The battery life on my Z5 Dual is far less impressive ever since the update to Marshmallow. After a relatively long wait for an update for what was a brand new phone when Marshmallow began going out, this is the latest in a line of disappointments where this phone is concerned for me. Admittedly, if Stamina mode is brought back then it may make things better. Whenever the Xperia line opts to make something more like a stock Google product, the phone just becomes cheaper and ever-more lacking.
Days before the update I could leave my data on more or less all day in the background. I could also listen to music for 2-3 hours, and record 5 minutes of video, or take around 20-30 photos with the screen at about mid-level brightness. By the time I'd get home the battery would still have a respectable near-30% left on it.
Since the update, the battery just does nothing but decline. I did a 40 minute commute yesterday, with the data off (except for a brief check of my bank account) and the screen brightness slightly reduced. All the phone was used for was music. By the time I arrived at my destination the battery was down to 84%. Without any use again until going home, when it was again used for music for about 40 minutes and nothing else, the battery was down to 27%.
Today was even worse. The phone was used for music in a car journey this morning, the brightness almost all the way down and the data and wifi both off. It was at 95% when I left the house, and after just 20 minutes of playing music and doing nothing else the battery was down to 80%. I turned the phone off as I needed to use it later. Another half hour or so of music later in the day and it was down to 68%. I then used it to take about 40 photos and record about 4 minutes of video. It was down to 6% by the time I was home. Having kept an eye on it, it fell from 68% to 13% in an hour. In the past I have used the phone much more intensively, and the battery would likely not be below 50% back then. Let alone at the point where it urgently needs a charger.
I have a portable battery for the device. Pre-Marshmallow the device was capable of charging up the phone from 0-100% and then having enough excess to then charge the phone up again about another 15% or so. Today was its first use since the update, and it managed to get the phone from 6% to 47% before it ran out of charge.
Having checked that everything is in order, it is ridiculous just how much the battery is being depleted. And it's not a good sign... Android Lollipop caused the same issues to my Xperia Z1 which eventually ended up with a battery that would fall to 80% and then the phone would just switch off. These problems are a recurring pattern, and it seems no matter how much time is given to resolve any issues (I've had the phone for over half a year now) they recur just as frequently.
