What are the most important considerations when deciding which GPS sport watch to buy? Features, fit, and price — most definitely.
But don’t overlook battery life, especially if your workouts, competitions, or adventures often exceed the duration of a long workday, as is the case with ultra marathons, Ironmans, expedition adventure races, 24-hour mountain bike races, multi-day backpacking trips, and other long-distance activities. Even if you prefer shorter outings, a robust battery is still a perk: like a new cell phone, it will need to be recharged less often.
If your GPS watch battery dies before you’re done, at a minimum you’ll have an incomplete record of your effort. (And you know what they say — If it’s not on Strava, it didn’t happen.) But it could be worse: without access to data like pace, heart rate, distance, coordinates, or elevation, you may struggle to maximize your performance and/or to navigate.
In this post I discuss the factors that affect the battery life a GPS watch, and provide a battery life comparison chart for GPS watches. Skip to the comparison list.
Battery life basics
The power capacity of a battery is measured in ampere-hours, specifically milliampere-hours, or mAh. A battery with more mAh will last longer than one with less, all else being equal. For example, the Suunto Ambit2 features a 480 mAh battery whereas the Suunto Ambit2 S has a 240 mAh battery. Not surprisingly, the battery life of the Ambit2 is about twice that of the Ambit2 S: 16 hours versus 8 hours with a 1-second GPS recording interval.
But “all else being equal” is seldom the case, so mAh is not the sole determinant in the battery life of a GPS watch. For example, the Polar V800 has a 350 mAH battery, yet its battery life is about the same as the Suunto Ambit2. I don’t have a precise explanation, but no doubt it’s due to differences in hardware and software.
GPS recording intervals
The primary drain on the battery of a GPS watch is the recording of its precise geographic position (i.e. a “fix,” measured in latitude and longitude) via GPS, which requires communication with orbital satellites. Other hardware like the display, barometer, accelerometer, and heart rate receiver consume relatively little power.
The frequency at which a GPS fix is obtained — known as the GPS recording interval — is either fixed or adjustable, depending on the watch. All Suunto Ambit watches can be set to 1-, 5-, or 60-second intervals (“Best,” “Good,” “Okay”), for example. With longer intervals between GPS fixes, the battery lasts longer. For example, the Garmin Fenix 3 lasts 20 hours with a 1-second interval, but for 50 hours in “UltraTrac” mode (a 60-second interval).
A fixed, non-adjustable interval limits the ways in which the battery life can be extended, and — I would add — the watch’s applicability for long-distance efforts.
Unfortunately, as the GPS interval recording increases, the accuracy of the recorded data — e.g. route, pace, distance — decreases. For instance, when running at 7 minutes/mile pace, a watch will record its GPS location every 12, 63, and 754 feet when set to 1, 5, and 60-second intervals, respectively. During these longer durations between recordings, obviously there can be more undetected twists and turns. Data from other hardware can improve accuracy between the GPS fixes, but the watch will mostly assume a straight-line distance between recorded positions.
Battery life comparison of GPS sport watches
In the market for a GPS sport watch, and wanting to compare estimated battery life? The chart below is for you. Estimated battery life is based on manufacturer specs; the figures have not been independently verified.
What are your thoughts on the new Suunto Traverse Andrew? http://www.suunto.com/en-US/Sports-Watch-Collections/Suunto-Traverse-Collection/
I first saw the Traverse in an email when it came out, but I’m not entirely sure I understand what it does — or, really, what niche it fills in Suunto’s line. This synopsis tells you absolutely nothing:
“The Suunto Traverse is a GPS and Glonass watch designed for hikers and trekkers who want to explore new terrain and value simplicity.”
Based on the specs, it sounds like it’s an Ambit3 with more focus on navigation (e.g. download routes created in Movescount) and less focus on workout data like speed, pace, and HR, at least in its displays. I don’t think the Core, formerly the go-to for hiking, is a fair comparison — by adding the GPS and Movescount sync, it creates the opportunity for far more features.
If a Suunto rep reads this blog, please pass the word that I’ve love to test one out and write a review. If it’s primarily designed for “hikers and trekkers,” I can think of few better to give it a whirl.
[…] When you buy a GPS watch for an ultramarathon or other endurance event, battery life is of paramount importance. Here, Skurka analyzes the life of the top brands. […]
Another important aspect (at least for me) when talking about battery life is the ability to charge the watch in the middle of an activity. This definitely swayed my decision to replace my 310xt with a Fenix over the 920xt.
