Samsung is reportedly getting ready for one of the most requested upgrades for its flagship smartphones. As per the recent leaks, the upcoming Galaxy S27 Ultra is being tested with significantly larger battery options. This would mark the first major battery capacity increase for Samsung's Ultra lineup in several years. If the leak proves accurate, the Galaxy S27 Ultra could even pack a larger battery than Apple's rumoured iPhone 18 Pro Max.
Samsung is testing a larger battery for the Galaxy S27 Ultra
No official word from Samsung yet, but here is what the leak suggests:
Samsung is skipping the switch to those new silicon-carbon batteries – something a lot of Chinese brands are already doing. Instead, they are doubling down on old-fashioned lithium-ion, just making them bigger and better.
Samsung may continue using Lithium-Ion batteries
The tip came from X leaker Schrödinger (@phonefuturist), who says Samsung’s testing new battery cells from Samsung SDI in the 5,600mAh to 5,800mAh range.
Apparently, Samsung first settled on a 5,200mAh battery but then changed direction and started trialling these larger cells. If all goes smoothly in testing, the S27 Ultra could hit store shelves with more than 5,500mAh inside.
First battery capacity increase since the Galaxy S20 Ultra?
That would finally break the Ultra series’ long-standing 5,000mAh plateau. The S20 Ultra? 5,000mAh. S21 Ultra? Same. S22, S23, S24, S25, S26 Ultra? All 5,000mAh, with only small gains in battery life thanks to new chips and smarter software. This could be the first real leap in years, not just a minor tweak.
Sure, other brands are squeezing more juice into slimmer phones using silicon-carbon chemistry, but Samsung isn’t jumping ship—at least not yet. They’re sticking with proven lithium-ion cells, just tweaking their efficiency and design.
Could it beat the iPhone 18 Pro Max?
Now, let’s talk about the iPhone showdown. Recent rumours say Apple’s iPhone 18 Pro Max will ship with a 5,425mAh battery for eSIM models and 5,235mAh for those with a SIM tray. If Samsung brings out an S27 Ultra with a battery north of 5,500 mAh, the numbers will finally tip in Samsung’s favour—at least on paper.
A bigger battery does not automatically mean better real-world results. iOS and Android handle power differently, and Apple and Samsung use different processors that sip (or guzzle) battery in their own ways. We won’t know who comes out on top until both phones get tested side by side.