iPhone Ultra: Code in iOS 27 Beta 4 suggests two batteries

With iOS 27 Beta 4, a detail has surfaced that supports a persistent rumor: For the first time, the system files contain wording that refers to multiple batteries in an iPhone. Everything points to Apple equipping the foldable iPhone Ultra with two separate cells – a first for the iPhone line.

Shortly after the release of iOS 27 Beta 4, developers scoured the system code and discovered text snippets that can only be explained by a device with more than one battery. This coincides with weeks of intensifying rumors surrounding the foldable iPhone Ultra, expected to launch in September. This new discovery adds a piece to the technical puzzle, previously only known through the supply chain.

What the code in iOS 27 Beta 4 shows

The crucial lines come from the battery health status messages. In addition to the familiar wording for devices with a single cell, Beta 4 now includes further variations that explicitly refer to the batteries – in the plural – of an iPhone. One message confirms that the cells are functioning as expected, while another warns of a significant decline in the health of multiple batteries. Filipe Espósito discovered and documented these passages on Macworld.

This means that for the first time, the official operating system confirms what was previously only known from supplier registrations: Apple is preparing an iPhone with more than one battery. Such a design has never existed in the iPhone line before.

Two batteries for the foldable iPhone

That the dual-battery system is part of the iPhone Ultra is considered a likely scenario. A leak in early July already revealed the specific battery capacities of the foldable: two cells with 1,921 and 2,962 mAh, totaling 4,883 mAh. This value is considered a minimum; a final capacity between 4,800 and 5,000 mAh is circulating in the supply chain.

The reason for the battery split lies in the design. A foldable device divides its interior into two halves along the hinge, making it impractical to accommodate a single large battery. Manufacturers like Samsung and Google have therefore long relied on one battery cell per side in their foldable devices. Two separate batteries also distribute the weight more evenly and may allow for faster charging.

Not the first indication of this kind

The dual battery is just the latest in a series of clues Apple has left in the iOS 27 betas. Previous builds already contained references to a foldable iPhone and a model with multiple displays. Similar fragments have also surfaced beyond the foldable – most recently, a code hint at a new Apple wearable with cameras. New hardware is often prepared in the system code long before it's officially released.

How much battery life the foldable will have left

The raw number is put into perspective. With around 4,883 mAh, the iPhone Ultra would fall between the Samsung Galaxy Z Fold7 (4,400 mAh) and the Google Pixel 10 Pro Fold (5,015 mAh) – competitive, but not record-breaking. At the same time, the classic flagship model is expected to offer more: Rumors suggest the iPhone 18 Pro Max has a significantly larger battery. Those seeking maximum battery life will likely find it more readily in the conventional Pro model than in the foldable original.

Ultimately, the decisive factor won't be the nominal value alone, but rather how efficiently the overall package uses it. A foldable device powers two screens, which consumes additional energy; the efficiency of the upcoming chip generation must compensate for this increased demand. And ultimately, the discovery remains a code fragment: it confirms Apple's intentions but doesn't replace any official statement – changes are possible before the official unveiling.

September is approaching

As the expected market launch draws nearer, the evidence becomes increasingly concrete. The code in iOS 27 Beta 4 transforms a supply chain rumor into a clue directly from Apple's own system – leaving little doubt that the first foldable iPhone will utilize a battery concept unlike anything Apple has used before. Final confirmation will come at the keynote in September. (Image: Shutterstock / tinhkhuong)