Samsung Galaxy S27 Ultra Battery Details Leaked; Could Top iPhone 18 Pro Max's Battery Capacity

Samsung's Galaxy S27 Ultra could receive its first major battery upgrade in several years, according to a new leak. The handset is said to be under evaluation with a larger battery than previously expected, potentially giving Samsung's next flagship an advantage over the rumoured iPhone 18 Pro Max in terms of battery capacity. The latest leak also suggests the company may continue relying on lithium-ion technology instead of adopting silicon-carbon batteries, despite the shift by various rival smartphone brands.

Samsung Reportedly Testing Bigger Batteries for Galaxy S27 Ultra

According to an X post by a tipster known as Schrödinger (@phonefuturist), Samsung is reportedly evaluating 5,600mAh and 5,800mAh battery cells developed by Samsung SDI for the Galaxy S27 Ultra. The post further suggests Samsung had previously finalised a 5,200mAh lithium-ion battery before reopening evaluation of larger cells. If internal testing proves successful, the smartphone could launch with a battery capacity exceeding 5,500mAh.

The report indicates Samsung is continuing with conventional lithium-ion batteries instead of adopting silicon-carbon cells for the upcoming flagship. Several Chinese smartphone makers have already adopted silicon-carbon batteries because they offer higher energy density than conventional lithium-ion cells. Instead of changing battery chemistry, the company is reportedly working on increasing the efficiency of its current lithium-ion design.

If the rumoured upgrade materialises, it would mark the first increase in battery capacity for Samsung's Ultra series in several years. The Galaxy S20 Ultra, Galaxy S21 Ultra, Galaxy S22 Ultra, Galaxy S23 Ultra, Galaxy S24 Ultra, Galaxy S25 Ultra and the recently launched Galaxy S26 Ultra all feature 5,000mAh batteries. Although each generation has delivered longer endurance through hardware and software refinements, Samsung has continued to list the same 5,000mAh battery capacity.

The latest claim follows recent reports suggesting Apple's iPhone 18 Pro Max could feature a 5,425mAh battery in the eSIM version and a 5,235mAh battery in markets that continue to use a physical Nano-SIM tray. Should both reports prove accurate, Samsung's next Ultra handset would carry the larger battery capacity of the two devices.

Even so, battery size by itself is not a reliable measure of real-world battery life. Since Samsung and Apple use different hardware and operating systems, any direct comparison will depend on real-world testing after launch. Until Samsung officially announces the Galaxy S27 Ultra, the leaked battery specifications should be treated as unconfirmed.