iOS 27 beta 4 code mentions a multi-battery iPhone — likely the iPhone Fold or iPhone Ultra

Code strings in iOS 27 beta 4 reference an iPhone model with multiple batteries, corroborating a Weibo leak from earlier in July that Apple's forthcoming iPhone Ultra (or possibly the iPhone Fold) will ship with two separate battery cells totaling 4,883 mAh. The code analysis comes from Macworld's Filipe Espósito and was reported by 9to5Mac on July 20 2026.

This is the first hard software-side evidence for an iPhone with a multi-battery design, which until now had only been rumored through supply-chain whispers.

What does the iOS 27 code actually say?

The beta 4 strings, as reported by Espósito:

"The batteries in this iPhone are performing as expected." "The health of the batteries in this iPhone has significantly degraded."

The plural "batteries" is the key. iOS 26 and earlier versions of iOS reference batteries in the singular. The beta 4 strings explicitly use the plural form, which is consistent only with an iPhone model that has more than one internal battery.

The code strings sit alongside the existing single-battery iPhone references — Apple is preparing iOS to handle both designs simultaneously. The multi-battery code is gated behind an internal hardware check, so it does not appear on current iPhones running iOS 27 betas.

Which iPhone is this?

Two candidates:

1. iPhone Ultra — Apple's rumored ultra-premium iPhone. The "Ultra" name has been used loosely in supply-chain reporting, with some leaks pointing to a higher-tier Pro Max and others pointing to a foldable device. The multi-battery design is consistent with the foldable form factor, where two separate cells are required to fit around the hinge mechanism.
2. iPhone Fold — Apple's first foldable iPhone, expected to ship in September 2026. The Fold form factor almost certainly requires two battery cells: one in each half of the device, connected electrically but physically separated.

The most likely interpretation: this is the iPhone Fold. Foldables universally use dual-battery designs because the hinge prevents a single cell from spanning both halves. The iPhone Fold's dual cells are an engineering necessity, not a feature choice.

The Digital Chat Station Weibo post from July 15 is consistent with this. The leaker said Apple's forthcoming iPhone Ultra would include two batteries, and the regulatory filing he cited put the cells at 1,921 mAh and 2,962 mAh, for a combined 4,883 mAh.

Why would the iPhone Fold's battery capacity matter?

For foldable phones, the battery is a major engineering constraint. The hinge mechanism, the larger internal display, and the second cover display all consume power. A foldable iPhone with 4,883 mAh combined battery would be comparable in capacity to the iPhone 17 Pro Max's 4,823 mAh cell.

That is meaningful for two reasons:

1. Battery life parity. If the iPhone Fold delivers battery life comparable to the iPhone 17 Pro Max, it removes one of the standard objections to foldable phones (poor battery life). The foldable form factor would no longer force users to accept worse battery life than a traditional flagship.
2. Engineering validation. Achieving 4,883 mAh in a foldable chassis validates Apple's hinge and internal layout design. Foldables typically have smaller batteries than traditional flagships because of the dual-cell requirement. Apple closing that gap is a real engineering accomplishment.

For comparison, the Samsung Galaxy Z Fold 6 has a 4,400 mAh combined battery. The rumored iPhone Fold at 4,883 mAh would have ~11% more capacity.

How does this fit with Apple's other iPhone 18 battery leaks?

The iPhone 18 generation has been the subject of multiple battery leaks:

• iPhone 18 Pro Max: 5,425 mAh (eSIM) / 5,235 mAh (physical) per Macworld on July 2; 5,567 mAh / 5,391 mAh per Chinese regulatory database on July 6
• iPhone 18 Pro: 4,288 mAh (eSIM) / 4,056 mAh (physical) per Chinese regulatory database — barely changed from iPhone 17 Pro
• iPhone Fold / Ultra: 4,883 mAh combined (1,921 + 2,962) per Digital Chat Station, corroborated by iOS 27 beta 4 code

The 4,883 mAh figure for the iPhone Fold sits between the iPhone 18 Pro Max and the iPhone 17 Pro Max in capacity. Given the Fold's larger inner display and second cover display, the 4,883 mAh capacity is closer to flagship territory than to the typical foldable battery capacity.

What is still uncertain

Three open questions:

1. Whether the iPhone Ultra and iPhone Fold are the same device or different devices. Multiple reports use both names. If they are the same, the multi-battery design is for the foldable. If they are different, the iPhone Ultra could be a separate ultra-premium traditional iPhone with a non-foldable dual-battery design — which would be unusual but not impossible.
2. The actual iPhone Fold name. Apple has not officially confirmed the product name. "iPhone Fold" and "iPhone Ultra" are both used in supply-chain reporting, and Apple may use one, the other, or a third name (e.g., "iPhone 18 Fold" or "iPhone Air Fold").
3. Whether the iPhone Fold ships in September 2026 or slips to early 2027. Apple has reportedly been working through hinge-yield and inner-display-supply issues. The September launch window is still expected per multiple sources, but the production ramp could constrain supply.

What this tells us about Apple's iOS 27 work

The iOS 27 beta code shows Apple is preparing the software layer for at least three iPhone hardware designs running iOS 27 in fall 2026:

• The standard single-battery design (iPhone 18, iPhone 18e, iPhone Air 2 in spring 2027)
• The single-battery Pro design with variable components (iPhone 18 Pro, iPhone 18 Pro Max)
• The multi-battery design (iPhone Fold / iPhone Ultra)

This is a more fragmented hardware launch than Apple has done in any previous generation. The iOS 27 codebase has to handle all three designs simultaneously, with shared features (Apple Intelligence, Siri AI, the Notification Center changes) and device-specific features (variable-aperture camera on the Pro Max, the foldable form factor's app continuity).

The iPhone Fold / Ultra is expected to be unveiled at Apple's September 2026 event alongside the iPhone 18 Pro and Pro Max, with shipping starting late September 2026.