What the Code Actually Says
Developers and researchers digging through iOS 27 Beta 4 have found references to a dual battery management system — strings that describe two independently tracked power cells, separate charging states, and combined capacity reporting that differs from anything in the current iPhone lineup.
On its own, a code reference isn't proof of a shipping product. Apple routinely experiments with hardware configurations in software builds that never reach consumers. But the dual battery strings aren't isolated: they appear alongside references to a hinge mechanism, fold-state detection APIs, and display configuration identifiers that don't match any current iPad or iPhone model.
The combination of battery management code, hinge detection, and new display identifiers in the same beta build is more compelling than any single string would be on its own.
Why a Foldable Needs Two Batteries
A dual battery architecture makes sense for a foldable device in a way it doesn't for a traditional slab phone. When a foldable opens, two separate display halves activate — often with very different power draws depending on which half is the primary screen. A single large battery in one half creates unbalanced weight and heat distribution.
By placing smaller batteries in each half of the device and managing them as a unified pool (which is likely what the iOS 27 code describes), Apple can distribute weight more evenly, manage thermals independently per half, and potentially charge each side independently — useful if only one half needs a top-up.
Samsung's Galaxy Z Fold series uses a single large battery in the lower half, which contributes to the noticeable weight imbalance when open. Apple's reported approach would solve that problem from first principles.
🔋 The engineering challenge: Two smaller batteries in a hinge-divided phone must behave as one seamless power source. Apple's iOS 27 code suggests power management software is already being written to handle this — well ahead of any hardware announcement.
What We Think We Know About iPhone Ultra
Piecing together leaks from supply chain sources, code analysis, and analyst reports, here's the current picture of what a foldable iPhone Ultra might look like:
- Form factor: Book-style fold (like Galaxy Z Fold), not clamshell — opening to a large tablet-sized display
- Display sizes: ~5.5-inch outer display folded, ~7.9-inch inner display open (similar to iPad mini proportions)
- Chip: A19 Pro or A20 Pro, depending on launch timing
- Battery: Dual cells totalling ~4,500–5,000mAh combined
- Price: Estimated $2,299–$2,499, positioning it above iPhone 18 Pro Max
- Timing: Most likely 2027, not 2026 — the iOS 27 code is preparatory work
The 'Ultra' name would extend the existing Mac Ultra branding into iPhone territory, signalling a halo product above Pro Max rather than a replacement for it.
What This Means for the Current iPhone Lineup
A foldable iPhone Ultra won't replace standard iPhones — it will sit above them at a significant price premium. For the vast majority of iPhone owners, and certainly for anyone running an older device on iOS 15 or iOS 16, the foldable changes nothing about day-to-day app compatibility or usability.
The longer-term effect is subtler. The foldable will almost certainly require A-series chips that are incompatible with existing app binaries compiled for arm64e (the current architecture). Apps rebuilt to take advantage of the larger folded display will need to support different layout modes, potentially creating a new compatibility tier alongside the existing iPhone and iPad split.
For now, though, iPhone Ultra is a 2027 story — software preparation happening 12 to 18 months ahead of hardware release. Today's iPhones, and the devices that came before them, remain the relevant hardware for 99% of app developers.
Our verdict
The iOS 27 Beta 4 dual battery code is the most concrete software evidence yet that Apple is actively building a foldable iPhone. But it's a 2027 product at the earliest — and one that will sit far above existing iPhones in price and complexity. For current device owners, the practical impact is minimal until the foldable actually ships.
Your current iPhone isn't obsolete yet
Whatever device you're on, check which apps still support your iOS version — the answer is usually better than you'd expect.
Check your device's app compatibility →Also see: iOS 27 Beta: every device that gets it — and every device left behind · iOS 27 Beta 4: On-Device Recovery explained · MacBook Neo: the iPhone chip that ended up in a Mac