Samsung is reportedly testing massive batteries for future Galaxy phones, including a 12,000mAh silicon-carbon pack and an 18,000mAh tri-cell design. Documents allegedly leaked from Samsung SDI show the company experimenting with stacked battery configurations to push capacity beyond current flagship limits. The 12,000mAh version uses a dual-stacked cell structure combining 6,800mAh and 5,200mAh cells, while the 18,000mAh variant stacks three cells vertically.

These prototypes suggest Samsung is finally addressing battery capacity concerns that have plagued its flagship lineup. The 12,000mAh battery reportedly measures around 9.0mm thick and targets 1,500 charging cycles before dropping to 80% capacity. The 18,000mAh version pushes thickness to 12.3mm with cells of 6,699mAh, 6,000mAh, and 5,257mAh. A massive 20,000mAh battery also failed testing at just 960 cycles, indicating Samsung still faces durability challenges.

This development comes as competitors like OnePlus offer 7,000mAh batteries with 100W charging, while Samsung's Galaxy S26 Ultra still ships with a modest 5,000mAh pack. The testing suggests Samsung is feeling pressure to catch up with Chinese manufacturers who have prioritized battery capacity over ultra-thin designs. While these experimental batteries won't appear in 2026 models, they signal Samsung's recognition that battery life remains a critical weakness in its flagship strategy.