Apple Watch Ultra 2’s battery boost may not be as great as it sounds

Apple Watch Ultra 2
(Image credit: Future)

Battery capacity isn’t something Apple shares when it announces new hardware, with the company preferring to discuss stamina in terms of days and hours of usage. 

But, according to MacRumors, the information on the upcoming Apple Watch Series 9 and Apple Watch Ultra 2 has been hiding in plain sight in a Chinese regulatory database. 

The site reports no change on the Apple Watch Series 9’s capacity, with the 41mm and 45mm models staying at  282mAh and 308mAh respectively. Despite this, the watch is still rated as good for 18 hours of use — presumably because the promised 25% efficiency savings of the new S9 chipset have been absorbed by the brighter screen, which can now reach 2,000 nits. 

The Apple Watch Ultra 2, meanwhile, is a bit larger — though not by much. The site claims the battery has a 564mAh capacity — up from 542mAh (or about 4%) on the Apple Watch Ultra 1.

Again, Apple says that the Ultra 2 is still rated for 36 hours in regular use (with the S9 chipset’s efficiency helping to make the screen an even more searing 3,000 nits), but here’s where it gets a little confusing. The company also says that the Watch Ultra 2 can hit up to 72 hours in low-power mode — and that’s up from 60 hours on the original.

That sounds like the S9 chip might offer some clever tricks to eke out a bit more juice in battery-saving mode, but maybe not. As also spotted by MacRumors, the fine print for each demonstrates that the figures are reached via different methodologies.

The 60-hour figure is arrived at with 15 hours of hiking, “over 600” time checks, 35 minutes of app use, three minutes of talk and 15 hours of sleep tracking. The 72-hour total, meanwhile, comes from 360 time checks, 180 minutes of app use and two hour-long workouts with music via Bluetooth. In other words, we’re comparing apples and oranges here.

Hopefully the extra battery capacity means that users can eke out a few more hours from the watch, especially with some setting tweaks. Watch out for our full review soon, where we’ll dig into that and more, so you know whether to upgrade when the Apple Watch Ultra 2 is released on September 22.

Alan Martin

Freelance contributor Alan has been writing about tech for over a decade, covering phones, drones and everything in between. Previously Deputy Editor of tech site Alphr, his words are found all over the web and in the occasional magazine too. When not weighing up the pros and cons of the latest smartwatch, you'll probably find him tackling his ever-growing games backlog. Or, more likely, playing Spelunky for the millionth time.

Read more
iPhone 16e review.
iPhone 16e battery capacity revealed — here’s how it compares to iPhone 16
The Apple Watch Series 10, Apple Watch SE and Apple Watch Ultra 2 sitting next to each other on a wooden table
Best Apple Watch in 2025: Each model tested and rated by our experts
iPhone 17 Air render
iPhone 17 Air tipped for massive battery upgrade despite the thin design — here's what you need to know
Apple Watch Ultra 2 on a person's wrist outside
Apple Watch Ultra 3 and Apple Watch 11 rumored to finally get this long-awaited health tracking feature
OnePlus Watch 3
OnePlus Watch 3 looks to beat the Apple Watch with 5 days of battery life
Galaxy S25 Ultra showing the trailer for Captain America Brave New World
Samsung Galaxy S25 Ultra battery life tested — there's good news and bad news
Latest in Smartwatches
Atari 2600 My Play Watch
It's not just Pebble — Atari is back with a watch that lets you play retro games on your wrist
Pebble Core 2 Duo and Core Time 2 smartwatches
Pebble is back with two new smartwatches starting at $149 — how to preorder
Garmin Fenix 8 Sleep
New data reveals the average Garmin sleep score — do you sleep better or worse than most people?
Garmin Fenix 8 deal
Act fast! Unexpected discount sees Garmin Fenix 8 drop to its lowest price on Amazon
The coolest things the Apple Watch can do
7 best Apple Watch features you're probably not using, but should
Close-up of the Amazfit Active 2 and Apple Watch SE next to each other on a user's wrist
I put the Apple Watch SE vs Amazfit Active 2 through a 7-round face-off — here's the winner
Latest in News
NYTimes Connections
NYT Connections today hints and answers — Friday, March 21 (#649)
Xbox Elite Wireless Controller Series 2
Deleted image reveals Steam games in the Xbox app — here's what it could mean
Severance season 2 finale
How to watch 'Severance' finale online – stream final episode of season 2 tonight
Render of the alleged design of the iPhone 17 Pro
New iPhone 17 Pro dummy leak highlights redesigned camera and part glass body
Nintendo Switch 2
Nintendo Switch 2 just tipped for three display upgrades — here's what we know
Samsung S95F OLED TV
Samsung is developing the successor to OLED TVs — but TCL might beat it to the punch