The internal space constraints of the Galaxy S26 Ultra will continue to persist, as Samsung will likely need to make room for the S Pen, which obviously means that the best course for the company is to incorporate silicon-carbon battery technology. Unfortunately, going by the latest rumor, the final product’s cell size might not change compared to the Galaxy S25 Ultra or the previous-generation releases, as these continue to ship with 5,000mAh batteries. The same rumor also disappoints in the fast-charging claims, hinting that Samsung might limit the wattage to 45W.
Battery capacity for the Galaxy S26 Ultra is said to be ‘under 5,400mAh,' but the commercial version may continue to ship with a smaller 5,000mAh unit
Despite a previous rumor claiming that both Apple and Samsung were exploring bringing silicon-carbon technology to future devices, the Korean giant will take its sweet time before finally settling on bringing such batteries to its premium smartphone range. On X, @PandaFlashPro has a series of disappointing updates related to next year’s Galaxy S26 Ultra, with the first one being that the battery capacity is under 5,400mAh, with no 65W fast-charging.
Just recently, we reported that Samsung’s Galaxy G Fold, the company’s first tri-fold smartphone, was spotted on the 3C certification database, with its charging limited to 25W, indicating that the company has little to no interest in bumping up those wattages. Whether the firm keeps these limitations deliberately to avoid any unnecessary risks that will materialize into a second Galaxy Note 7 incident, or simply wants these batteries to last as long as possible, we cannot confirm.
Battery Capacity is not Final yet but Under 5400mAh "if" they Increase, Charging Speed not 65w, 120Hz Refresh Rate, No Under Display Camera.
— PandaFlash 𝕏 (@PandaFlashPro) June 8, 2025
What we can confirm is that Samsung is trailing behind its Chinese competitors in the battery capacity and fast-charging categories and fast. Even the Galaxy S25 Edge was a missed opportunity for the Korean titan because a Samsung executive explained that the sleek flagship does not use a silicon-carbon battery because it relies on agentic AI to improve efficiency. Assuming the company brings the same software optimizations to the Galaxy S26 Ultra, there is only so much you can achieve until the hardware becomes the limiting factor.
With silicon-carbon batteries, Samsung was estimated to have increased the Galaxy S26 Ultra’s capacity size to 7,000mAh, and that too while retaining space for the S Pen. We certainly hope the company adopts this technology sooner rather than later because customers will eventually find less of a reason to spend a premium on flagships if they keep missing out on key features.
News Source: @PandaFlashPro
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