The iPhone 13 Pro Max is slated to ship with a much larger battery compared to its predecessor, according to a new leak. It will allegedly featureh a 4,325mAh cell, which is significantly higher than the 3,687mAh unit on the iPhone 12 Pro Max. The iPhone 13 and iPhone 13 Pro will both run 3,095mAh batteries.
https://www.notebookcheck.net/iPhone-13-series-battery-capacities-revealed-by-a-new-leak.542354.0.html