How much can an Apple Watch help iPhone battery life? Quite a bit

While everyone's device usage habits are different, my iPhone 6 is now getting nearly though two days on a charge. What's changed? Adding an Apple Watch.
Written by Kevin Tofel, Contributor

After nearly three weeks of wearing an Apple Watch, I'm finally settling into a routine. And I've noticed a postive impact to my iPhone 6: Longer battery life.

I charge the watch each night and put it back on my wrist as soon as I wake up in the morning. During the day, I have a limited number of notifications pushed to the watch, I use it for messaging and email management. And I have a few key apps that I hit from time to time to check the weather, my calendar, package delivery details and my running activities.

Moving those actions from the phone to the wrist has noticeably extended how long my iPhone 6 runs on a single charge.

The way I use my phone, I never had a problem getting through single day with the iPhone. But I'd always charge it at night because the battery would typically be around the 20 percent capacity mark at day's end. Now, it's closer to 50 percent when I go to bed.

The only variable here is the addition of the Apple Watch. My usage habits on the phone haven't changed and I still take most of calls on it; I reserve voice activity on the watch to when I know it's going to be a short conversation that I don't mind having on speakerphone.

See also: One month with the Apple Watch: Pain, joy, and daily experiences | First Apple Watch software update arrives with fixes, more health tracking info

Here's one example of the difference: The battery usage on my iPhone after having it fully charged during lunch yesterday. I was able to easily go 1.5 days on the prior charge and at nighttime, I still had 78 percent of the battery life left over a nearly 11 hour usage span.


Given that the display is often the biggest battery eater of a handset, this change makes sense. And it's not technological magic, by any means. The potential battery boost is due to shifting the user interface and information.

Why? The more activities you push from a phone to a watch, the less time the phone's display is on. There is the added energy drain of getting that data moved between devices but with Bluetooth LE, it's not nearly as much as using the display.

Granted, your own experiences may not mirror mine. We all have different notifications that are important to us, for example. And you may rely on your phone for more apps than I do.

I tend to get most of my online activities from a Chromebook all day, while if I really want to immerse myself in apps or other content, I generally grab a tablet. Still, I use my iPhone enough that, until now, it needed a daily charge.

I'm not suggesting that if you want more iPhone run-time on a single charge that the best solution is to get an Apple Watch. There are plenty of better alternatives out there: iPhone cases with built-in batteries, for example, or small external power packs that fit in a pocket.

Still, I'm finding this extra battery life to be a nice bonus when adding a smartwatch to my iPhone.

Strangely, I didn't see this same behavior when using a Sony Smartwatch 3 with my Moto X; or at least not enough that it jumped out at me. Now that Google is pushing an Android Wear update, I'll go back and some additional testing to see if that Moto X can run as long as my iPhone 6.

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