iPhone Ultra battery: here's what we know so far

(Image credit: Foundry) Everything about the iPhone Ultra is going to be scrutinized under a much larger magnifying glass, so Apple can’t afford to gloss over some of the foldable’s biggest rumored features. One of the greatest areas of concern centers on battery life, given that it’s tipped to become the thinnest iPhone ever.Delivering all-day endurance in a foldable is notoriously difficult, especially when you factor in that these devices have expansive main displays compared to traditional slates. I’ve tested many of the best foldable phones, and our lab testing reveals the obvious: battery life remains a major area of opportunity.Knowing that Apple needs to strike a careful balance between battery endurance and a thin, lightweight construction, I’ll break down all the leaks and rumors surrounding the iPhone Ultra’s battery — while examining what its main rivals offer in terms of stamina.Split battery design (Image credit: AppleTrack)Based on regulatory filings released back in July and shared by leaker Digital Chat Station, Apple could be leaning toward a dual-cell split battery design for the iPhone Ultra to evenly distribute weight across its folding chassis. The configuration revealed in the filings pairs a 1,921 mAh cell with a larger 2,962 mAh one, bringing the total combined rated capacity to 4,883 mAh.Unlike many of its rivals, Apple isn’t planning to bank on silicon-carbon battery tech to power its upcoming foldable. While competitors leverage high-density silicon anodes that allow them to cram massive capacities into their foldables without adding bulk to their frames, Apple's decision to stick with conventional lithium-ion cells means the iPhone Ultra won't lead the pack in raw capacity. Swipe to scroll horizontally Row 0 - Cell 0 Battery Size Thinness iPhone Ultra 4,883 mAh (rumored) 4.5 – 4.8 mm Samsung Galaxy Z Fold 8 4,800 mAh 4.5 mm Samsung Galaxy Z Fold 8 Ultra 5,000 mAh 4.1 mm Motorola Razr Fold 6,000 mAh 4.7 mm Google Pixel 11 Pro Fold 4,806 mAh 4.8 mm Oppo Find N6 6,000 mAh 4.21 mm Honor Magic V6 6,660 mAh 4 mm The chart above highlights the disparity in raw capacity the iPhone Ultra faces against its main rivals. At 4,883 mAh, the iPhone Ultra would lag near the bottom of the pack, eclipsing only the Galaxy Z Fold 8 and Pixel 11 Pro Fold. On the other end of the spectrum, the Motorola Razr Fold, Oppo Find N6, and Honor Magic V6 all boast capacities of 6,000 mAh or more.Battery life is a big concern Swipe to scroll horizontally Row 0 - Cell 0 Battery Life (hrs:mins) Battery Size iPhone Ultra N/A 4,883 mAh (rumored) Samsung Galaxy Z Fold 8 12:20 4,800 mAh Samsung Galaxy Z Fold 8 Ultra 14:33 5,000 mAh Motorola Razr Fold 14:44 6,000 mAh Google Pixel 11 Pro Fold 12:31 4,806 mAh I’ve already mentioned how foldables don’t have the same level of endurance as traditional flagship models, but they are making dramatic improvements. Our own lab testing results show that the landscape is shifting rapidly for notebook-style foldables, raising the stakes for the iPhone Ultra.Sign up to the Tom's iGuide weekly newsletter with coverage on everything from product launches to software updates, this is your go-to source for the latest updates on all the best Apple content.Looking at the Tom’s Guide battery drain test — which involves having a device continuously surf the web over cellular at 150 nits of screen brightness until depletion — you can see how larger battery capacities inherently deliver longer battery life in the chart above.Leading the pack is the Motorola Razr Fold at 14 hours and 44 minutes, with the Galaxy Z Fold 8 Ultra not too far behind at 14 hours and 33 minutes. I think we have a good indication of where the iPhone Ultra could land based on the Galaxy Z Fold 8 and Pixel 11 Pro Fold's performances.If the iPhone Ultra does indeed end up packing a 4,883 mAh battery, I suspect it'll clear the 12.5-hour hump with ease — and possibly land closer to the 13-hour mark. While that would still fall short of the leaders, it will come down to something else entirely to prove that the iPhone Ultra is a legitimate endurance contender.A20 Pro could have the biggest impact (Image credit: Apple/Tom's Guide)I know firsthand that size is only one part of the equation because I only need to look at the devices topping our best phone battery life guide to be reminded of that. Despite leaks and rumors indicating that the iPhone Ultra will have a much smaller battery capacity than its rivals, endurance will ultimately come down to the efficiency of what's running under the hood. Specifically, I’m referring to the rumored A20 Pro chip, reportedly built on TSMC’s next-generation 2nm architecture.The A20 Pro could represent Apple’s biggest efficiency leap in years. Moving down to a 2nm architecture doesn’t just promise a performance bump — it should drastically slash power draw across the board. That advantage will be critical for balancing the heavy power draw demanded by the iPhone Ultra’s dual displays.If Apple can optimize power delivery to key hardware components, the iPhone Ultra could significantly stretch its endurance between charges. Given the sizable battery life gains between recent flagship generations, the A20 Pro might just defy everyone's expectations (including mine). While matching the 14+ hour times posted by rival foldables seems far-fetched based solely on a 4,883 mAh cell, the raw efficiency of a 2nm silicon could easily bridge the gap. Follow Tom's Guide on Google News and add us as a preferred source to get our up-to-date news, analysis, and reviews in your feeds. More from Tom's GuideiPhone Ultra exclusive: Gurman on price, release date rumors and 'day one' weapon against Android'We're not changing it': MapQuest hits No. 1 in App Store after refusing to rename Lake Ontario to Lake AmericaiPhone Ultra and 18 Pro Max unboxed ahead of Apple event — these could be the final designs John’s a senior editor covering phones for Tom’s Guide. He’s no stranger in this area having covered mobile phones and gadgets since 2008 when he started his career. On top of his editor duties, he’s a seasoned videographer being in front and behind the camera producing YouTube videos. Previously, he held editor roles with PhoneArena, Android Authority, Digital Trends, and SPY. Outside of tech, he enjoys producing mini documentaries and fun social clips for small businesses, enjoying the beach life at the Jersey Shore, and recently becoming a first time homeowner.