Adrian Kingsley-Hughes/ZDNET
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After a year and a half of using the iPhone 15 Pro Max, the battery performance had become disastrous—far worse than I had anticipated. I had conscientiously followed every piece of guidance Apple had ever offered to preserve battery health, meticulously managing charging cycles and temperature exposure. Yet, despite my diligence, the results were disappointing. With my upcoming upgrade to the iPhone 17 Pro Max, I have decided to abandon partial charging limits altogether and return to the traditional method of fully charging the device to 100% each cycle.

#### Beginning the Experiment
When I first unboxed my iPhone 15 Pro Max in September of 2023, I made a personal pledge: I would do everything possible to maximize the battery’s long-term health. Unfortunately, an accidental mishap rendered that phone unusable, forcing me to restart the experiment with a replacement unit in March 2024. I wanted to see, beyond casual usage, just how much longevity I could extract from Apple’s most advanced battery system by adhering to best practices.

#### The Public Fascination with Battery Life
In all my years observing and writing about technology, I have found few topics as enduringly divisive and obsessively discussed as smartphone battery performance. Articles, forum debates, and entire YouTube channels have been devoted to it, dissecting everything from charge percentages to background app refreshes. Apple’s decision to provide increasingly detailed battery metrics within iOS has only intensified this fixation. One of the most notable features introduced over the years even allows users to cap the maximum charge at a chosen percentage level—with the stated goal of prolonging long-term battery health by preventing excess chemical stress on the lithium-ion cells.

Yet this raises an important and practical question: if every percentage point of capacity influences daily usability, is it worth deliberately sacrificing one-fifth of that charge just to safeguard longevity? For many, the allure of a theoretically longer-lasting battery outweighs the immediate inconvenience. According to Apple’s own documentation, the iPhone 15 series and newer models are designed to retain about 80% of their original capacity even after 1,000 full charge cycles under what the company describes as “ideal conditions.” Intrigued by this claim, I resolved to replicate those so-called ideal circumstances as closely as possible.

#### Results in the Early Stages
Setting my phone to charge only up to 80% produced immediate and noticeable effects. Initially, my daily operating time was slightly constrained but still manageable. After a short adjustment period, I rarely ended the day with less than 35% remaining, so I grew comfortable with the routine. However, after roughly a year—355 charging cycles, or nearly one per day—the battery’s peak capacity had already slipped to 91%. This gradual drop suggested that even with careful management, chemical wear was inexorable.

At first, I tried to ignore these warning signs, but the diminishing runtime became increasingly burdensome. On the rare occasions when iOS would temporarily override the charge cap and top the phone up to 100% for calibration, I could feel the tangible relief of having a device that lasted significantly longer between charges. Those moments reminded me just how impactful the difference between an 80% and 100% charge can be in daily life.

#### The Decline
By September—roughly seventeen months after launch—the degradation had accelerated. The battery had endured 501 recharge cycles, hovering around 89% of its original capacity. Although that statistic might appear acceptable on paper, real-world performance told another story. Starting the day with an 80% limit often meant facing the dreaded low-battery warning before late afternoon. My once-reliable companion now needed to remain tethered to portable power banks, which had become integral to my everyday carry. Even temporarily increasing the charge limit back to 100% failed to fully restore confidence, as the overall endurance still felt severely compromised.

At that stage, replacing the battery wasn’t a viable option either. Apple’s repair policy typically restricts replacement eligibility until the device’s maximum capacity dips below 80%, leaving me in a frustrating limbo—trapped with a flagship phone that no longer delivered flagship performance. Ultimately, my conclusion was stark: for someone who relies heavily on their iPhone throughout the day, the functional lifespan of such a premium model effectively ends well before the two-year mark.

#### Transitioning to a New Device
Faced with dwindling usability, I decided to upgrade to the new iPhone 17 Pro Max. The contrast was dramatic. Instantly, I regained that long-forgotten feeling of reliability—waking up with a full battery and confidently expecting it to last the entire day without compromise. Admittedly, I know this period of abundance may be temporary, but for now, it feels refreshing to carry a device that performs effortlessly again.

#### Lessons from a Single Case Study
Of course, mine represents only a single data point—one individual experience that may not be universally representative. Perhaps my specific battery cell was simply weaker than average. Yet others have reached similar conclusions. Take Juli Clover of MacRumors, for instance, who conducted a comparable test over a two-year span. Her verdict aligned closely with mine: although limiting the charge to 80% might theoretically safeguard capacity, the real-world benefit proved minimal, while the drawback—less usable daily runtime—became impossible to ignore.

#### My Final Approach
In light of this, I am returning to full charging—restoring my device’s cycle to the traditional 100% threshold. However, I plan to rely on Apple’s “optimized battery charging” feature, which learns daily usage patterns and delays the final 20% top-up until shortly before the device is expected to be unplugged in the morning. In my previous experience, this intelligent timing mitigated battery wear far more effectively than a fixed charge cap. Combined with the iPhone 17 Pro Max’s improved thermal management, thanks in part to its vapor chamber cooling system, I’m optimistic that this balanced strategy will keep my new battery performing admirably for longer.

In the end, all I can do is hope—hope that this data-driven, more holistic approach will yield the long battery life that every iPhone owner dreams of, without having to compromise on practicality or daily endurance.

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Sourse: https://www.zdnet.com/article/i-charged-my-iphone-the-apple-way-for-2-years-heres-the-battery-condition-now/