This is not an optimal technique for extending battery life, IMO. If you are stopped, it is fine; but if you are moving with a wire strapped to your wrist and a portable battery in your pocket, that is just downright annoying. I would rather decrease the recording interval (and have less accurate data) or simply let the watch die 15-20 hours into the race, at which point you are probably racing more on gut feel than based on watch data anyway.
I’m about to buy my first GPS watch and I’m very thankful to have really researched about it and stumble right here. Personally, my goal is just to record the data during a run/race, check the data later and be like a giddy kid looking at some lines; the route I took, elevation and change in pace. Wouldn’t mind putting my watch in my hydration vest while charging it since I really run/race most of the time based on gut feel. Thanks for this article! 😀 😀
Do you have any experience with Garmin’s Smart Recording? I’m wondering how much more battery life it provides compared to the one second recording interval.
Smart Recording dates back to earlier Garmin devices that recorded TCX files, which were inefficient and quickly filled up the on-board memory. Newer Garmin units record FIT files, which are smaller. When Smart Recording is on, the GPS still constantly runs, but not every fix is recorded. This reduces memory consumption but not battery consumption.
Only if your Garmin watch has UltraTrac (which is exclusive to the Fenix 3, Fenix 2, and Forerunner 920XT) can you affect the frequency with which the watch obtains a GPS fix. A 60-sec interval is fine for hiking, but it’s a pretty big gap for running. As I said in the post, at 7 min/mi pace it will record your position only every 754 feet. In theory, then, you could run in a circle with a 240-foot diameter and the watch would record you as not moving.
I have the Fenix 3. I tried the ultratrac mode and found the mileage to wildly off! On a paved path of know distance my data was short by 3 miles. I will not use the ultrac mode in the future. However the other features of the Fenix 3 are great. Also the ability to charge on the fly and still see the data is crucial for me.
Being frugal, I found my refurbished Garmin Fenix 1 for $100 on BuyDig a couple months back. With the latest firmware updates I haven’t found any drawbacks yet to the more expensive version 2’s and 3’s.
You show the Forerunner 15 as recording at 1 second intervals. This is not so on my (newly reconditioned) unit. 1 second may be the rate at which it gets afix, but the FIT file only records pints every 5-12 seconds depending on how fast I’m going (hills slow me down 😉 and whether I’ve deviated from a straight line. This looks more like ‘smart’ recording to me.
I’m trying to pick a simple and relatively cheap GPS watch to train for and participate in a long walk (100K/day, roughly twenty hours). The route is a canal path and therefore, I believe, perfectly straight. Does that mean that I don’t need to worry about the recording interval; since there are no twists and turns, one second and sixty seconds will have pretty much the same accuracy? Also, do you recommend any particular watch for this?
For this kind of route, the accuracy of the distance measurement will be about the same regardless of the recording interval. At least with my Suunto Ambit, however, my current speed data seems less accurate and seems less often updated when the recording interval is set to 60 seconds. I think it relies on the internal accelerometer in between intervals, which is less reliable than GPS.
Regarding a watch recommendation, I have nothing but great things to say about my Ambit 2, and so my recommendation would be in the Ambit family. The Ambit 2R is still available from Backcountry for $170, and a heart rate strap is included. It is not the cheapest option, but I think it’s probably the least expensive “good” option.
Many thanks for this – it is a godsend for someone who has never used a GPS watch before. I am planning something similar to Tom but solo on an offroad mountainous twisty route (but with very few trees) in the UK (Cape Wrath Trail) which is about 350KM over up to 6 days with overnight stops. I need to spit out a GPS track to prove where I went. Crucially, however there is virtually no electricity available on the route hence my preference for a Ambit3 Peak. I have no problem not having an accurate altitude readout but a large under or over estimation of distance could be an issue. Should the 3Peak set at 60 secs be able to cope with such a twisty off road track. Am also looking at a Fenix 3 Power pack combination.
Here’s a deeper dive on the Ambit3 accuracy in 60-sec mode, https://andrewskurka.com/2018/suunto-ambit3-peak-gps-watch-accuracy-okay/.
I feel like I’m missing some context with your trip, but I can’t think of a situation where the 60-sec track would be disqualifying if you just need to validate that you did it. Yes, it will miss some twist and turns. But the data will be consistent enough that no one should accuse you of, say, skipping a section or hopping in the back of a pickup truck.
Thanks. That is very helpful. May need to try to use the Good setting with a power pack. Am assuming can switch off overnight to save battery life and not lose the gps record. The Cape Wrath trail has no set length and many different variants so it is a question of how far the route you chose was in the time you did it. As mountains are involved there are several zig zag ascents and descents like in the example you showed which look as though they will get smoothed out and therefore shortened with a 60 second interval. Have still chosen the Ambit3 Peak as regardless of good or OK setting it has the longest battery life and I can also now buy in UK below £200. Will experiment on known length routes beforehand to calibrate. Thanks for or your help, very useful
Yes, you can turn it off at night and it’ll save the data.
