IoW Battery Test: Amazfit Cheetah 2 Ultra Hits 55hr Projection

IoW Battery Test – Cheetah 2 Ultra Does Well vs Garmin, Wahoo, Whoop, Polar
Here we look at the accuracy of Cheetah 2 Ultra (trail run). For a comprehensive look at every difference between the Cheetah 2 Ultra and Cheetah 2 Pro, see the full Ultra vs Pro comparison.

The start of the UK’s annual heatwave coincided with our group’s bike trip to the Isle of Wight. A nice hot day offers great conditions to test optical HR and to see whether the sun’s brightness cranks up display brightness, shortening battery life. Even better, the island is a fantastic place to ride — a full loop runs to over 70 miles, though today we kept it to 100km with far too many coffee and cake stops. Outside school holidays, the riding is extraordinarily quiet, the drivers we did encounter were invariably patient and courteous, and the road surface ranks a solid 9/10. There are a few potholes, but also long stretches of French-style smoothness. The terrain is lumpy with some genuinely challenging climbs if you seek them out — the Radio Tower above Ventnor being the obvious one, which we didn’t have time for today.

Devices on Test
Whoop MG (left bicep), Polar Verity SENSE (right bicep), Amazfit Cheetah 2 Ultra (trail running watch, left wrist), Wahoo Roam 3 and Forerunner 970 (right wrist) paired with TymeWear VitalPro.

 
Battery Life Test
Let’s start with the one to beat: the Forerunner 970, rated at an estimated 31 hours (specified as 26 hours, GPS-only). I had incorrectly set it to GPS-only mode, which could actually save battery, but to counter that the watch is a year old with plenty of use on it, so the battery will have degraded. It was paired to a Assioma PRO RS power meter (Rating: Excellent) and heart rate strap, with brightness set to MAX, AOD on, timeout at 15 seconds, and wake-on-gesture enabled. A new display behaviour introduced a few months ago dims the screen when you try to look at it — which it shouldn’t.

 

There was some slight oddness here. The chart shows the finishing battery at roughly 80% (recorded precisely as 80.46%), yet the on-screen widget, photographed at exactly the same moment, reads 78%. A 2% discrepancy — odd, but not alarming.

This test forms part of the watch battery life hub.
Cheetah 2 Ultra Battery Performance
I took these starting images before setting off while the overnight red-filter colour was still active — it returned to normal during the ride. Brightness was set at just over 50%, timeout at 15 seconds, and always-on was disabled (unintentional, but that’s what happened). GPS was set to Accurate mode, using all satellites.

Interestingly, I checked the Cheetah before going to bed and it showed 100% charge. More than eight hours later it was still showing 100%. There are a few plausible explanations: the watch has excellent overnight battery management, the battery gauge isn’t properly calibrated (measuring charge directly isn’t straightforward), or Amazfit intentionally ships new watches with a conservatively calibrated 100% — meaning there is a small reserve built in. Most watch companies do something similar to some degree.

The Cheetah doesn’t log battery state to FIT files, so I had to rely on photographs as evidence.

Starting charge: 100%. Finishing charge: 90%. That is a 10% loss over five and a half hours, which projects to a 55-hour GPS battery life (claimed up to 60) — well ahead of the competition here.

I forgot to note the Roam 3’s starting charge. Assume conservatively it was 100%. It lost 23% in five hours, giving it a GPS battery life of just over 20 hours in use (claimed up to 25 hours). That is consistent with results over the past year. Like the Cheetah, the Roam 3 holds 100% for a while before the figure starts to drop.
Amazfit Cheetah 2 Ultra – Heart Rate Performance
DCRainmaker’s Analyzer tool (beta) rates Amazfit Cheetah 2 Ultra heart rate accuracy as Good to Excellent for this section of the road ride. A separate cafe stop section was excluded as the Cheetah recorded no heart rate during that period which throws out the correlations.

Average: 118.57 bpm (2–3 bpm lower than Whoop MG at 121.49, Polar Verity SENSE at 121.05, and Garmin/ELEMNT at 120.64).
Bias vs reference devices: 0.0 to -2.1 bpm (negligible).
Agreement: mostly Excellent, one Good result vs Polar, which has wider limits of agreement.
Limits of Agreement: tight vs Whoop MG; wider (±26–31 bpm) vs others, indicating occasional deviations but strong overall correlation.

The Cheetah 2 Ultra is reliable for cycling HR with minor underestimation. You don’t need the stats to tell you that — it’s obvious from a graph, as it nearly always is.

 
Amazfit Cheetah 2 Ultra – GPS Performance
There is nothing significant to report across the full 100km route.

Both the Amazfit and the Garmin drifted slightly off-route on some corners — examples below. Bear in mind the Garmin was running GPS-only here, so the latest top-end Amazfit is performing on a par with a top-end Garmin in its most basic GPS mode. I would score both at least 9/10 in these conditions, though it is worth noting that an easy, open road loop on a clear summer day is about as forgiving an environment as GPS gets. These results do not transfer directly to running, dense woodland or deep urban canyons.

 
Conclusion
Three clear takeaways from today’s test.

Battery life is the headline. The Cheetah 2 Ultra lost 10% charge over five and a half hours in accurate GPS mode, i.e. estimated 55 hours — comfortably ahead of the Forerunner 970’s 26-hour rating and the Wahoo Roam 3’s 20-plus hours. If battery endurance matters to you, that gap is significant.
Heart rate accuracy on the bike was solid. The Cheetah ran 2–3 bpm low against dedicated chest and arm-worn references, which is a negligible real-world difference for almost every training purpose. The DCRainmaker Analyzer rates it Good to Excellent, and the chart backs that up.
GPS is competitive but not exceptional. Side-by-side with the Forerunner 970 in GPS-only mode, both watches produced near-identical tracks on a straightforward open road. The Cheetah holds its own in easy conditions; harder environments will be a more meaningful test. Results to follow!

