Galaxy S27 Ultra battery life: the upgrade I want more than faster charging

The Galaxy S27 Ultra official launch is drawing near, and amidst all the leaks, rumors, and speculation, there's one particular upgrade that's almost mandatory at this point.

It's not the camera system, nor is it the chipset, the display, or the processor inside. Those are pretty much perfect, and they have been for the past couple of generations. But we need to talk about the battery.

The Galaxy S27 Ultra upgrade that would make me buy it

Ever since the inception of the Galaxy S Ultra series back in 2020, one spec has remained unchanged for seven generations. You've guessed it—it's the battery. The first Galaxy S20 Ultra featured a 5,000 mAh cell, and every model that came after it also sported the exact same capacity.

Samsung is so reluctant to touch the battery of the S Ultra flagship that midrange A-series devices have started to match the capacity, and even offer longer battery life due to their modest chipsets.

The pressure from Far East models sporting silicon-carbon batteries is also building up. We've seen several models surpassing the 10,000 mAh threshold, and flagships such as the Xiaomi 18 Pro Max and the OnePlus 16 sport 8,000 mAh and 9,000 mAh batteries respectively.

Silicon-carbon is the answer

The reason the aforementioned Far East phones could pack such high-density batteries inside their flagship models has something to do with a technology called silicon-carbon batteries.

You may have already heard about it, and we also have a detailed explainer article if you want a deep dive, but long story short, silicon is added to the anode of the battery to improve capacity.

This tech comes with its own limitations, as silicon is quite brittle and needs special coatings to keep the anode from forming dangerous dendrites (tree-like formations that can short-circuit and damage the battery). Silicon also expands by 280% to 400% during charging, which is another can of worms to keep closed.

But the good news is that most silicon-carbon battery manufacturers have sorted out the technology and are offering silicon-rich anodes with as much as 15% silicon content (the Xiaomi 17 cited 16% silicon inside its battery).

Samsung already hopped on the silicon-carbon train

Samsung made a careful step into silicon-carbon with the Galaxy Z Fold 8 series. The company took a conservative approach and boosted the battery inside the Galaxy Z Fold 8 Ultra to 5,000 mAh (up from 4,400 on the previous generation).

As silicon-carbon batteries go, this is a fairly modest improvement, but the Z Fold 8 series served as a test bed for the new technology, and Samsung is pretty sensitive to anything battery-related, given the Galaxy Note 7 fiasco.

Now, the good news is that silicon-carbon battery tech is coming to the Galaxy S27 Ultra, and the improvement in capacity might be bigger than what we saw with the Z Fold 8 series.

The latest leaked certification documents point toward a 5,700 mAh cell inside the Galaxy S27 Ultra, which is a 14% increase over the previous generation. What about fast charging, though?

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