Battery life has become one of the most crucial factors in the smartwatch buying decision. While consumers expect their watches to offer health tracking, smart notifications, and smooth performance, the device’s endurance often determines how pleasant or annoying the overall experience is.
The OnePlus Watch 3, the latest entry in OnePlus’ wearable lineup, has attracted attention not only for its sleek design and upgraded hardware but also for its promise of long-lasting battery performance.
In this article, we’ll take a deep look at the battery life of the OnePlus Watch 3 and see how it compares to other popular smartwatches in 2025. We’ll evaluate performance under various usage scenarios, discuss charging speed, analyze battery optimization features, and position the OnePlus Watch 3 among its competitors.
The OnePlus Watch 3 at a Glance
Before diving into the battery comparison, it’s helpful to quickly outline what the OnePlus Watch 3 brings to the table in terms of features and hardware:
- Display: 1.43-inch AMOLED, 466×466 resolution
- Battery Capacity: 500 mAh
- Operating System: RTOS-based custom OS
- Connectivity: Bluetooth 5.3, optional eSIM (Pro variant)
- Sensors: Heart rate, SpO2, GPS, skin temperature
- Charging: Magnetic fast charging support
The OnePlus Watch 3 does not run Wear OS but instead uses a proprietary OS, which contributes significantly to its energy efficiency. This design decision enables OnePlus to focus on battery optimization, providing users with multi-day usage—a standout feature in an industry where daily charging is often the norm.
Claimed Battery Life: What OnePlus Promises
OnePlus claims the Watch 3 offers:
- Up to 14 days of battery life under standard use
- Around 7–10 days with heavy use (continuous heart rate, sleep, and GPS tracking)
- 5–7 days with the always-on display (AOD) enabled
- 75-minute full charge time
These numbers position the OnePlus Watch 3 well above many Wear OS and Apple Watch models. But how does it fare in real-world comparisons?
Battery Life Comparison With Popular Smartwatches
Here’s a side-by-side breakdown of battery performance between the OnePlus Watch 3 and several competing smartwatches, based on typical use:
| Smartwatch | Average Battery Life (Typical Use) | Heavy Use (With GPS/AOD) | OS |
|---|---|---|---|
| OnePlus Watch 3 | 10–14 days | 5–7 days | RTOS |
| Apple Watch Series 9 | 18–36 hours | ~18 hours | watchOS 10 |
| Samsung Galaxy Watch 6 | 1.5–2 days | ~1 day | Wear OS 4 |
| Garmin Venu 3 | 10–14 days | 5–6 days | Proprietary OS |
| Huawei Watch GT 4 | 10–14 days | 5–7 days | HarmonyOS |
| Fitbit Sense 2 | 6–7 days | 3–4 days | Fitbit OS |
| Google Pixel Watch 2 | ~24 hours | Less than 24 hours | Wear OS 4 |
Key Observations:
- The OnePlus Watch 3 competes directly with Garmin and Huawei, offering a similar or slightly better battery profile.
- Apple and Google watches remain the least efficient in battery life due to their feature-rich but power-hungry operating systems.
- The OnePlus Watch 3’s 500 mAh battery is well-optimized for long-term use thanks to its lightweight OS.
Real-World Usage Testing
Testing across different usage scenarios reveals how the OnePlus Watch 3 performs over time:
Light Usage (No GPS, limited notifications):
- Lasts 13–14 days
- Includes basic time display, occasional step tracking, and heart rate checks
Moderate Use (Notifications, fitness tracking, sleep tracking):
- Average of 9–10 days
- Daily step counting, 2–3 workouts per week, and full-time heart rate tracking
Heavy Use (AOD, GPS, frequent app usage):
- Lasts about 5–6 days
- Includes outdoor running with GPS, music playback, AOD enabled
In each of these scenarios, battery drain is consistent and predictable, which is essential for reliability. The fast charging time—approximately 1 hour and 15 minutes for a full charge—makes it convenient even if you forget to top it off.
How the OS Impacts Battery Efficiency
A major reason the OnePlus Watch 3 outperforms many competitors in battery life is its use of a proprietary RTOS (real-time operating system). Unlike Wear OS or watchOS, RTOS is lightweight, does not support third-party apps extensively, and limits background processes.
This trade-off may mean:
- Fewer available apps
- Limited customization
- But far superior battery efficiency
If you value long-term usage over app-rich ecosystems, the OnePlus Watch 3 is an ideal candidate.
Charging Speed and Convenience
The Watch 3 includes fast magnetic charging using the proprietary charging puck provided in the box. Compared to other smartwatches:
| Device | Time to Full Charge |
|---|---|
| OnePlus Watch 3 | ~75 minutes |
| Apple Watch Series 9 | ~60 minutes |
| Samsung Galaxy Watch 6 | ~90 minutes |
| Garmin Venu 3 | ~120 minutes |
| Fitbit Sense 2 | ~110 minutes |
The OnePlus Watch 3 isn’t the fastest in the category, but it strikes a good balance between speed and safety, avoiding battery degradation over time.
Battery Management Features
The OnePlus Watch 3 includes several tools to help extend battery life even further:
- Battery saver mode: Disables most functions except time display
- Smart battery optimization: Reduces background syncs and disables AOD during inactive periods
- Sleep mode: Limits screen activity and notifications at night
- Auto GPS shutoff: Ends GPS tracking if movement isn’t detected after a while
These features are subtle but help you squeeze out extra hours or even days from your charge.
OnePlus Watch 3 vs. Apple and Samsung: A Practical View
Let’s consider a user scenario.
Example:
- You’re going on a 4-day hiking trip with no access to power outlets.
- You want continuous heart rate tracking, GPS navigation, and basic notification access.
With OnePlus Watch 3:
- You can likely get through the entire trip on a single charge, especially with smart battery settings.
With Galaxy Watch 6:
- You’ll need to bring a power bank and charge daily.
With Apple Watch Series 9:
- Even with power-saving features, you’ll likely run out before Day 2.
This highlights a clear advantage for the OnePlus Watch 3 in long-term endurance use cases.
Is Battery Life Everything?
While the OnePlus Watch 3 excels in endurance, it’s important to consider what you’re trading off:
- No third-party app ecosystem
- Limited smart features compared to Wear OS or watchOS
- No LTE option in the base model
- Fewer advanced fitness metrics than Garmin
However, if your priorities are battery, build quality, and essential smartwatch functions, the OnePlus Watch 3 hits a sweet spot.
Final Verdict
The OnePlus Watch 3 delivers excellent battery performance, standing toe-to-toe with endurance leaders like Garmin and Huawei while outlasting nearly every Wear OS or Apple competitor. Thanks to its optimized RTOS and efficient hardware, the watch offers up to two weeks of usage, with real-world tests supporting claims of 9–14 days depending on features used.
If you’re someone who values not having to charge your watch every night—and can live without a full app store or LTE streaming—the OnePlus Watch 3 is a top-tier choice in 2025. It’s particularly suited for travelers, fitness enthusiasts, and users seeking simplicity and reliability over flashy extras.
