If you have, as I have "never done" joke there..... found yourself at the end of a long day and noticing the battery is honking at you........ and I say something really neat like "OMG, forgot to charge it last night".....
Then you go to Power Savings Mode and it is good for another day or three even.
All you do is sacrifice all of the neat crap that makes it a smart phone.
It drops back to 1x plain vanilla and it can coast along like that for days and days and more days...
I do something like that everyday but a bit differently.
I use Battery Doctor's switcher to turn OFF,
DATA, WIFI, SYNC, BLUETOOTH, ROTATION, GPS....
Without even having to mess with Power Savings Mode, it does the same thing.
The phone lasted more than 5 days with light use.
that is, I made my normal telco calls, and I sent the usual amount of text messages.
But, nothing else. No internet stuff, period....
The S5 is very flexible.... make it do what you want, when you want.
Today, I got roped into a really dumb class that I had no interest in at all. I kept the S5 turned on all day long surfing the net, reading up on world news. looking at YouTube stuff, etc.....
and the battery is still at 65%....