iPhone 15 owners seemingly got some great news yesterday: long-term battery health is better than Apple initially claimed. Twice as good, in fact! The company is now advertising a much larger number to represent how long its batteries will last. The trouble is, we’re not exactly sure if the batteries have gotten that much better — or if Apple has just changed how it talks about and tests them.

As reported by 9to5Mac, Apple retested the batteries in the iPhone 15 and 15 Pro and now claims they can maintain at least 80 percent of their original capacity for 1,000 charging cycles — double its initial claim of 500 cycles. Batteries naturally degrade over time, so the added longevity is welcome news. It’s particularly notable since iPhone 14 owners started reporting unexpected dips in battery health after less than a year of use.

But there are a ton of variables that contribute to how long a battery lasts, and it’s unclear if the new batteries are better or if Apple has started testing them differently.

Across both iOS and its website, Apple is now advertising the 1,000 cycle figure as being attainable under “ideal conditions.” That’s different from how Apple used to advertise its promise of 500 cycles, which were attainable under “normal conditions.” The term “normal conditions” now seems to have been scrubbed from Apple’s website and replaced with “ideal,” including when referring to older phones. Even battery claims that previously had no qualifiers now note they require “ideal conditions.” One instance of the language still appeared on a support page yesterday, but it was updated after The Verge emailed to ask for clarification on the testing conditions.

Normal and ideal are clearly different ways to use a phone, and it’s not apparent if Apple’s change in language also reflects a change in testing: the company declined to comment on the record when we asked about it. 9to5Mac reports that the improved battery health comes down to “continued updates to battery components and power management systems over the years,” which leaves a lot of room for interpretation.

It’s very unlikely Apple is making anything up here. Undoubtedly, the iPhone 15 battery will maintain the promised capacity for up to 1,000 charging cycles under certain conditions — but it would be useful to know just what those conditions entail. Apple’s support pages mention the phones’ built-in software features to help preserve battery life, and the iPhone 15 includes an option to limit charging to 80 percent to help long-term performance. Maybe checking that option in the settings menu is “ideal,” or maybe ideal is actually an even more controlled lab setting.

Battery health is a difficult concept to communicate due to how many variables are involved. Apple’s been under a lot of pressure to provide users with more data since it was caught throttling speeds on older iPhones due to battery issues. But the raw numbers — charging cycles or percentage of original capacity — can be hard to understand without context. And a claim that battery health is suddenly much better than originally thought? That probably deserves a little more context, too.