iPhone Duo Battery: EU Filing Confirms 4,883mAh as Spec Sites Show 5,800mAh

Apple.com Apple has never published battery capacity in milliamp-hours on its own specification pages — but it is required to in Europe, and that regulatory obligation has now settled the iPhone Duo’s battery figures for good. An EU product data sheet filed ahead of the foldable’s October 23 launch date, first reported by German Apple publication macwelt.de, confirms a combined capacity of 4,883mAh (19.073Wh) across two cells, as documented in the EU product data sheet. Buyers checking spec aggregator sites will find conflicting figures — 5,400mAh on some, 5,800mAh on others — none of which trace to a verifiable source. The EU filing is the only confirmed official figure for the iPhone Duo.

Apple typically omits mAh from its spec sheets. The company describes battery life through use-time ratings — video playback hours, streaming hours, typical daily use — rather than raw capacity, so there is no mAh figure on apple.com for the iPhone Duo. The number exists in the public record because energy labeling regulations for smartphones require manufacturers to publish product data sheets for every smartphone sold in European Union member states under EU Regulation 2023/1669. These mandatory disclosures list battery capacity (in both mAh and Wh), repairability scores, and IP ratings that Apple does not surface elsewhere.

The iPhone Duo appeared in the German Apple Store ahead of its pre-order date, which triggered the obligation to publish the data sheet even before the device was available for purchase. A separate regulatory filing with Chemtrec — the American Chemistry Council’s hazardous-materials registry for shipping lithium batteries — produced a Chemtrec filing confirmed matching figures from a different regulatory direction in September. Neither the mAh figure nor the Wh figure appears on Apple’s own product page.

TidBITS, an independent Apple-focused publication that maintains a detailed historical battery-life table for every iPhone model, flagged the unsourced 5,400 mAh figure as unverified — noting that Apple has not published the Duo’s capacity on its own pages and that a widely circulated 5,400mAh figure traces to no primary source.

The 4,883mAh total is not evenly divided. According to the EU data sheet and Chemtrec filing, the larger cell — housed in the inner chassis half that holds the 7.6-inch display and the A20 Pro system board — holds 2,962mAh (11.567Wh, 44g). The smaller cell in the outer half, behind the 5.4-inch cover display, holds 1,921mAh (7.506Wh, 29g).

The split architecture is an engineering necessity, not a marketing decision. A book-style foldable measures just 5.2mm (0.2 in) thick when unfolded — the thinnest iPhone Apple has ever made. A single cell with the equivalent of 19.073Wh of energy would need to occupy the full usable volume of one chassis half, leaving no room for the logic board, display drivers, antenna arrays, or the hinge mechanism. Dividing the battery across both halves lets Apple fill the available space in each half independently without routing a large single cell across the hinge — the same engineering rationale documented in Nerd’s Chalk’s guide to iOS 27.1 dual-cell battery health architecture.

Apple described this at the September 9 launch event as placing “one high-energy battery on each side to maximize capacity while efficiently using internal space,” without naming a specific mAh figure at the time.

iOS 27.1 manages both cells as a single battery for the user: the status bar shows one battery indicator, and charging fills both cells through a single USB-C port. Internally, the operating system tracks each cell separately — iOS 27.1 displays distinct per-cell health metrics in Settings, including maximum capacity and charge cycle count, for each cell individually under Settings > Battery. That separation matters for long-term ownership: if one cell degrades faster than the other, a technician can potentially service or replace only that cell rather than the whole battery assembly.

Raw capacity is a poor proxy for how long a phone lasts, and the iPhone Duo makes that gap unusually visible because it has two screens with dramatically different power draw. Apple’s published battery life figures are:

The 44-hour outer-display figure approaches but does not match the iPhone 18 Pro Max, which Apple rates at 45 hours of video playback despite carrying a larger iPhone 18 Pro Max battery capacity of 5,391mAh (EU SIM-tray variant). The 31-hour figure for the inner display is substantially lower. The reason is display area: the 7.6-inch inner OLED is the largest panel ever fitted to an iPhone and draws considerably more power per hour than the Pro Max’s 6.9-inch OLED panel — the Duo’s capacity advantage over the iPhone 18 Pro (4,056mAh) is offset by the demands of a screen that is roughly 21% larger in area. A buyer who uses the Duo primarily in its folded, single-screen mode should expect battery performance close to a conventional iPhone flagship; a buyer who works primarily on the inner display will see materially shorter runtimes.

The macwelt.de battery analysis notes that Apple appears to have calculated its 51.5-hour total usage rating for the Duo — nearly matching the iPhone 18 Pro’s 52-hour total — on the assumption of balanced use across both displays. Heavy inner-display use will shorten that substantially.

