The table in the tweet, which looks to be from a regulatory document, shows one device sporting two batteries. This makes sense for the Z Flip 4 as its folding design means there's not enough room for one regular-sized phone battery. One of the cells is rated for 2,555 mAh and the other for 1,040 mAh. Adding them together gets you 3,595 mAh.
MyFixGuide confirmed my claim, the Z Flip4 battery is 3700mAh pic.twitter.com/lJT0X6KOpEMay 20, 2022
That's higher than the 3,300 mAh capacity of the Galaxy Z Flip 3, but still below the 3,700 mAh capacity tipped by IU in this tweet and in previous leaks. This is likely because of the difference between a battery's "rated capacity" (the minimum guaranteed capacity for a device's cells) and the "typical capacity" (the average expected size of the battery), and the figure that tech companies use in their marketing. Therefore the 3,700 mAh rumor still stands up for now.
The Galaxy Z Flip 3 offered poor battery life when we reviewed it, so a larger battery is a must-have upgrade for the Galaxy Z Flip 4. Samsung will need to make the rest of the phone more efficient as well to make this happen, but hopefully changes like the rumored use of a Snapdragon 8 Gen 1 Plus chip will help there.
Combined with other rumors for a larger outer display, and that more powerful chipset, the Galaxy Z Flip 4 looks like a more refined version of the current model. Meanwhile, we're hearing that Samsung's other big foldable, the Galaxy Z Fold 4, has some more substantial updates on the way including a change to the aspect ratio of the displays and some new cameras.
Looking at the previous Galaxy Z launches, we should see the Galaxy Z Flip 4 and the Galaxy Z Fold 4 arrive in August. Until then, we'll be on the lookout for more rumors and leaks to keep you in the loop.