this, Sony found a way to bring back Stamina mode as they promised – I’m sure they found a work around or struck some kind of deal and came to a compromise with Google; either way, they brought stamina mode back but with a lot less customization. The stamina mode basically restricts background data and GPS etc to prolong battery life. But obviously, it let you do a lot more previously but according to the beta testers, many of these features have been removed – yes beta testers.
They released this update for Android 6.0.1 for the z2, z3 and z3 compact and it’s only available for select users. There is also an option for Ultra Stamina Mode which disables everything save a few crucial apps like call, SMS etc. The best part is that Stamina mode can run concurrently with Android’s doze without one interfering with the other. The question of whether this would make your battery last twice as long is still not confirmed but this should get you through a day without worries. Nothing can be confirmed for now until there is a general roll out of the feature – so stay tuned for updates.