The Good setting is not a bad option either. Very good accuracy, and will recharge in about 45 minutes with a portable battery.
Thank you that is reassuring. Been thinking about the route and days one and three are quite straight but day two has a lot of zig zags. Sorry to be a pain and definitely last question but are you aware whether the gps interval can be changed mid run on the Ambit 3 peak eg on days 1 and 3 have it at okay and day 2 on good?
Quick question: I’m actually looking for a GPS watch for animal research. We monitor the tracks of study subjects in order to assess ranging behavior. I’ve used trimble GPS units in the past, but the battery life is too short and its difficult to hold the unit and keep up with the animals. I think a watch might work well for this job, but we don’t have electricity at the field site, so downloading to a computer and charging will be issues. Charging will be the easier of the two to overcome. I’m wondering how much track data (likely at 5 sec intervals for 10 hour days) these types of watches can store? There will be no need to load background maps, or any other space-consuming items.
Hey Andrew – thanks for the informative article. I’ve been using the Suunto Ambit 3 Sport for about a year now, and love it when it’s set to the best (10 hour) battery life mode. For months I’d thought I was doing something wrong with the longer battery life modes (15 and 100 hours, respectively) because it simply would not track elevation gain / loss, and distance would be off by 20% or more on longer runs. I use the watch primarily for trail running / ultramarathons.
I finally got in touch with Suunto customer service, and this is their reply:
“We have communicated this issue and unfortunately there is no workaround. For Ambit3 Sport, the only way to get ascent/descent on any watch with GPS is setting GPS to best.
The fact is that if you do not have enough altitude point (if they are not saved every second), they will all get filtered out by hysteresis (a process which is there to ensure that the calculation does not take into account inconsistent readings). Thus we need the best accuracy for GPS to give us details of a vertical gain.”
My question is, have you run into this sort of issue as well? I find it very frustrating that, in essence, this watch has only one usable mode – the 10 hour mode. The other, longer battery life modes all sound good conceptually, but if they don’t track elevation gain / loss at all, and don’t track distance with reasonable accuracy, they’re all but useless.
That’s a total bummer, and I was unaware of that issue.
If you use Strava, one workaround is that you can tell Strava to auto-correct for the elevation. On an activity page, look for the hyperlinked “Elevation” stat immediately below the activity distance. Movescount may have a similar tool but I’m unaware of it.
I feel like some Suunto GPS watches are different only in their software, and it just seems foolish to me to withhold features when the hardware is there. But the Peak and Sport/Ru models have different hardware, too, and I suspect this is driving the difference. An inexcusable oversight, nonetheless.
It kind of blows me away that I haven’t seen this issue discussed on any reviews for the Ambit 3 Sport, or any forums. I can’t be the only one a bit pissed off about this unexpected wrinkle! It really cuts down the usability of the watch. And since I end up on quite a bit of technical terrain, charging the watch on-the-go with an external battery pack doesn’t strike me as a great option.
So, you lost me a bit on the hardware difference between the Peak and the Sport. It sounds like maybe the Peak has different hardware as well as software to the Sport, and perhaps doesn’t suffer from this limitation?
Thanks for your insight and quick reply. Keep up the great work (in the mountains and here on the site!)
I’m somewhat surprised that it hasn’t been discussed more widely, too. It’s a big wrinkle. However, you’re probably rare in using this feature. I would guess that only a fraction of Ambit users know that they can adjust the GPS interval, only a fraction of those actually adjust it when they go on a multi-day outing, and only a fraction of those would be inclined to say something after the fact when they get home and notice missing data.
I know that the Ambit2 and Ambit3 Peak record topographic data while set to 5- and 60-second intervals.
Here’s a 5-sec on the Ambit2: http://www.movescount.com/moves/move117463044
Here’s a 5-sec on the Ambit3 Peak: https://www.strava.com/activities/668897437
Here’s a 60-sec on the Ambit2: http://www.movescount.com/moves/move115807637
Yeah, to me it drastically reduces the functionality of the watch. But thanks for sharing those other examples. I wonder if this is just a big (yet relatively unnoticed) overlooked issue on the Ambit3?
Anyway I decided to just upgrade to the Peak and its better battery life. Since I bought the Sport from REI less than a year ago I can get all my money back and upgrading to the Peak doesn’t hurt so bad. Shouldn’t be too long now and they’ll be coming out with the Ambit4! Thanks for your help
How does Ambit display compare to Fenix, Core, Forerunner color and b/w ?
