Three years of testing Apple's 80% iPhone charge limit left a year-old phone at 97% battery capacity and a three-year-old one at 88%, with the tester still unconvinced.
Key Points:
- An iPhone 17 Pro Max held at an 80% charge limit for 12 months showed 97% battery capacity after 277 cycles.
- Older capped phones read 93% after two years and 88% after three.
- The tester still doubts the trade-off, and a 2024 data analysis found only a small benefit.
iPhone Charge Limit Results
Juli Clover, managing editor of an Apple news site, published the figures Tuesday after keeping the opt-in setting on across three generations of Pro Max phones since 2023. Her iPhone 17 Pro Max, capped at 80% for 12 months, showed 97% maximum capacity after 277 charge cycles, fewer than the 299 her previous phone logged in its first year. She called it her best result yet.
Two older phones, still capped and now used daily as test devices rather than as her main handset, show how those numbers age. The iPhone 16 Pro Max read 93% after 24 months and 343 cycles, down one point in a year, while the iPhone 15 Pro Max held at 88% after 36 months and 369 cycles.
Both older models stood at 94% at their own one-year marks. Clover said the newer phone's bigger battery and faster charging made the cap easier to live with, though she still carried a battery pack most places. She tried to charge over USB-C more than wirelessly, but said the vapor chamber cooling Apple added to that model may have mattered more.
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Juli Clover Verdict
The stronger reading did not settle the question for her.
Clover said giving up a fifth of her battery was still mostly not worth the capacity she kept, and she guessed uncapped phones would show similar readings. This year's report included no comparison device. She called Optimized Battery Charging the most hands-off option, said Apple's 90% and 95% limits might be a better choice, and has already capped her iPhone 18 Pro Max for a check-in in September 2027.
Battery Health Evidence
Outside data points to a real but modest benefit. A German Apple magazine analyzed 102 battery readings from iPhone 15 owners in 2024 and found a statistically significant, though small, gap between phones charged to 80% and those charged to 100%.
Clover's earlier rounds pointed in different directions. In 2024, her capped iPhone 15 Pro Max read 94% against 87% and 90% for two colleagues' uncapped phones, but a co-worker's uncapped iPhone 16 Pro Max beat hers by two points in 2025. Apple designs iPhone 15 batteries to keep 80% of their original capacity at 1,000 complete charge cycles under ideal conditions, twice the 500-cycle target for earlier models.
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