iPhone 17 Pro Battery Leak Suggests Slim Design and Lower Capacity

A leaked photo of what was initially thought to be the iPhone 17 Air battery is now being linked to the upcoming iPhone 17 Pro, highlighting just how compact Apple’s next-gen Pro battery could be. The mix-up came from leaker Majin Bu, who posted the image with the Air label, only to walk that back a day later. The confusion wasn’t entirely unfounded: the battery’s dimensions align with expectations for Apple’s rumored ultra-thin model.

Pro Battery Design Revealed in Leak

The photo shows an L-shaped battery enclosed in a steel shell—a design that echoes the thermal management approach introduced with the iPhone 16 Pro. Apple appears to be sticking with that strategy, as the steel casing is intended to improve heat dissipation and keep the device cooler under load.

Majin Bu, who shared the image, claims Apple is preparing two versions of the iPhone 17 Pro battery: one for eSIM-only models and another for variants with a physical SIM tray. An early capacity estimate of 2,900 mAh was later deleted, leaving the exact number uncertain.

Compared to recent Pro iPhones, that capacity, if accurate, would represent a step down:

• The iPhone 15 Pro had a roughly 3,274 mAh battery with a standard aluminum casing.
• The iPhone 16 Pro moved to a steel shell and reportedly packed in 3,582 mAh.
• The iPhone 17 Pro’s leaked pack suggests a drop to around 2,900 mAh, with the same steel housing and a variant split for SIM configurations.

No official capacity has been confirmed, but based on the photos, the slimmed-down profile stands out.

Also Read: iPhone 17 Pro Max to Feature 5,000 mAh Battery

Why the Battery Was Mistaken for the Air’s

Much of the confusion stems from how closely the leaked battery resembles what’s expected for the iPhone 17 Air. Apple’s rumored ultra-thin model is said to be just 5.5 mm thick at its slimmest point. That kind of form factor demands a trimmed-down power source, with reports suggesting the Air’s battery could land between 2,800 and 3,000 mAh.

Seeing such a slim battery in the wild naturally pointed observers to the Air. But if the Pro line is also getting a thinner, steel-cased battery, it could hint at a broader design shift across Apple’s premium lineup, not just the experimental thin model.

Implications for Heat, Charging, and Longevity

While a smaller battery might raise questions about battery life, Apple appears to be doubling down on thermal solutions. The steel case helps with heat control, which could be crucial if the iPhone 17 series supports the Qi 2.2 wireless charging standard, rumored to deliver up to 50 W. Higher charging speeds tend to generate more heat, making effective cooling essential.

In tandem, Apple is reportedly swapping out graphite cooling sheets for a vapor chamber system in the iPhone 17 Pro and Pro Max, a first for the iPhone lineup. The new cooling approach should keep the A19 chip running cooler and may boost battery efficiency in the process.

The battery will also reportedly use Apple’s low-voltage adhesive release system, a carryover from recent iPhones that makes servicing easier by simplifying battery removal.

The Real Question: Will Battery Life Hold Up?

The iPhone 17 Pro’s battery may be slim enough to be confused with the Air’s, but the challenge will be maintaining the same real-world performance users expect from a Pro model. If Apple’s efficiency improvements can offset the smaller capacity, the sleeker design might not come at the cost of usability.

Would a thinner battery bother you if daily battery life stayed the same? Sound off in the comments.