I agree battery life is critical and I think display visibility (day and night) is often underrated. I don’t care for inverted displays or Forerunner 230/235/630, which seem weak perhaps to bolster battery life. I also question if color is more about form than function, but admit I don’t have much experience with color watches to make a conclusion.
Thanks for information, as an ultra runner who uses a heart rate, how long for the battery in 1 sec GPS with a HR on? Would 5 sec GPS extend a lot (on strava, so can work around the altitude)?. 100 mile run app 16-17 hours needed….your thoughts appreciated. Ambit 3 Sport.
In my experience (which has been with the Ambit2/ANT) the battery drain of a HRM is pretty low. It may be higher with Bluetooth, but I still don’t think it’s dramatic.
Ambit3 Sport is spec’d to 15 hours at a 5-second interval, and I would not plan on it magically lasting longer than that. If you want to capture your entire effort, you may want to set up another mode set to the 60-second pings. Late in the race, when you notice the battery getting pretty low, switch it over. You’ll lose some accuracy but at least you’ll record it all. Refer to the other article about extending battery life for details.
Note that the Sport does not have a barometer (it uses GPS to calculate its altitude), so when you change the setting to 5 or 60 seconds, it no longer can accurately measure vertical. It’s not a big deal — there is a tool in Strava to fix it afterwards.
Andrew thanks for your reply, I will experiment, would the trail version of this watch last longer?
The Ambit3 Sport and Run have the same battery. The Ambit3 Peak has a better battery. It’s rated to 25 hours at 1 second, 50 hours at 5 seconds, and 200 hours at 60 seconds. Another perk: it has a barometer, so even at 5 or 60 seconds and keeps accurate vertical data.
I own the Garmin 10. Its one small piece of rubbish. The acclaimed 5 hours battery time is a joke. Mine can, if im lucky, hold battery for 60 min. It can hardly load when I put the charger into my PC. Stay away!!!
I’ve been looking for a battery comparison all over the internet, and yours is the only one that I could find.
I see you chart is from 2015, do you have an updated version by any chance ?
Sorry, nothing updated, but clearly it needs to be.
Would the battery life last the whole Comrades?????
It depends on how long it will take you to finish Comrades and what GPS ping setting you use. I would expect to finish well within 10 hours, and my Suunto Ambit3 Peak would still have nearly half its battery life remaining, even at the most accurate GPS setting.
This excellent post could use an update, is the Ambit 3 Peak still the standout choice for battery life on the trail?
I can’t believe the market hasn’t moved on in 4 years but I’m not finding a more recent and comparable analysis.
Remarkably, the Ambit3 Peak is still the easy winner for battery life. The newer GPS watches have optical HRM’s and color touch screens that consume more power. I’m unsure if these newer watches have bigger batteries, but I do know that they don’t outlast the Ambit.
Bought an Ambit 3 Peak recently and have a had a problem with a long run. I have it on the Good GPS Accuracy setting and set out on a 33 mile run. This was around London so in an urban area. The recorded distance was 33.4 miles, just about bang on. I paused it overnight and next morning set off on the same route back home. By the time I got home the return journey was about 36 miles. I checked the return track which included quite a few straight lines off route. Would this be because I came back on the same route and the return data points were too close or do you know of a memory/recording overload problem with very long runs? I hope its the former because I have a 200+ mile run next month. As an aside the battery life was about 24 hours compared with the stated 30 hours. I have the recording on interval as 1 second rather than 10 seconds. Would this make a difference? No of the PODs are on .Is there anything else I can turn off to prolong life?
Why did you not close out the exercise after the first day? The watch will save your workout, and you’re not going to fill the memory with just 70 miles of data, especially if you’re grabbing GPS location only every 5 seconds.
I think your problem was not saving and re-starting. When you start an exercise, the watch identifies satellites. 24 hours later, those satellites have moved, so the watch struggles more to pinpoint its actual location. Your track would have been more accurate on the return trip if it’d had the opportunity to re-find satellites before you started.
This was a trial for the 200 mile run next month. Trying to set a fastest known time for a particular route self-supported and need some evidence of where I have been. A single GPS file would be optimum. From what you are saying a compromise would be to close out at the end of each day and then restart plus pause for the 6 or so hours I will not be moving? Also a previous runner on the route created this. I guess now this could be compiled from multiple gpx files?
If you’re taking a 6-hour break, there’s no reason not to stop the watch after the first leg and restart it at the beginning of the second. Your GPX tracks will show clearly where you started and ended each leg, and when.