Battery Performance of Apple Watch in a Marathon

On Sunday, October 13, I ran the 2019 Chicago Marathon with an Apple Watch Series 5. This is a quick report on how well the watch battery performed.

TL;DR: Apple Watch Series 5 used only 50% battery over a full marathon distance, ran in 3:53:25.

⚡️ 50%   ⏱ 3:53:25   🏃‍♂️ 26.2 miles

Apple Watch Setup

• Series 5, 40mm in Titanium, with ‪watchOS 6.0.1‬
• Untethered — ran without tethered iPhone
• Cellular was Off
• Theater Mode was On‬
• Used the Workout app to track the run
• Power Saving Mode for the Workout app was Off
• No streaming audio — no music or podcast was played
• Water Lock was On

Total Run Duration

• 3 hours, 53 minutes, and 25 seconds

Total Run Distance

• 26.2 miles
• Distance tracked by the Workout app: 26.91 miles (See Notes below)

Battery Used: 50%

• Only 50% battery was used to run a full marathon
• 96% charge before start
• 46% charge at the finish

Battery at 96% before start

Battery at 46% after finish

Notes

• [7:15 AM] Kept the watch powered down until 15 minutes before the race officially started.
• [7:18 AM] On startup, battery was at 99%, I tapped on the Weather complication to refresh. That seemed to take too long (couple of minutes), so I immediately turned off WiFi and Cellular. Battery was now at 97%, probably from the network call trying to refresh weather.
• [7:20 AM] Turned On theater mode about 10 minutes before the race started. Bad idea, because it got tricky to wake up the watch display and start a workout with gloves on. Yes, that was me standing past the start line to start a workout 🤪. I usually put it in theater mode after starting a run. Never go off script during a race.
• [7:45 AM] I crossed the start line at 15 minutes past official start time. About 45K runners run the Chicago marathon every year, so the race is started in waves with different corrals of runners.
• [7:45 AM] The watch had been on now for about 30 minutes, and in theater mode for about 25 minutes, at 96%.
• With Power Saving Mode for the Workout app disabled, Apple Watch tracked the heart rate with the built-in sensor through out the run. But with Theater Mode On and Cellular Off, it essentially utilized 2 out of the 3 techniques that the Workout app's Power Saving Mode uses.
• Turning Theater Mode On disabled always-on display, and required tapping the screen everytime I wanted to view my running data (pace, distance, etc) in progress. I am used to this, because I have been using the same setup during my long runs for the past year, with Apple Watch Series 4.
• Workout app reported final distance to be 26.91 miles vs the official 26.2 miles. The additional distance of 0.71 miles is pretty normal for most of the tracking devices at such long-distance races due to reasons like erratic GPS signal around tall city buildings, or turns and curves adding up.

Marathon Ready

I have been training for and running marathons with Apple Watch since it launched in 2015. In total, I have run 6 marathons with Apple Watch(es), at least one marathon with every year’s model. There is no question on how well can the Apple Watch handle marathon training and racing. With only 50% battery utilization for an almost 4-hour marathon run, Apple Watch is an extremely versatile and powerful fitness device that no runner should ignore.

Here’s my marathon run in Tempo

2.6.2: A Tribute to the Marathon Distance

“ If you want to run, run a mile. If you want to experience a different life, run a marathon. ”

— Emil Zátopek

For many runners, marathon distance is sacred. To run a marathon, we can't fake through the training, and even when the training buildup goes perfectly, anything can happen on race day. A subtle variation from our plan on race day can have magnifying disastrous effects on our performance and experience. A lot of such critical variables are not even in our control to begin with. Running a marathon is a journey that changes us in so many ways. It’s such a unique lifetime experience that many of us find ourselves allured by the numbers 26.2 and 13.1 — the full and half marathon distance in miles.

iOS 13.1 instantly brought out the above intrigue in me. Without any specific plan around the release numbers, Tempo ended up being at 2.6.0 for iOS 13.0 launch. As iOS quickly went to 13.1, and Tempo was just .2 shy of 2.6.2, it felt like meant to be to ignore. So as a tribute to the marathon distance, Tempo has been updated to version 2.6.2 for iOS 13.1.✨

I wanted to do something simple and quick, but special for this one, so I picked up another version of dark mode theme. It was scrapped in favor of what we currently have as the default dark mode. After spending some time on it, to my surprise, the result is a beautiful new theme that we are calling Deep Blue. The name is still tentative for this one, we considered Blue Medal, Endurance Blue, Magic Blue, but for now Deep Blue it is. Please feel free to send your suggestions for the name.

