One of the new features of iOS 9 is the possibility to monitor the battery of the Apple Watch through the iPhone Notification Center, through a widget. Let's agree that you will hardly use this feature when the watch is on your wrist, after all, it is much easier to see this information on the device itself.
However, the story changes, for example, if the clock is charging on your nightstand and you want to know if the battery is already sufficiently charged to leave the house. It turns out that Apple has not yet implemented a way to do the reverse: monitor the iPhone battery by Watch.
This makes a lot of sense when the phone is in your pocket or, as in the case described above, recharging somewhere "far" from you. what the app enters Power.
You can check how the iPhone battery is by the watch in two ways: by opening the app itself or by activating the "Summaries" option. This way, just slide your finger on the clock screen (from bottom to top) and the information will be there, updated in real time.