Teardown: Xiaomi Mi Watch smartwatch

During lockdowns, there has been a lot of talk about strong sales for more traditional consumer electronics – laptops, PCs, displays, tablets, phones – even if only in the context of the trend’s impact on semiconductor shortages. As restrictions are relaxed, it may be time to take a closer look at the wearables market. While many of us have been exercising during the pandemic, the received wisdom is that just as many (if not more) have been packing on the pounds. So, there is an opportunity here and quite probably the inventory to support it.

The Xiaomi Mi Watch is a fitness-led smartwatch and the Chinese company’s latest entry in the category. At £99, it is aimed at the cost-conscious and those planning restorative workouts rather than the complete Arnold. To that end, it brings together creditable aesthetics, broad functionality and the fruits of Xiaomi’s experience with not only its predecessors but also the basic fitness trackers in its value-priced family of Mi Bands.

Like those products, the Mi Watch has such features as heart-rate monitoring, sleep tracking and stress analysis. These are now supplemented with a blood oxygen monitor – albeit one Xiaomi is careful to characterise as not medical-grade – and more accurate sensors generally.

Moreover, the Mi Watch will automatically pick up when you start exercise – there are 117 pre-installed modes – and offer algorithmic activity assessment based on Garmin’s Firstbeat technology via the associated Xiaomi Wear app. There is built-in GPS, courtesy of a four-​system platform from Mediatek subsidiary Airoha Technology, and Amazon Alexa compatibility. The display is a 1.39-inch circular AMOLED, at 454 x 453 pixels (329ppi). It also has text alerts.

The next impressive claim made for a smartwatch that does all this at its price point is for battery life: 16 days ‘typical’ with the display always on; 22 days ‘low battery mode’; and 50 hours ‘outdoor sports’. The Mi Watch’s cell is rated at 1.62Wh, higher than for rivals from Apple (1.17Wh), Samsung (1.3Wh) and Huawei (1.6Wh).

However, in comparison with a Mi Band, the aspect that personally appeals most about the Mi Watch is that it has two prominent physical buttons. Trying to get the right result from a touchscreen during exercise is a long-standing gripe against the Bands (and other similar trackers). Being able to launch the home screen or cycle through exercise options in such an old-school way represents, for this product sector, progress.

Beyond the more practical and less Apple Watch-like industrial design compared to Xiaomi’s first smartwatch, innovation lies mostly in the software.

As an iFixit teardown shows, the components are mostly commercial off-the-shelf (COTS), from the standard Airoha positioning platform to the ST micro­controller and beyond (although in those markets where it is now targeting higher margins, Xiaomi is also reportedly moving towards designing its own silicon). Comparisons with Amazon’s COTS-heavy approach to cost control seem fair.

For software, there are most notably the low-power optimisation and the integration of the phone with various Xiaomi apps. This is slick in terms of both analysis and the user interface. However, in optimising at very much an in-house level, the company has left out hooks into the wider fitness-product infrastructure. For example, you cannot pull raw data or its analysis and port it to generic apps like Strava. For the more casual owner, this may not be much of a problem, but it still feels like a bit of a miss.

Internal smartwatch design is getting better when it comes to repairability, but there are some issues that the form factor continues to present. In marking the Mi Watch at a middling 5 out of 10 for repairability, iFixit noted that “many components are grouped together and can’t be replaced individually”.

There are some positive notes. Access can be achieved mainly via screws and iFixit saw less glue than it has on other products. The connectors are modular and do not overlap. The battery can be replaced quite easily.

However, its teardown team goes on to note: “Smartwatches that open through the back usually come with very difficult screen repairs, and the Mi Watch is no exception. To free up the display assembly, we had to use a heat gun at about 300°C and a razor blade, causing the screen some damage.”

This kind of issue will need resolving over time. It is not simply a case of enabling third-party repairs. It suggests warranty costs will generally depress margins because more units may need to be replaced entirely.

This hints at a particular and more general design trade-off with fitness wearables. Some consumers find themselves initially willing to pay for all the bells and whistles but then find that wearing something so expensive during exercise makes them concerned about the risk of damage. Xiaomi has picked a price point where the device does much of the job without making the user too paranoid.

If it follows the path it is taking in phones, it will want to pull more profit out of that soon enough - and it cannot be the only company thinking that way.

Xiaomi Mi Watch: key components

Exploded view

1. Rear panel

2. Button cable

3. Motherboard

4. Bezel

5. Battery

6. Mid-frame

7. Display

8. Bezel gasket

9. Sensor bracket

10. Daughterboard (sensors)

11. Navigation buttons (2x)

Motherboard

12. Positioning module, Airoha Technology

13. Flash memory, Paragon

14. Microcontroller, STMicroelectronics