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Two iPhone 17 Pro Max models — render credit AppleInsider
A leaker claims to have specifications for the battery in the forthcoming iPhone 17 Pro Max, and they fit with previous reports about the phone being thicker than before.
In March 2025, a generally reliable leaker reported that the body of the iPhone 17 Pro Max was increasing in depth to 8.725 millimeters, compared to 8.25 on the iPhone 16 Pro Max. The supposition was that this would allow for a larger battery, and AppleInsider calculated that as small as the difference was, it could potentially mean up to an additional 400 mAh.
Now another often reliable leaker, Instant Digital, has posted that the iPhone 17 Pro Max will have a 5,000 mAh battery — approximately 324 mAh more than its predecessor.
It’s the overlap in these two leaks that make them significant, and also more probably accurate. However, even if the new figure and the earlier physical size rumors are correct, it does not follow that the iPhone 17 Pro Max will have longer battery life.
That’s because it depends on the rest of the iPhone 17 Pro Max design. The new model is expected to add new technology that will not impact the battery — such as vapor chamber cooling — but there may be other new features that do.
Apple is introducing new battery charging systems with iOS 26, aiming to optimize battery life with better power management. While useful for all iPhones, it’s probable that these features were developed specifically because of how the expected iPhone 17 Slim must have a smaller battery.
There must be a similar issue with the iPhone Fold since that has to remain reasonably slim when closed. So, separately, Apple has reportedly been redesigning its iPhone fold display specifically to extend battery life.
It’s also been claimed that 2025’s iPhone 17 Slim, or Air, will use advanced silicon-anode battery technology developed by Japan’s TDK. This is believed to provide 15% more energy compared to current designs.
This technology is believed to only just be ready for mass production, so it will be limited to the iPhone 17 Slim. It’s likely, though, that if it’s correct that the battery is more powerful, that it will spread to the iPhone 18 Pro Max in 2026.