Overall, today’s ride gives good reason to take the Cheetah 2 Ultra seriously as an endurance option. A fuller review will follow once I’ve had more time with it across a range of conditions. For a full comparison of the current Forerunner lineup including how the FR970 stacks up against the FR570, FR170 and FR70, see the best Garmin Forerunner guide.
Quick answers

What is the battery life of the Amazfit Cheetah 2 Ultra?
In this test, the Cheetah 2 Ultra lost 10% charge over five and a half hours in Accurate GPS mode, projecting to approximately 55 hours. That comfortably exceeds the Garmin Forerunner 970’s spec’d 26 hours (tested as 31 hours) and the Wahoo Roam 3’s measured 20-plus hours in the same session.

How accurate is the Amazfit Cheetah 2 Ultra heart rate monitor on a bike?
DCRainmaker’s Analyzer tool rated it Good to Excellent in this test. The Cheetah averaged 2–3 bpm below dedicated reference devices, which is negligible for most training purposes.

How does Cheetah 2 Ultra GPS compare to the Garmin Forerunner 970?
On this open road test both watches produced near-identical tracks, with occasional minor drift on corners. The Forerunner 970 was running GPS-only mode, so the Cheetah 2 Ultra matched it in the most favourable conditions possible. Harder environments will be a more meaningful comparison.

Explore the full resource library

This site covers endurance sport technology across a range of dedicated reference sections. Each one collects the most relevant articles, tests, and analysis on its topic in one place.

Buyer guides

• Best sports watch — tested recommendations by sport and athlete type: triathlon, running, marathon, cycling, hiking, and women
• Best Garmin watch — Forerunner versus Fenix by series, sport, and budget
• Best wearables — recovery trackers, heart rate monitors, running power meters, and female athlete tech
• Best cycling products — computers, smart trainers, power meters, and cycling heart rate monitors

Brand and product guides

• Amazfit — the full Amazfit range from Balance to Cheetah to T-Rex, accuracy tests, HYROX partnership, and Zepp Health analysis
• Apple Watch for Sport — athlete-first coverage of Apple Watch across running, cycling, and triathlon
• COROS — watches, features, and firmware across the full COROS range
• Garmin — the company, the platform and the full range, and the starting point for choosing across every Garmin product line
• Garmin Edge — bike computers from entry-level navigation to flagship endurance and mountain biking
• Garmin Fenix — every model, feature, and firmware development for Garmin's flagship outdoor watch
• Garmin Fenix 8 Series — which variant to buy, upgrade advice, accuracy data, and the full Fenix 8 review and firmware coverage
• Garmin Forerunner — the full Forerunner line covered from entry level to triathlon flagship
• Garmin Instinct — rugged GPS watches for endurance and adventure athletes
• Garmin Features Explained — how Garmin's metrics work, from Training Load and Body Battery to Race Predictor and HRV Status
• Google Fitbit — Fitbit Air, Google Health, Pixel Watch and the Wear OS platform
• Polar — watches, sensors, Polar Flow and training science across the full Polar range
• Suunto — Race, Vertical, Run and the SuuntoPlus ecosystem
• Strava — features, privacy, segments, and how Strava fits into a serious training setup
• Wahoo — KICKR trainers, ELEMNT bike computers, and the Wahoo ecosystem
• WHOOP — strain, recovery, sleep and the full WHOOP ecosystem

Specifications database

• Full Specifications Database — detailed spec sheets, battery life, sensor lists and generation-on-generation comparisons for current Garmin, COROS, Amazfit, Samsung, Google Fitbit, Huawei, Suunto, Wahoo and Apple Watch models

Sport and topic guides

• Running Watches — how to choose by discipline: road racing, trail, track, beginner, and multisport
• Triathlon and Multisport Technology — watches, sensors, and race-day tools for swimmers, cyclists, and runners
• HYROX — training science, race analysis, and technology for the functional fitness race format
• parkrun — technology, training, and performance for the weekly 5K
• Hiking Technology — navigation, safety, and trail tech for walkers and hikers
• Heart Rate Monitoring — optical sensors, chest straps, accuracy comparisons, and how to set training zones
• GPS Accuracy — how satellite systems perform across brands, terrains, and conditions
• Sports Watch Battery Life — battery claims, real-world tests, and how to manage battery life across Garmin, Apple, Amazfit and Coros
• Recovery Trackers — WHOOP, Oura, and the science of readiness scoring
• Female Athlete Tech — wearables, physiology, and performance for female endurance athletes, covering cycle-synced training, RED-S, HR accuracy, and VO2max
• Sports Science — peer-reviewed research on HRV, VO2max, lactate threshold, running power, wearable accuracy, and supplementation
• Testing Methodology — how this site tests GPS accuracy, heart rate, battery life, and other performance claims

Content series

• Release Radar — confirmed launches, leaks, and rumours across Garmin, Apple, COROS, Polar, Suunto, and Wahoo
• Deep Dive Feature Files — weekly firmware feature updates across all brands (bug fixes excluded)
• Fix Files — weekly firmware bug fix tracking across all brands

Last Updated on 11 August 2026 by the5krunner