iOS 27 code confirms foldable iPhone will use dual batteries

There are two months to go until Apple’s expected September keynote, and iOS 27 Beta 4 just dropped its most explicit hint yet that a foldable iPhone is real.

Macworld dug into the beta’s code and found something no shipping iPhone has ever needed: battery health messages written in plural. The strings sit inside the Battery Health module and read “The batteries in this iPhone are performing as expected” and “The health of the batteries in this iPhone has significantly degraded.” There’s even a warning about “one of the batteries” potentially being non-genuine. Every iPhone on the market today uses a single cell, so these strings have no purpose unless Apple is preparing software for a device with two.

Foldable phones split their battery into two cells — one on each side of the hinge — to use the limited internal space efficiently. That’s exactly what Apple appears to be doing. Chinese leaker Digital Chat Station reported earlier that Apple’s battery suppliers have filed specs for two new cells rated at 1,921mAh and 2,962mAh. Combined, that works out to 4,883mAh, and supply chain sources expect the final capacity to land between 4,800mAh and 5,000mAh. For context, the Google Pixel 10 Pro Fold packs 5,015mAh and Samsung’s Galaxy Z Fold 7 runs at 4,400mAh.

This isn’t the first foldable-adjacent code to appear in iOS 27. The very first developer beta after WWDC in June included fields labeled “foldState,” “angleDegrees,” and “mechanicalAngleDegrees” — parameters that let the system detect whether the device is fully open, fully closed, or sitting at some angle in between. These are hardware-level necessities for a folding device and completely meaningless for a standard slab iPhone.

Multiple sources now point to a fall 2026 launch. China Securities Journal reported that supply chain insiders expect the first foldable iPhone to ship in the fall of 2026. Analyst Ming-Chi Kuo predicts the device will debut alongside the iPhone 18 Pro series at Apple’s September event, with pre-orders opening in Q4 2026 — a rollout cadence that mirrors the original iPhone X in 2017. Other supply chain reports claim mass production is already underway at Foxconn and that September plans remain unaffected by earlier hinge-related rumors.

From the system-level fold state detection, to the battery health code’s unambiguous plural references, to the dual-cell batteries already filed with regulators, the evidence stack is getting hard to ignore. Software code doesn’t guarantee a product ships, but when the OS, the supply chain, and the component filings all say the same thing, it’s a safe bet Apple is well past the prototyping stage. Whether the device ships as “iPhone Ultra” or “iPhone Fold” — and whether it actually lands in September — we’ll find out in about eight weeks.