What happens to your Apple Watch when your iPhone runs out of juice

What happens to the Apple Watch after the iPhone it is paired with runs out of battery?

It may sound like an odd question, but a many Apple Watch owners are likely to find themselves in that spot at least once or twice.

For people who use their iPhone a lot during the day, perhaps for battery-sucking apps like mapping and video, there’s a very good chance their phone will run out of gas before their Watch (rated at 18 hours of battery life) does.

So what happens? The short answer (and there’s no long answer) is that any functionality on the Watch that relies on a network connection will cease working. The Watch has no cellular or Wi-Fi connection of its own. Instead, it connects to the web via the paired iPhone.

• If the phone dies you won’t be able to make or receive calls from your wrist.
• Communication apps like Facebook and Twitter wouldn’t be able to get updates, so they’d freeze in place.
• You couldn’t notifications of new emails or other messages.
• The Watch’s Sketch feature, which allows you to draw shapes on the screen and transmit them to a friend’s Watch, would stop working.
• The cute feature that lets you send your heartbeat to a friend would stop working, too.

But a lot of things on the Watch would continue working, which is a testament to the autonomy that’s already built into the new gadget, even in version one.

• You could still pay for stuff with Apple Pay using the Watch. Turns out that you need the iPhone to set up Apple Pay on the watch, but it’s unnecessary after that.
• The Watch can store up to 2GB of music, so it’s possible to listen to that music using Bluetooth headphones even if the phone is out of gas.
• Almost all of the exercise-related apps and functions would continue to work after the iPhone dies.
• The biometrics measurements enabled by the sensors on the back of the device, like the heartbeat monitor, would continue to work.
• You could still time your runs, but without the GPS radio in the paired phone, you couldn’t track and map your routes. An onboard GPS radio is one of the sacrifices Apple made to limit the Watch’s size; GPS radios suck a lot of battery and take up space.

Some people are a little disappointed that the first wave of smartwatches (culminating in the Apple Watch) rely on a paired phone to connect to the Web and to other devices.

But watches like the Samsung Gear S and the LG Watch Urbane LTE, both of which need no phone to place calls or connect to the web, point the way forward to a future where watches, once again, are completely autonomous.