Samsung Tests Massive 20,000mAh Battery Delivering 27 Hours of Screen Time

Samsung SDI conducted validation tests on a dual-cell silicon-carbon battery with a combined capacity of 20,000mAh.

Samsung 20,000mAh Battery – Credits: X/Schrödinger

Samsung 20,000mAh Battery – Credits: X/Schrödinger

The prototype featured a primary 12,000mAh cell measuring 6.3 millimeters thick and a secondary 8,000mAh cell at 4 millimeters thick.

During the year-long test involving roughly 960 charge cycles, the battery achieved 27 hours of screen-on time.

Swelling occurred in the cells post-test.

"Battery Validation Samsung SDI dual-cell Si/C battery (20,000mAh). Cell 1: 12,000mAh @ 6.3mm Cell 2: 8,000mAh @ 4mm Results: 27h SOT, ~960 cycles over 1 year. Post-test: cell swelling detected → longevity failure," tipster Schrödinger posted on X on December 25, 2025.

The 8,000mAh cell expanded from 4 millimeters to 7.2 millimeters.

"Some extra size detail about the dual stacked cell Cell 1 (Primary): Capacity: 12,000mAh Thickness: 6.3mm Dimensions: 10cm × 6.8cm Cell 2 (Secondary / Competitive Stack): Capacity: 8,000mAh Thickness: 4mm Dimensions: 10cm × 6.8cm The 8000 MaH swole up from 4mm to 7.2mm," tipster S posted on X on December 25, 2025.

Samsung SDI contacted for comment provided no response.

The test focused on silicon-carbon technology, which Chinese phone makers have deployed in devices with up to 10,000mAh batteries.

If the further tests and research go well, Samsung will introduce the largest battery on a smartphone ever very soon.