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Make your GPS watch last longer: Five techniques

Here is the situation:

1. The battery life of my GPS sport watch is, say, X hours.
2. The duration of my run, ride, or hike is expected to be greater than X.

This is unlikely to be the case for the longest of long training efforts, since even entry-level GPS watches last 8-10 hours. But in an ultra marathon, Ironman, expedition adventure race, 24-hour mountain bike ride, or multi-day backpacking trip, this situation is very possible, if not certain, especially for tougher courses and for slower participants.

So what am I to do? In this post, I will discuss five techniques to make a GPS watch last longer.

Since I am a longtime user of the Suunto Ambit2, the information here is most specific to the Ambit models. But the recommendations are relevant to other GPS watches, too, including those from Garmin and Polar.

My GPS watch was critically helpful during Run Rabbit Run 100 in September, especially early in the race, but still late in the race, too. So that my Suunto Ambit2 would last the duration of the race, which I expected to take about 20 hours, I tweaked the GPS frequency interval to 5 seconds from 1 second, which extended the estimated battery life to 24 from 16 hours.

My GPS watch was critically helpful during Run Rabbit Run 100 in September, especially early in the race, but still late in the race, too. So that my Suunto Ambit2 would last the duration of the race, which I expected to take about 20 hours, I tweaked the GPS frequency interval to 5 seconds from 1 second, which extended the estimated battery life to 24 from 16 hours.

Why should I care?

If my GPS watch will die before the end of my outing, it’s not necessarily critical that I take action. I may be indifferent to having incomplete data in my Strava profile, for example. And I might figure that, by the time my watch dies, I won’t need its quantitative data anyway — I’ll be relying on instinct to gauge my effort.

But, personally, I prefer that my watch remain useable. As an analytical (and anal) person, I like having a complete record for later analysis. More importantly:

In an ultra. I think that having the data — especially early on, but still late in the race, too — helps me to optimize my performance. A more experienced ultra runner may better know how they should feel at miles 70, 80, or 90, but I’m not there yet.

On a backpacking trip. My GPS watch is as helpful as my topographic maps when navigating, and generally more useful than my compass or handheld GPS unit. It helps me determine the distance to the next important landmark, the time to the next water source, the remaining vertical to a pass or summit, among other things. Also, when I return home, it’s useful to have a complete record of my track if I plan to repeat it or publicly share it.

A fastest known time (FKT) attempt would be another — albeit exceptional — instance in which I would want complete documentation.

Mark Austin's Garmin Forerunner 920XT died at around Mile 73 at Run Rabbit. Fourteen hours into the race, he was probably running more on feel anyway, but I'm sure he would have preferred to have a full record of his effort.

Mark Austin’s Garmin Forerunner 920XT died at around Mile 73 at Run Rabbit. Fourteen hours into the race, he was probably running more on feel anyway, but I’m sure he would have preferred to have a full record of his effort.

Make a GPS watch last longer!

Five things you can do:

1. Buy or upgrade to a better watch

Entry-level GPS watches like the Garmin Forerunner 25 cost $150-200 and last 8-10 hours. Top-of-the-line watches like the Suunto Ambit3 Peak cost $400-500 and can last 20-200 hours, depending on the GPS frequency interval.

Refer to the battery life comparison chart for GPS watches that I published last week.

If at least occasionally my adventures will be longer than the battery life of an entry-level watch, I might quickly overlook the premium cost of a higher-end model. The nicer build and enhanced features offer additional value, too.

2. Mid-flight watch exchange

If I have another GPS watch (or smartphone with an app) that I can swap, I have effectively doubled the duration for which I will have data. This is a clean and fast solution, but not without pitfalls:

  • It’s expensive, unless I borrow the second watch, or use an older watch that I held onto after upgrading to a newer model (which is lost resale money).
  • The data will be recorded as two separate efforts — like a Monday and Tuesday run — which will complicate post-race analysis unless the files are merged. Refer to the comments for links to some online tools that will do this.
  • Before the race, I will have to adjust the display fields and recording settings for two watches, which is a slight inconvenience.

