If you still want to see the time on your Apple Watch but have no need for its other features, consider putting it in Power Reserve mode to save a bit of battery life. When your watch is in this mode, all features are disabled save for the current time, which is displayed in green.
Settings > Device maintenance > Battery > Power saving mode: Off.
Turn off Power Reserve
These steps assume that your Apple Watch is currently displaying navigational directions, and that you would like it to stop.
Just like the iPhone, the Apple Watch can be turned off using the Side button. First, raise your wrist to wake the Apple Watch. Next, press and hold the Side button (the one below the Digital Crown). Here, you will see the “Power Off” and “Emergency SOS” sliders.
How to turn off Apple Watch
Hold down the Power button on the Apple Watch (this is the longer button on the side of the watch, underneath the rotating dial crown button) Slide right on “Power Reserve” to switch into and enable Power Reserve mode on Apple Watch.
For Maximum power saving mode:
You can save even more power by simply turning off the always-on display, and then just raising the Watch to wake it. To do so, open the Watch app on your iPhone, tap General > Display & Brightness, and then uncheck “Always On.”
Clean and dry the Digital Crown Turn off your Apple Watch and remove it from the charger. If you have a leather band, remove it from your Apple Watch. Hold the Digital Crown under lightly running, warm, fresh water from a faucet for 10 to 15 seconds.
I suggest that you leave your Apple Watch on the charger for at least 2 hours. It should start automatically during that time, once the battery is sufficiently charged.
Just how powerful is the Apple Watch's S1 system-on-chip? Well, according to iOS developer Steve Troughton-Smith, it's roughly equivalent to the A5 chip found in the iPhone 4S, iPhone 5, iPad 2, fifth-generation iPod touch and first-generation iPad mini – at least where graphics processing is concerned.