A deep dive into the Apple Watch batteries: The specs don’t tell the whole story

Apple tends to be quite reticent about the battery specs of its products, preferring to talk about how long the battery lasts. Focusing, in other words, on estimated hours rather than exact watt-hours. Still, those runtime estimates can still tell a story, and it was surprising to hear at the company’s recent “Awe Dropping” event how much those estimates have gone up for this year’s models.

For almost a decade, from the original model to the Series 10, the standard Apple Watch was given exactly the same estimated battery life: 18 hours. But with the launch of the Series 11, that number has jumped to 24 hours. Similarly, the Ultra 1 and Ultra 2 were both rated at 36 hours, but the Ultra 3 sees that number jump to 42 hours. (This year’s Apple Watch SE has the same 18-hour battery life as its predecessors, but we can’t have everything.)

If only we could peruse the tech specs and see why this year, for the first time, two out of three estimates have gone up dramatically. Ah, but we can! The watchmaker is obliged to make an official report about the nature and quantity of hazardous substances in its products, and that includes lithium-ion batteries. So we decided to jump into the official figures and find out what’s going on.

And the numbers make very interesting reading.

A big battery bump

As we can now clearly see, all three of the latest Apple Watch models have significantly larger batteries than their predecessors, and indeed any previous model in their line.

The Ultra 3, for example, has a 2.313 Wh battery, compared to 2.178 Wh for the Ultra 2. That’s an increase of around 6 percent. (The Ultra 2 was itself 4 percent ahead of the 2.09 Wh battery in the first-gen Ultra.)

The Series 11, in both sizes, gets a bigger upgrade, jumping by 10 to 11 percent compared to the Series 10. At 1.403 Wh, the 46mm version gets the largest battery so far to appear in a non-Ultra Apple Watch.

Oddly, given that it’s the only new model not to get an increased runtime estimate, the Apple Watch SE 3 gets the biggest capacity boost of all. Compared to the Apple Watch SE 2, the battery has been increased by 12 percent, to a more than respectable 1.276 Wh in the 44mm version. This means the new SE even has a larger battery than the significantly more expensive Series 10.

This year’s increases seem even more impressive when you realise that it’s common for them not to change at all. As the diagram shows, Apple installed identical batteries in its Series 7, Series 8, and Series 9, in line with their essentially identical chipsets… and those models themselves were only slightly ahead of the Series 6. The first two Apple Watch SE models also have very similar battery sizes.

Note that where multiple figures are given for a single model, this reflects the varying specs across different configurations. The bigger-screen variant will have a bigger battery, of course, but cellular connectivity is also sometimes a factor. You can read all the specs here:

Naturally we’ll check the battery performance of the new Apple Watches when we put review samples through our rigorous testing process, and let you know if they live up to Apple’s boasts. All of the models are available to pre-order now.