“Apple Watch Ultra 3” vs “Garmin Fenix 8”: Has “Apple” Finally Caught Up in Battery Life?

The smartwatch market has long been clearly divided: some opted for complete ecosystem integration but required daily charging (“Apple“), while others chose limited smart features and weeks of battery life (“Garmin”). However, with the arrival of the “Apple Watch Ultra 3” and “Garmin Fenix 8”, these boundaries have become much less clear. While “Apple” talks about revolutionary energy-saving solutions, “Garmin” responds with even more efficient solar technology and optimization of AMOLED screens.

1. Technological Evolution: S-Series Chips vs. Garmin’s Power Management

The foundation of the “Apple Watch Ultra 3” is the new S10 SiP (System in Package). According to industry analysis, this chip uses a 3nm architecture, allowing for greater computational performance while consuming up to 20% less energy than the previous generation.

Apple’s Strategy: “Apple” does not increase the physical volume of the battery itself, as it is limited by the ergonomics of the case, but focuses more on the efficiency of the Display Driver IC and LTPO3 (Low-Temperature Polycrystalline Oxide) screen technology. This allows for a reduction in refresh rate to 1Hz in Always-On Display mode, significantly saving energy.

Garmin’s Strategy: The “Fenix 8” series widely integrates AMOLED screens with traditional MIP (Memory-in-Pixel) displays for the first time. One of Garmin’s strongest solutions is the Power Manager software, which allows the user to turn off specific sensors in real-time – a level of detail that the “Apple” ecosystem does not yet allow.

2. Battery Life: The Numbers and Reality

The question of whether “Apple” has caught up with “Garmin” depends on how we define “catching up”.

Apple Watch Ultra 3 Performance

The “Ultra 3” now operates for up to 48–60 hours in regular use mode. Using Low Power Mode, this number increases to 100 hours. While this is a very good result by “Apple” standards, it still means charging every 4 days.

Garmin Fenix 8 Performance

The “Garmin Fenix 8” (51mm model with AMOLED) operates for up to 29 days in smartwatch mode. If the model with Solar Charging and MIP screen is chosen, the operating time under sufficient lighting becomes almost unlimited (Expedition Mode).

Function	Apple Watch Ultra 3	Garmin Fenix 8 (AMOLED)
Smartwatch Mode	Up to 60 hrs	Up to 29 days
GPS Tracking	Up to 12–17 hrs	Up to 60–80 hrs
Low Power Mode	Up to 100 hrs	Up to 90 days
Charging Speed	Fast Charging (0-80% in 45 min)	Standard (1 to 2 hrs)

Conclusion:No, “Apple” has not yet caught up with “Garmin” in pure operational duration. However, they have reached a “psychological barrier” – users can go for a weekend in the mountains without bringing a charger, which was risky for “Ultra 1” or “Ultra 2” owners.

3. GNSS and GPS: Energy Consumption at the Cost of Accuracy

One of the biggest battery “drains” is Multi-band GNSS (L1 + L5 frequencies). The “Apple Watch Ultra 3” uses advanced algorithms that automatically switch frequencies based on the environment (e.g., dense forest vs. open field) to save energy.

The “Garmin Fenix 8” uses SatIQ™ technology. This is a smart mode that determines when Multiband GPS is needed and when a single frequency is sufficient. Studies published on the accuracy of wearable device sensors (Journal of Sensors) show that “Garmin” algorithms still better optimize the signal strength and energy ratio over long distances (e.g., ultra-marathons).

4. Sports Metrics and Recovery Time

While battery life is important, “Fenix 8” users also value it for the Training Readiness and Body Battery features. These metrics require continuous Heart Rate Variability (HRV) monitoring.

The “Apple Watch Ultra 3” has made significant progress with the Vitals app and improved Training Load tracking. However, “Apple’s” philosophy continues to rely on a “reactive” approach (showing what has happened), while “Garmin” takes a “proactive” approach (advising what to do next). The larger battery capacity in the “Fenix 8” model allows for more complex data analysis on the device itself (On-device processing), without sending data to the cloud, which also saves energy in the long run.

5. Display: Brightness vs. Longevity

The “Apple Watch Ultra 3” display reaches 3000 nits brightness, which is necessary in direct sunlight. However, such brightness is the biggest enemy of battery life.

The “Garmin Fenix 8” AMOLED version offers a similar aesthetic view, but their UI/UX is designed based on dark themes to take advantage of AMOLED benefits (turned-off pixels on a black background do not consume energy). The “Apple” interface is more colorful and dynamic, making it look more attractive, but in terms of battery, it is technologically less efficient.

Final Verdict

Has “Apple” finally caught up? Technically – no, functionally – almost.

For most users who are not professional Ironman participants, the battery life of the “Apple Watch Ultra 3” is sufficient. However, the “Garmin Fenix 8” remains a strong leader for those for whom battery life is a guarantee of safety. “Apple” has caught up with “Garmin” not in terms of days but in the ability to offer “sufficient” time along with the best smartwatch experience on the market.

For the “Garmin” user, battery life is a feature, for the “Apple” user, it is still a constraint that must be accepted.

Sources and Additional Literature:

Google Scholar: “Performance analysis of multi-GNSS tracking in wearable devices under varying canopy conditions” (2025). Journal of Geodesy and Geoinformation.
Google Scholar: “Energy consumption patterns in LTPO3 display architectures for wearable electronics” (2024). IEEE Transactions on Consumer Electronics.
Apple Technical Specifications: Apple Watch Ultra 3 Environmental and Performance Report (2025/2026).
Garmin Engineering Blog: Deep dive into SatIQ™ and Battery Management in Fenix 8 series.
ResearchGate: “Accuracy of heart rate variability (HRV) metrics in high-end sports watches: A comparative study of Garmin and Apple sensors”.