"An LTE Apple Watch would require a separate monthly data plan, which is a barrier to buy-in," notes Tom's Hardware. "But being able to track workouts, receive text messages, make phone calls, download songs, get weather alerts and even use Apple Pay to buy stuff, all without carrying an iPhone in your pocket, could prove compelling for many current and would-be Apple Watch users."
The Apple Watch 3 will likely pack in the following improvements:
More Designs, First Circular Option Likely.
More Biometric Sensors
Either way, all models of the Apple Watch are likely to last about 18 hours based on mixed usage. That's not bad, but if you want to extend your Apple Watch battery life even longer, be sure to follow these tips.
1. Always upgrade to the latest Apple Watch software.
This is imperative and something many users fail to do. Increased battery life often comes about from tweaking software algorithms. Apple frequently adjusts these algorithms in software updates. If you want to have a longer Apple Watch battery life be sure to update the software on the device as soon as Apple releases it. To update the Apple Watch software open the Apple Watch companion app on your iPhone and go to My Watch>General>Software Update.
2. Keep your iPhone software up to date too.
This is completely antithetical advice to many people. How can updating your iPhone's software help the Apple Watch battery life? It's because the Apple Watch is a companion accessory to the iPhone and it requires the iPhone to act as a hub to function. The Apple Watch talks to the iPhone via Bluetooth and Wi-Fi. Most iOS software updates for the iPhone offer tweaks to these connectivity technologies, which makes them more power efficient. By making sure your iPhone's software is up to date you can ensure your Apple Watch and iPhone will communicate using the lowest battery drain possible. To keep your iPhone software up to date open the Settings app and go to General>Software Update.
3. Turn on Power Saving Mode to disable the heart rate sensor
The heart rate sensor is a great feature of the Apple Watch–one of the few sensors the Apple watch offers that an iPhone does not. But man, it's a battery hog. If you either don't care about using the heart rate function ever or just want to shut it off to save desperately needed battery life for the afternoon you can disable the heart rate sensors by enabling Power Saving Mode. To do so open the Apple Watch companion app on your iPhone and go to My Watch>Workout and turn on Power Saving Mode.
4. Keep Bluetooth turned on on your iPhone
If you disable Bluetooth on your iPhone, the only way your Apple Watch and iPhone can communicate is via Wi-Fi. And Wi-Fi is so much more power hungry than Bluetooth. That's why it’s always important to make sure Bluetooth on your iPhone is turned on.
5. Disable the Activate on Wrist Raise feature
The Apple Watch has an awesome feature that automatically wakes it and turns on the screen when you raise your wrist to look at the watch. It does this using the accelerometer as a prompt. But while this is handy and saves usage time, it can be a battery drain for those that are very active with their hands. For example, if you "talk with your hands", gesturing wildly, your Apple Watch will activate a lot because it thinks you want to look at it. To disable the Activate on Wrist Raise feature on the Apple Watch choose Settings>General and turn Activate on Wrist Raise off.
6. If you're a workout buff, consider getting a Bluetooth heart rate chest strap
As mentioned above, the Apple Watch has a heart rate sensor, which is awesome, but that sensor also is a huge battery drain, which is not awesome. If you're a big fitness buff and use the Apple Watch in your workouts a lot, you might want to consider springing for a dedicated Bluetooth heart rate chest strap. The Bluetooth strap will use less battery sending your heart rate info to the Apple Watch than the built-in Apple Watch Heart rate sensor will use on its own.
7. Keep notifications to a minimum
The Apple Watch is great because you can simply glance at your wrist to check out your latest notifications. But remember: every notification you receive is a drain on your battery. With that in mind, disable notifications for any apps that aren't critical. Do you really need to see a notification every time someone likes the cat video you posted on Facebook? We didn't think so.