What is the Estimated max. standby time when enabling Ultra power saving mode?

Q : When enabling the Ultra power saving mode on Galaxy S5, Estimated max. standby time is displayed.
What’s this?

A : The maximum standby time shows the approximated amount of time remaining while the device is not being
used before the battery power runs out. This time may vary depending on your device settings, surrounding
environment, usage patterns, and actual device usage.