When reviewing the Apple Watch Series 11 last year, I found the battery performance across multiple complete power drain tests to be nothing less than superb. In fact, that’s the exact word I used.

Last year, Apple bumped up the estimated life to 24 hours (after holding steady at 18 hours for the previous 10 generations), and our testing more than justified this ambitious claim. In fact, real-world performance seemed roughly double that: In one test, the Series 11 lasted for 46 hours, and 49 in another. In both cases it managed a day, a night, another day, and then most or all of another night; the only question was how far it would make it into the morning of the third day. Impressive stuff.

With such high standards to live up to, I wasn’t sure what to expect from the Series 12, which I’m currently testing for an upcoming review. Officially it’s rated with the same estimate as its predecessor: up to 24 hours. Unofficially, I took note of the inclusion of continual heart-rate monitoring as the headline new feature and wondered how much of an impact this would have on battery performance. I was prepared for a dip in last year’s numbers that were still ahead of Apple’s estimates.

The impact of the new sensor, it appears, is not very much. Either that, or the new S11 processor has such a positive impact that it more than cancels out the energy burden of the health feature.

I’ve just completed my first complete battery test of the Series 12, and it lasted a whopping 51 hours, surpassing both runs of the Series 11 by at least a couple of hours. It lasted two full days, two full nights, and made it to mid-morning on the third day. By the standards of a fully featured smartwatch, that’s elite performance.

There are caveats, of course. This is only my first test, and I plan to run at least one more complete power-down before committing my thoughts to a full review. Battery performance is in any case quite subjective: there’s no established battery benchmark app as there is for the iPhone or the Mac, and battery life will vary based on usage. And on the negative side, my first charging test of the Series 12 suggests it powers up more slowly than its predecessor, requiring 57 minutes to get from 0 to 80 percent, compared to just 40 minutes for the Series 11. (Again, I plan to run this test again for reliability.)

Still, the early signs are that the Apple Watch Series 12 has managed to take one of the highlights of the Series 11 and surpass it. This is a promising start, to say the least.