Smartwatches have become the main accessory to our smartphones, small wrist-based computers that deliver notifications, track our steps and health and do handy things such as handle contactless payments. But perhaps more annoyingly than with our phones, most of the best smartwatches still need charging once a day.

That looks set to change in a big way as Android brand OnePlus has just announced its latest smartwatch that claims to have an astounding 120 hours of battery life when not using the always-on display. If true this would demolish the 40 hours Samsung says its latest Galaxy Watch 7 can run for, with the same setting off. When on, the Samsung watch lasts for 30 hours.

The latest Apple Watch Series 10, meanwhile, can only handle 18 hours between charges, according to Apple.

OnePlus says it has upped the longevity from last year’s OnePlus Watch 2, which claimed a 100 hour battery life that Express.co.uk found accurate when we tested the device.

“Continuing the industry-leading battery performance of OnePlus Watch 2, the OnePlus Watch 3's revolutionary battery life is designed to support a demanding lifestyle,” OnePlus said. “Featuring an impressive 5-day (up to 120 hours) battery life in smart mode or up to 16 days in power saver mode, OnePlus Watch 3 also offers the convenience of a quick 10-minute charge providing a full day's power.”

OnePlus used this announcement to tease the launch of the new watch for February 18, though it released lots of information, aside from the price, as well as an image of the device (above) in Emerald Titanium and Obsidian Titanium colourways. That’s green and black to you and me.

The battery life builds on the OnePlus Watch 2’s trick of using two different processors, something the OnePlus 3 achieves with the Snapdragon W5 chipset alongside the new BES2800 MCU Efficiency chipset. OnePlus’s software uses the Snapdragon chip when it needs to do high-powered work, falling back on the efficiency chip most of the time to conserve juice.

“Battery energy density has increased dramatically thanks to the equipment of the OnePlus Silicon NanoStack Battery, which is used in OnePlus 13 as well,” OnePlus explained. “The battery capacity of the OnePlus Watch 3 has been boosted to 631mAh from 500mAh in the previous edition. In addition to increasing operational speed, this significant improvement dramatically reduces power consumption.”

Express.co.uk recently gave the OnePlus 13 a glowing four-and-a-half star review, finding it an excellent and cheaper alternative to the Samsung Galaxy S25 Ultra.

The firm said the Watch 3 also uses a more efficient and brighter display as well as 2D Sapphire Crystal for hardiness.

OnePlus cryptically said the new watch has “advanced health algorithms”, but we’ll have to wait till February 18 to find out exactly what that means, but the Watch 2 was a capable health tracking wearable thanks to accurate GPS and the ability to record scores of different workout types. OnePlus’s health app for Android is less polished than Samsung Health, so we hope there have been some improvements for this new generation device.