There are also a couple of important bug fixes and enhancements, but I am really glad that we got this beautiful new dark mode theme in Deep Blue for this release. The fact that the theme was almost scrapped makes it special in its own way.

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Battery Improvements in Apple Watch Series 2

Summary:

The latest Apple Watch (Series 2) used only 46% battery for a 3 hours, 35 minutes run vs the first generation Apple Watch that drained most of the battery on a similar run last year. Both the watches are 38mm in size.

Some data from last year:

During a 20 mile run last year (9/19/15), Apple Watch (first generation) drained almost 99% battery.

Apple Watch (2015): Post 20 mile run. Battery at 1%.

The 20 mile run was in preparation for the Chicago marathon, and based on above data, I knew that Apple Watch won't last for the full marathon at my pace. On race day, I decided to not bring my iPhone so I could carry enough energy gels instead. This meant all of Apple Watch tracking was done using the built-in accelerometer. Surprisingly, I found Apple Watch to be way more reliable than a Garmin Forerunner that went erratic around tall city buildings. Unfortunately, with no paired phone, it also drained 100% battery in the first 16.3 miles.

For my spring 2016 marathon, I discovered power saving mode that disables heart rate sensor during workouts. I verified it during a 20 mile run and used it for the marathon. It worked great, and while the battery lasted for the entire race, I have no heart rate data from that run. It was a hot and humid day to run a marathon and heart rate data would had been an effective way to analyze how I faded off during the last 8 miles.

 

Same run with the new Apple Watch Series 2:

Last Saturday (9/17/16), I did the same run, a bit longer (21 miles), mostly along the same course, with Apple Watch Series 2. Here are some screenshots taken before, during and after the run,

Pre-run (9/17/16): Battery at 96%

At mile 19: Phone tuned off

Mile 20: Phone still off

Post-run: Battery at 48%

Run Summary

A quick side experiment:

This was the final long run of my training cycle for Chicago marathon, so I did not want to risk not bringing my phone along and possibly lose or have inaccurate data for it. While I still carried my phone, I decided it was safe enough to do a little experiment at mile 19 and turn off the phone. In the presence of a paired phone, Apple Watch relies on phone GPS reception for better signal and to conserve battery. So I was curious to see how the watch (specifically built-in GPS) would react, when a paired phone disappears in the midst of a run.

The transition was flawless. Apple Watch GPS took over seamlessly when the phone was turned off. This was verified with a course map generated from accurate location data for the whole run.

Not surprisingly, the built-in GPS did use more battery. In the last 20 minutes, battery availability dropped from 57% to 48%. That's 9% for 20 mins with built-in GPS vs 39% for the first 182 mins with a paired phone.

Again, this was mostly to test how well the watchOS and Workout app is built/tested for random GPS source switching. It's impressive that the watch GPS picked up without any glitch and it tracked the remaining run with no issues. In retrospect, considering I didn't want to mess with my data for this run, shutting the phone down was a risky move. I am glad that watchOS and iOS could pick up and sync nicely when the phone was back online.

Results – Battery improvements by numbers:

At mile 19, while still paired with a phone, the new Apple Watch had drained only 39% battery (that's about 41% for 20 miles *). This is substantial improvement over first generation Apple Watch that drained almost 95% battery for the same 20 mile run, done last year.

Mapping the above numbers to total running duration: first generation Apple Watch drained most of the battery for a 3 hours, 35 minutes run, where as the current Series 2 model needed only 46% (**) for the same 3 hours, 35 minutes run. That's over 7 hours of running time on one charge with still some battery power left. (Apple's official tech specs suggest 8 hours of workout from a full battery charge)

Even by including the variance caused due to the above side experiment, 48% for first 21 miles without power saving mode means I can run with the new Apple Watch Series 2 for a full 26.2 miles and still collect all the useful heart rate data.

This is great news for me as a runner and I am sure for many runners out there. If you are looking to buy a new running watch, I would highly recommend Apple Watch Series 2.

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* Battery was at 96% at start and 57% at mile 19. That's (96-57)/19 = 2.05% per mile.

** Battery drained for 182 minutes was (96-57=39%). That's about 46% for 215 minutes.