3. Mid-flight recharge

On a backpacking trip, recharging my GPS watch is a no-brainer. I do it when I’m stopped — normally, in camp or at a long lunch break — and the weight penalty is minimal: the watch-specific power cable, plus a 3-oz Anker portable battery charger, which I use to recharge my smartphone-turned-GPS, too.

If I had to recharge my watch while moving, however, I would probably find another option. I have no interest in running, riding, or hiking — especially in a race environment or on semi-technical terrain — with a loosely attached wire dangling between my wristwatch and a charger tucked inside my pack or a pocket. Brian Lucido was forced into this situation during his FKT attempt on the Sierra High Route, and it sounded less than ideal.

During his FKT attempt on the Sierra High Route, Brian Lucido had to recharge his Garmin Epix twice per day. In a race environment or on semi-technical terrain, this technique is an annoyance, if not dangerous.

During his FKT attempt on the Sierra High Route, Brian Lucido had to recharge his Garmin Epix twice per day. In a race environment or on semi-technical terrain, this technique is an annoyance, if not dangerous.

WARNING. This technique may solve one problem (limited battery life) but it may encounter another: limited internal memory. My Suunto Ambit2, for example, can record about 25 hours of data at 1-second intervals. (This estimate is based on unofficial online sources; information from Suunto is hard to find.) If I try to record more data, the most recent data will overwrite the earliest data, thus defeating an objective in recharging the watch: to have a complete record of my outing.

Thankfully, with the Ambit there is an easy fix. In Movescount, I can change the recording setting to 10 seconds, from its default 1 second, which would create enough memory for about 250 hours of data.

If I'm concerned about overloading the internal memory of my Ambit, as would happen if I tried to record a 1-week backpacking trip at 1 second intervals, I can reduce the recording interval setting in Movescount.

If I’m concerned about overloading the internal memory of my Ambit, as would happen if I tried to record, say, a 1-week backpacking trip at 1 second intervals, I can reduce the recording interval setting in Movescount.

4. Change the GPS frequency

Obtaining its precise location (i.e. a fix, in latitude and longitude) via GPS orbital satellites is the primary power drain on a GPS watch. Other hardware like the display, barometer, accelerometer, and heart rate receiver consume relatively little battery.

Most commonly, a GPS watch is set to obtain a GPS fix (and record that data) every 1 second. This frequency is adjustable on some watches, however:

By increasing the GPS fix frequency, battery life is greatly extended. The aforementioned Garmin models last 50 hours in “UltraTrac” mode (60 seconds), versus the normal 20 hours, according to Garmin. However, there is a cost to a less frequent GPS fix: less accurate data. Read more about this tradeoff.

Personally, I have found that a 1- and 5-second interval is adequate for running, and that a 60-second interval is adequate for hiking. 60-second data of a run could be considerably inaccurate, as many twists and turns can go undetected between GPS fixes. In fact, in theory, if I ran at 7 minutes/mile pace around a 240-foot diameter circle, my watch would record zero distance, assuming that data from other hardware like the accelerometer and barometer/altimeter was not utilized.

On backpacking trips I use a 60-second GPS accuracy setting. The route data is sufficiently accurate, and battery life increases to 50 hours, which means I need to recharge the watch every 3-4 days.

On backpacking trips I use a 60-second GPS accuracy setting. The route data is sufficiently accurate, and battery life increases to 50 hours, which means I need to recharge the watch every 3-4 days.

5. Multi-sport modes

Among all the techniques mentioned, this is my favorite. The advantages:

  • One watch
  • One complete data record
  • No mid-race recharge
  • Maximum data accuracy, given the constraints of using just one watch without a recharge

I’m certain that it can be done with a Suunto Ambit, but less so with Garmin or Polar models. If you are more familiar with the advanced features of these models, please share.