Fast-charging speed requires a specific adapter. The 60W USB-C charger required is what Apple specifies to reach 50% in approximately 20 minutes — Apple does not include one in the box. That is 5 minutes slower than the iPhone 18 Pro Max: that device’s iPhone 18 Pro Max charges faster, reaching 50% in approximately 15 minutes with the same 60W charger. MagSafe and Qi2 wireless charging bring the Duo to 50% in approximately 30 minutes. Apple has not published times to a full charge for either method.

The 20-minute-to-50% figure is not a limitation the Duo shares with the current iPhone Pro lineup; it is a real, if modest, trade-off of the foldable chassis. Buyers upgrading from an iPhone 18 Pro Max should expect slightly longer charge top-ups if they are using wireless charging.

The Duo’s 4,883mAh edges out the Galaxy Z Fold 8 by 83mAh — a margin too small to produce meaningful real-world differences but enough to give Apple the capacity headline. Samsung confirmed at its Galaxy Unpacked 2026 event in London that the Z Fold 8, Z Fold 8 Ultra, and Z Flip 8 are the company’s first smartphones to use silicon-carbon battery adoption, which allows higher energy density in the same physical volume. The Korea Times documented Samsung confirmed at Galaxy Unpacked 2026 through Executive Vice President Moon Sung-hoon, who said at a press briefing that the company adopted silicon-carbon only after the chemistry met Samsung’s rigorous safety standards. Apple has not disclosed the battery chemistry used in the iPhone Duo.

The iPhone Duo priced at 1,999 dollars puts it approximately $100 above the Galaxy Z Fold 8 (starting around $1,899). The two devices are the closest pricing competitors in the premium foldable segment.

The iPhone Duo was unveiled at Apple’s “Surprise and Shine” event on September 9, 2026, marking new CEO John Ternus’s first major keynote since succeeding Tim Cook on September 1. Ternus described it as the most transformational change since original iPhone — a reference to his launch-day quote that “iPhone Duo is the most transformational change to iPhone since the original.” Key confirmed specifications include:

Pre-orders opened October 16. The iPhone Duo will be available at Apple retail and through select carriers beginning October 23 in more than 70 countries.

A question the EU data sheet does not answer — and one Apple has not addressed — is whether splitting the battery into two cells affects long-term health differently than a single-cell design. iOS 27.1’s dual-cell health monitoring in iOS means owners will be able to track whether the two cells degrade at the same rate. The inner cell, at 2,962mAh and 44g, handles the majority of the Duo’s power-intensive inner-display workloads; it may cycle more heavily than the outer 1,921mAh cell in users who frequently unfold the phone.

There is no independent data on this yet. The first generation of iPhone Duo units will not arrive until October 23.

Apple does not publish battery capacity in mAh on its own specification pages. The only verified figure — 4,883mAh — comes from Apple’s mandatory EU product data sheet, which Apple is required to publish for smartphones sold in European Union member states under EU Regulation 2023/1669. Spec aggregator sites that list 5,400mAh or 5,800mAh for the iPhone Duo are using unverified or pre-launch rumor figures; none of those numbers traces to an official document. The EU product data sheet and the separate Chemtrec regulatory filing are the only primary sources for the confirmed mAh and Wh capacities — a point confirmed by EU product data sheet.

Battery capacity and battery life are not the same thing. The iPhone Duo’s 7.6-inch inner OLED panel is the largest display ever fitted to an iPhone — roughly 21% more screen area than the iPhone 18 Pro Max’s panel — and that larger display draws more power per hour. When the iPhone Duo is used on its inner display, the additional power draw means its 4,883mAh gets depleted faster than a smaller display would allow. On the outer 5.4-inch screen, the Duo behaves more like a conventional iPhone, approaching the Pro Max’s 44- to 45-hour video playback rating. As ithinkdiff.com’s breakdown of battery life depends on display explains, this trade-off is built into the physics of powering a larger screen, not a weakness of the dual-cell design specifically.

A 60W USB-C power adapter is required for the confirmed 20-minute fast-charge claim. Apple does not include a 60W charger in the box; the included cable requires a separately purchased compatible adapter. MagSafe and Qi2 wireless charging are slower alternatives, reaching 50% in approximately 30 minutes. These are Apple’s test figures measured on drained units; charging times in typical daily use — topping off from a partial charge — will vary. Full details are in the charger required for fast charge guide.

iOS 27.1 tracks cycle count and maximum capacity for each of the two cells separately under Settings > Battery. This means owners will be able to see if the cells degrade at different rates over time — potentially useful diagnostic information if the phone requires service. Whether splitting the battery into two cells produces better, worse, or equal long-term health compared to a single-cell design of equivalent capacity is not yet known. The first iPhone Duo units will not ship until October 23, and real-world longevity data will take months to develop. The per-cell tracking feature was confirmed via dual-cell health monitoring in iOS.