OnePlus Watch 3: The Battery King of Smartwatches

A dead smartwatch is useless—a black screen, staring blankly back after you raise your wrist to check the time for the umpteenth time. Battery life remains the number one problem with these wearables. Apple has made the same 18-hour battery life claim on the Apple Watch since the original, and although it can extend past that these days, you’re still not going to get a two- or three-day battery life without limiting some functions severely.

Lo and behold, OnePlus has delivered what the top dogs haven’t with its new OnePlus Watch 3: a thumping five-day battery life. While it’s slightly bigger than its predecessor, this smartwatch doesn’t rely on size alone to stretch run time, but on new battery technology. I have charged it once in the week I’ve been testing it—at the end of the fifth day—without having to turn off any features.

Yes, fitness trackers and some watches from brands like Garmin can last several weeks, but none of those have access to the wealth of apps and smart functions as an Apple Watch or Wear OS watch. That’s what makes this $330 OnePlus smartwatch exciting.

Battery Gains

Photograph: Julian Chokkattu

The impact of a five-day battery life is huge. Too often have I gotten into bed and looked at my watch, only to realize it’s going to die in the middle of my slumber, so I begrudgingly trudge to the charger on my desk and leave it there. Too often have I gone a day or two with a dead watch on my wrist because I kept forgetting to put it back on the charger. There has been none of this with the OnePlus Watch 3.

This is possible thanks to the new silicon-carbon battery technology inside the watch—OnePlus first used it in the OnePlus 13 phone, but companies like Honor have been employing it for some time. These batteries are denser, allowing them to carry a higher capacity without requiring a thicker battery. That’s why the OnePlus 13 can fit a big 6,000-mAh cell despite being thinner than the OnePlus 12, which has a 5,400-mAh cell. OnePlus calls this its Silicon NanoStack Battery, and so the OnePlus Watch 3 has a 631-mAh battery compared to its predecessor’s 500-mAh cell.

That’s not all, OnePlus continues the dual-engine architecture that it debuted last year. The OnePlus Watch 3 has two operating systems and two chipsets. The Qualcomm Snapdragon W5 chip powers Google’s Wear OS 5, which handles all the graphics-intensive tasks, whereas an upgraded BES2800 chip runs the Real-Time Operating System, which manages many of the background tasks.

Splitting this workload, in conjunction with the beefier battery, nets you five days of juice. Mind you, this is with the default mode. If you turn on power-saving mode, OnePlus claims 16 days of battery life. For context, Apple claims its Low Power Mode can make the Apple Watch Series 10 last 72 hours.

Photograph: Julian Chokkattu