In Movescount, I created three “Sport Modes,” and named them Ultra 1, Ultra 5, and Ultra 60. All of the settings are identical, except the GPS frequency:

  • Ultra 1: “Best” (1 second), at which the Ambit2 has estimated battery life of 16 hours
  • Ultra 5: “Good” (5 seconds), 24 hours
  • Ultra 60: “OK” (60 seconds), 50 hours
In Movescount, create two or three Sport Modes, with identical settings except the GPS accuracy.

In Movescount, create two or three Sport Modes, with identical settings except the GPS accuracy.

During a race, I can change between Sport Modes on-the-fly by holding down the upper-left “BACK LAP” button. I can change the Mode (and thus GPS frequency) based the remaining battery life or on my desire for accurate data.

For example, I could race for 14 hours in Ultra 1 mode, draining my battery to about 12 percent, then change it to Ultra 5 to eek out another 3 hours (17 hours cumulative), or to Ultra 60 for another 6 hours (20 hours cumulative). Fourteen hours deep in a race and closing in on the finish, I’m probably relying much more on instinct than watch data, so the accuracy is less important. At the finish, though, I still have a complete record of my effort.


Disclosure. This post contains affiliate links, whereby I receive a small commission for sales-generating referral traffic. There is no cost to readers (e.g. prices are the same), and it helps to support my efforts to develop great content.

17 Responses to Make your GPS watch last longer: Five techniques

  1. Joe Buettner November 8, 2015 at 10:14 pm #

    Great article, Andrew. I have been doing some research on gps watches and your article pinned it down for me. The Suunto Ampit 3 is my choice. My 2016 schedule is to do a section of Steve Ropers HSR and part of your HSBR and the CT this Summer. The watch would be a great addition with my current up to date maps. Thank you.

    • Andrew Skurka November 9, 2015 at 7:07 am #

      For backpacking, I would only recommend a watch that has the option of a 60-second GPS frequency. This interval offers sufficient accuracy, and it is key in extending battery life. The watches without the 60-sec interval are a non-starter for backpackers, IMHO: on a daily basis, you’d need to recharge the battery and download the track data.

      I can attest to the battery life estimates of the Suunto models (even after 2 years of near daily use, battery life of my Suunto Ambit2 is still slightly better than Suunto’s estimates), but not those from others. I feel like I’ve read that Garmin’s are very optimistic.

      In short, I would definitely recommend an Ambit. My Ambit2 has been awesome, and the Ambit3 should be even better.

  2. Derrick Spafford November 10, 2015 at 6:16 am #

    Good to see you gave the multi-sport mode option a try. I’ve always felt it’s a great, but underused method for ultra runners.

  3. Eli November 10, 2015 at 12:11 pm #

    Let’s say you had two GPX files from an event because you used two Ambit watches. You don’t think it would work to splice those together using a text editor? I am pretty sure it would. You’d just need to make sure the log file of one ends before the next one begins.

    But you’re right that owning two watches would be silly. But maybe you could pull it off at least once: buy a second watch, do your 16hr+ race using both watches, and then sell your old one after the race. I might like to do that for a 100 miler next September if the Ambit 4 is released by then if I am going to upgrade anyway (and sell my Ambit 2 after the race).

    • Andrew Skurka November 10, 2015 at 12:33 pm #

      If you could pull the original files off your Ambits, stitch them together, upload a single file back to one of the Ambits (so long as it has enough memory), and download it to Movescount, your suggestion might work. But I have yet to find a way to even download the files off the Ambit, never mind the rest of the tasks. Any computer whizzes have a suggestion?

  4. Cody Cunningham November 11, 2015 at 5:41 pm #

    I have used this to splice multiple .gpx files together into one file for Strava.

    http://www.davidgouveia.net/325-2/

    For 100s I have usually gone 310XT and then phone for the rest.

    • Andrew Skurka November 11, 2015 at 6:11 pm #

      Good tip.

      That tool combines GPX files, but would it carry over other data like HR and altitude?

