The Galaxy S27 Ultra (Galaxy S27 Ultra) will likely experience one of the biggest battery changes in recent years for Samsung's flagship series. According to rumors, Samsung may increase the battery capacity from 5000 mAh in the current generation to 5700 mAh; but more interestingly, the apparent improvement is in charging speed without a noticeable increase in charging power.
According to ITNA citing PhoneArena, based on information released by a leaker, the Galaxy S27 Ultra may still use 60W charging, but the difference will be in the charging curve. Simply put, the phone can charge at a high rate for a longer period at the start of the charging process. This change allows the device's larger battery to fill up in a shorter time without needing an increase in nominal charging power.
This can be significant; because the Galaxy S26 Ultra with 60W charging can, according to Samsung's tests, fill about 75 percent of the battery in 30 minutes. In tests conducted by PhoneArena, the S26 Ultra reached 76 percent after 30 minutes and took 49 minutes for a full charge. In contrast, the iPhone 18 Pro Max reaches 71 percent after 30 minutes and needs about 1 hour and 8 minutes for a full charge.
However, the 5700 mAh capacity is probably not the whole story. Apple has used metal battery technology in the iPhone 18 Pro models and Chinese companies are apparently also exploring combining this technology with silicon-carbon batteries. Such a combination could in the future raise flagship phone battery capacities even above 10,000 mAh.
The potential Galaxy S27 Ultra capacity would be about 14 percent higher than the S26 Ultra, but this increase will not be noticeable to all users. Some users expect Samsung to use silicon-carbon batteries with much higher capacity like Chinese competitors.
Nevertheless, increased capacity does not always mean a better experience. Battery longevity also matters. A 10,000 mAh battery that suffers a severe performance drop after one or two years is not necessarily a better choice. Therefore, if Samsung can simultaneously offer greater capacity, faster charging, and battery health preservation over two or three years, the Galaxy S27 Ultra could be a strong competitor to Chinese flagships.