I’ve amended this post as it was misleading. 31aug I did a loooooong bike ride. I had various gadgets. The SPARTAN ULTRA was in bike mode but only paired with a STRYD HRM (HRV, per second) and had BEST GPS mode. The ride was 8hr45 long and by the end the battery was down to 42% ie it has used 58% in 8hr45. So we might get somewhere close to 16/17 hours in BEST mode for continuous sport usage.
As the original post, below, shows you won’t get 16/17 hours on holiday without re-charging as the normal 247 usage also takes a hit on the battery.
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This inadvertent test was because I forgot the charger when going away. So it gives an indicative amount of exercise time you might get whilst also using it as a watch (and playing with it 🙂 )
In ‘Away On Holiday’ Mode
Suunto Spartan ULTRA: Full GPS Accuracy ON but no sensors. Battery fully depleted after 6 days of use as a daytime watch PLUS just under 6 hours of sports usage PLUS fiddling about (which turns the colour screen on). The claimed life for the ULTRA is 18 hours, for a one-off race usage you would probably get over 12 hours…needs testing to PROPERLY verify continuous race/train usage.
COMPARE: Used simultaneously for sports but not as a day-to-day watch ie reduced power used for screen display:
Garmin 920XT – Full GPS+GLONASS, HRV/per-second recording, HRM, PM – 30% remaining with identical sports usage but not wearing as a watch.
I also draw your attention here to a long ride with a 920 and a 820 neither of which lasted 9 hours…although on ULTRATRAC mode the 920 easily lasts over 10 hours.
Last Updated on 16 January 2026 by the5krunner
My favourite kit and nutrition
- Injinji – Runners protect your toes. Avoid discomfort and minor injury. Run more. Run faster. I use them.
- Garmin 90-degree charging adapter — The small adapter that keeps your charging cables tidy. Essential for race day. I use one.
- Garmin charging puck — the fastest and most reliable way to top up your Garmin before a session. I use one.
- Ravemen FR300 — Front light that mounts directly under your Garmin or Wahoo head unit. Keeps your bars clean and your beam pointed where it matters. I use one.
- Body Glide – The blue anti-chafe stick that all swimmers and many runners use. I use it.
- Maurten — The race nutrition trusted by elite athletes. Gels and drink mixes engineered to be easy on the stomach. I use them.
- Garmin Varia RTL515 — A radar rear light that alerts you to vehicles approaching from behind. Pairs with your Edge or Garmin watch. I use this model.
- Favero Assioma Pro RS2 — The power-meter pedals most serious cyclists choose. Accurate, easy to move between bikes. I use this model.
- Garmin Forerunner 970 — A serious choice for a pro-grade triathlon watch. I use this.
- Polar H10 — My daily driver for accurate, waking HRV readings.
- Wahoo ELEMNT Roam 3 — The bike computer that has the feature Garmin lacks: usability. I use mine on most rides.
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tfk is the founder and author of the5krunner, an independent endurance sports technology publication. With 20 years of hands-on testing of GPS watches and wearables, and competing in triathlons at an international age-group level, tfk provides in-depth expert analysis of fitness technology for serious athletes and endurance sport competitors. ID
very disappointing battery life…
yes it was. I revised the post after re-doing the tests. came out better when the test done as single test not being confused with other long periods of usage
That’s pretty rubbish.. I’ve got a Garmin Fenix and manage to get over a week without GPS use and a week with several runs or a run and ride
i’m going to try it out just doing exercise continuously. it seems worse than it really will be (I wish I hadn’t written the post now!)
In my experience so far battery life seems quite good. I only last about 3% during a 2 hour ride through London with a connected heart rate monitor and GPS on “best”.
yes. you’re right. I re-did the test (and amended the above post a while back to reflect)