    • Brian Lucido August 25, 2016 at 10:03 pm #

      On this topic, I’ve created a tool that does carry over HR data, altitude, etc. Moreover, it merges other file types besides GPX… You can combine TCX, and FIT. In fact, you can combine a FIT with a TCX or a TCX with a GPX, or a…… you get the point. If you want, you can have it upload directly to Strava. Here is the link to the web app:

      http://gotoes.org/strava/Combine_GPX_TCX_FIT_Files.php

  5. Sean November 15, 2015 at 4:53 pm #

    Hi Andrew,

    I’m kind of torn between looking at the Traverse and the Ambit3 peak. I’m not particularly concerned with the price difference since it’s to be a gift, and I’m looking mostly at a daily wear & backpacking watch, although I’m starting to get into running a little bit.

    The biggest draw to me with the peak is the 200 hour listed battery life in the economy mode. That’s… kind of incredible. The Traverse is half that battery life and seems to be more focused on… I’m not sure what. It sounds like it’s more focused on backpacking, it looks a little more stylish, and it’s got a few features I like (vibration alarm, the barometer is pretty cool, etc).

    I don’t know enough about these watches to really make a decision. Is there any input you could put in on the two?

    • Andrew Skurka November 15, 2015 at 5:03 pm #

      Funny, that’s how I feel about the Traverse, too. Until I get first-hand experience with one, I’ll be unclear about what it does or how it’s different than the Ambit watches.

      FWIW, I now use exclusively my Suunto Ambit2 (the predecessor of the Ambit3 Peak), including for all of my hiking and backpacking trips. There is nothing it can’t do that I wish it did. It’s critical, however, that you create display fields to your liking, via your online account in Movescount, which will then sync with your watch. I should write a post on this like I did for the ultra running displays and settings, since my preferred setup for hiking is very different.

      Go with the Ambit3 Peak. You won’t be disappointed.

      • Sean November 15, 2015 at 7:36 pm #

        Hi Andrew,

        Thanks for the feedback!

        I think you sold me on it. Everything I’ve seen from the traverse is that it’s a little less accurate (this might be fixed in firmware), and it’s not as robust. Which I’m okay with as long as it excels at what it does, but it looks like the ambit3 peak can do whatever the traverse does, with few exceptions.

        For a while I had an eye on the Fenix 3, but with 50 hours of battery life in it’s extended mode and the lack of bluetooth I really wasn’t that impressed.

        • Sean November 17, 2015 at 11:12 pm #

          Just got the Ambit3 Peak. It really is a nice watch. And I see what you mean about setting up the sports/modes exactly how you want them. The capabilities of the watch kind of remind me of an android phone. Just under the surface there is a bajillion options that you can bring up to the top layer exactly how you want them. You just have to know what you want.

          The app store is pretty cool too. And the programming language looks fairly straightforward.

          I’m looking forward to getting deeper into it. Thanks again!

  6. Frederic November 17, 2015 at 5:46 pm #

    Andrew,

    You state the following : “The data will be recorded as two separate efforts — like a Monday and Tuesday run — which will complicate post-race analysis; merging the files is not easy, or even possible.”
    Actually, I use the software Sporttracks and it has a function to merge as many activities you want. It will merge HR, temperature, elevation…etc). I use that to merge my different files when I run 100-milers (i use the Mid-flight watch exchange method)

    Check it out here :https://www.zonefivesoftware.com/sporttracks/
    Frederic

  7. Jeff January 3, 2016 at 11:14 pm #

    Hi Andrew,

    I been loving my Ambit 2 for the last 18 months but find planning routes on the Movescount website to be a bit tedious, since it uses Google and not some sort of topo map that shows trails and such.

    What are you using to plan your routes and syncing with your watch? I wish there was a way to simply click on a start and end point on a trail. Right now I’m going to the satellite view and trying to see the trail through the trees and clicking on what I can see.

    Jeff

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    […] 8 hour batter life. Uh-oh.” Last week Skurka wrote about which GPS watches last the longest. Here he discusses how to extend the battery life on your […]

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