In recent years, foldable smartphone manufacturers have competed to make their devices thinner and lighter for easier handling and portability. However, this approach has introduced a major limitation: less space for high-capacity batteries.

To solve this, many companies have turned to silicon–carbon batteries, which increase energy density within the same footprint. But Apple is reportedly not following this route for its first foldable. Instead, it is said to equip the iPhone Fold with a battery even larger than the one in the iPhone 17 Pro Max. The downside? It will make the phone bulkier and heavier - possibly tiring to hold for extended periods.

iPhone Fold currently being tested with 5,400–5,800mAh battery

According to yeux1122, a source known for accurately predicting the iPhone Air’s battery specs, Apple is now testing iPhone Fold prototypes with batteries ranging from 5,400 to 5,800mAh.

For comparison, the eSIM version of the iPhone 17 Pro Max comes with a 5,088mAh battery. Even the lower end of the Fold’s test range would surpass current flagship Android phones like the Galaxy S25 Ultra or Galaxy Z Fold 7.

The source behind this leak is reportedly the same individual who accurately revealed the iPhone Air’s battery details, lending further credibility to the rumor.

An earlier report suggested that the iPhone Fold, when fully opened, would resemble two iPhone Airs side-by-side. Apple has previously demonstrated it can shrink the iPhone Air’s logic board without sacrificing performance, making room for a 3,149mAh battery.

Applying a similar strategy to the iPhone Fold seems technically feasible. However, trade-offs are inevitable: the device will be thicker and heavier.

Foldables are inherently heavier than traditional smartphones. Adding just a few dozen grams or millimeters in thickness could significantly affect the handheld experience, especially during prolonged use.

Still, Apple doesn’t seem overly concerned about making the device “chunkier.” Rumors indicate that the upcoming iPhone 18 Pro Max will also be thicker than the iPhone 17 Pro Max, suggesting Apple is prioritizing internal space for battery and thermal improvements.

For the iPhone Fold, a thicker design not only allows for a bigger battery - extending usage time - but also creates room for a larger vapor chamber. This component could dramatically enhance heat dissipation, a critical feature for foldables, which generate more heat and require robust thermal control during video recording or gaming.

Big changes ahead for Apple’s first foldable

No official specs on the iPhone Fold’s dimensions have been confirmed yet. However, a prior leak claims the prototype featured a 7.74-inch main display when fully opened and a 5.49-inch cover display.

Apple could still adjust these specs during mass production. In fact, many of its products go through significant design changes during testing phases. And for an entirely new product like the iPhone Fold, such adjustments are even more likely.

Available details suggest that Apple is heavily invested in the iPhone Fold project, willing to compromise on form factor to achieve better battery life and cooling. However, its potentially bulky size may spark debate - especially as rivals continue to optimize for lighter and thinner builds.

Then again, Apple’s history shows that it rarely rushes to market. Instead, the company tends to wait until it can offer a product that delivers a more balanced, user-focused experience. The iPhone Fold may be a prime example of that approach: not the thinnest or lightest, but reliable and resilient.

As of now, the iPhone Fold remains unconfirmed. But with leaks becoming more frequent and detailed, the product may be inching closer to reality.

Those eager to stay updated on changes in design, specs, and exclusive features should keep an eye out for further rumor roundups in the near future.

Hai Phong