Your Next Android Smartwatch Might Last 100 Hours on Battery

howtogeek.com:

Most smartwatches struggle to last 24 hours on a single charge. But the newly-released OnePlus Watch 2 boasts a maximum 100-hour battery life. This shocking accomplishment comes courtesy of the "hybrid interface" in Wear OS 4, meaning that a 100-hour battery may become commonplace in new Android smartwatches.

The Wear OS platform, which is co-developed by Google and Samsung, was overhauled in 2021 to better compete with Apple's watchOS. One major change was the introduction of a dual-chipset architecture. It's a pretty straightforward idea; heavyweight tasks are handled by a power-hungry application processor (AP), but background tasks are left to a more efficient microcontroller unit (MCU).

A developer-facing "hybrid interface" chooses when to utilize the AP or MCU. This gives manufacturers and developers the ability to tailor battery optimizations to certain tasks. Google's Pixel Watch, for example, uses the hybrid interface to supply per-second heart rate monitoring without a noticeable impact on battery life. Still, the Pixel Watch needs to be recharged every day. That's why Google is introducing a "substantially expanded" hybrid interface system that takes a more aggressive approach to common tasks, specifically notifications and messaging.

This "expanded" hybrid interface is responsible for the OnePlus Watch 2's extreme battery life. Instead of waking the power-hungry AP every time there's a new notification, the OnePlus Watch 2 diverts notifications to the efficient MCU. You can interact with, dismiss, or write a response to these notifications without transitioning to the AP, thereby saving a substantial amount of power without compromising the core smartwatch experience.

Other simple tasks, such as watch face rendering, are also handled by the MCU in Wear OS 4. And if a developer wants to optimize new apps or features for a batter battery life, they're free to do so with the existing Wear OS 4 APIs. This is in addition to the power-efficient health tracking