Lab Tests Reveal Xiaomi 15 Ultra as New Battery Life Champion, Outperforming iPhone and Galaxy

According to ZDNET’s latest lab-based battery endurance tests, the Xiaomi 15 Ultra has emerged as the new benchmark for smartphone battery life, outlasting every other flagship device on the market—including Apple’s iPhone 16 Pro and Samsung’s Galaxy S25 Ultra. In a controlled environment simulating real-world usage patterns, the Xiaomi model delivered an unprecedented 14 hours and 37 minutes of continuous use, surpassing its closest competitor by over 90 minutes. The findings, published as part of ZDNET’s Lab Award series, signal a seismic shift in the premium smartphone landscape, where battery longevity has long been considered a weak point for Android flagships compared to Apple’s optimized ecosystem.

The testing protocol, developed by ZDNET’s engineering team, replicated a standardized daily usage cycle: 30 minutes of video streaming, 45 minutes of GPS navigation, 60 minutes of social media browsing, 30 minutes of gaming, 20 minutes of voice calls, and 90 minutes of screen-on time with 5G connectivity—all at 50% brightness and with background apps active. All devices were fully charged at the start, and tests were conducted at a consistent 21°C ambient temperature to eliminate environmental variables. The Xiaomi 15 Ultra’s victory was attributed to its 6,200mAh battery, coupled with an industry-leading 120W wired charging system and a highly efficient Snapdragon 8 Gen 4 chipset paired with Xiaomi’s HyperOS software optimizations.

Apple’s iPhone 16 Pro, despite its reputation for power efficiency, managed only 13 hours and 4 minutes. Samsung’s Galaxy S25 Ultra, which had led previous battery rankings, slipped to second place with 13 hours and 12 minutes. Both devices, while impressive, were hampered by higher power draw from their ProMotion displays and more aggressive background processes tied to iOS and One UI. Meanwhile, Google’s Pixel 10 Pro XL, recently crowned ‘Best Phone Overall’ by Tom’s Guide, ranked fifth with 12 hours and 48 minutes, suggesting that software elegance does not always translate to raw endurance.

Other notable performers included the Oppo Find X9 Pro, which placed third with 13 hours and 21 minutes, and the OnePlus 12, which impressed with 13 hours and 1 minute despite its smaller 5,400mAh battery thanks to aggressive power-saving algorithms. The iPhone 16 Pro Max, Apple’s largest model, came in fourth, proving that size alone does not guarantee longevity. Notably, no device from Huawei or Sony made the top 10, reflecting their shrinking market presence in North America and Europe.

Industry analysts suggest that Xiaomi’s win is not accidental. The Chinese manufacturer has invested heavily in battery chemistry, partnering with CATL to develop silicon-anode cells with higher energy density. Combined with adaptive refresh rate tuning and AI-driven app lifecycle management in HyperOS, the 15 Ultra represents a holistic approach to power efficiency. "This isn’t just about a bigger battery," said Dr. Lena Ruiz, a battery systems engineer at TechInsights. "It’s about the entire stack—hardware, firmware, and software—working in concert. Xiaomi has cracked the code for sustainable high performance."

Consumers may soon see ripple effects across the industry. Apple and Samsung are expected to accelerate their own battery and efficiency initiatives ahead of their 2027 launches. Meanwhile, Xiaomi’s success could elevate its global standing, particularly in markets where battery life is a decisive purchase factor. For now, the message is clear: when it comes to endurance, the throne has shifted—from Cupertino and Seoul to Shanghai.