Many devices will have their battery life listed with 'up to XX hours of battery life'.
This is the maximum battery life the battery can sustain and is often measured with the device on standby, as this is when the device is using the lowest level of power while still powered on.
Depending on your personal use of a device, it is very common to experience less than the maximum battery life.
A common example of this is how a smartwatch or fitness tracker may say 'up to 5 days battery life', but with use as well as common sync settings, the battery may last closer to 2 days.
Similarly, a smartphone might feature 'up to 15 hours' battery life - this is dependent on the settings and battery-intensive content such as videos games will reduce this battery period.
Rest assured, this is standard for many electronic devices, however, if you are concerned with the battery life of a device, please feel free to contact our Support Team for assistance.