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.
——————————————
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
Reader-Powered Content
This content is not sponsored. It’s mostly me behind the labour of love, which is this site, and I appreciate everyone who supports it.
Support the site: Follow (free, fewer ads) · Subscribe (paid, ad-free) · Buy Me A Coffee ❤️
All articles are written by real people, fact-checked, and verified for originality. See the Editorial Policy. FTC: Affiliate Disclosure — some links pay commission. As an Amazon Associate, I earn from qualifying purchases.
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.
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)