Samsung Tests 20,000mAh Battery with 27 Hours of Screen On Time

2025 is quietly becoming the year of absurd large-capacity smartphone batteries. The public has seen 7,000mAh and 8,000mAh packs become mainstream. Honor even surpassed the 10,000mAh figure that was once considered impossible.

Almost all of this progress comes from Chinese phone makers switching to silicon-carbon battery technology. Meanwhile, Samsung and Apple are looking slower to adopt these changes. But Samsung may not sit still in this big battery race for too long.

A tipster claims that Samsung's SDI division is testing a massive 20,000mAh dual-cell battery for a smartphone. It is reported that this battery is based on silicon-carbon technology.

The design is claimed to use two cells of unequal size. One cell is reported to have a capacity of 12,000mAh in a 6.3mm form factor, while the second cell is 4mm thick and adds another 8,000mAh. Combined, the system reaches a staggering 20,000mAh.

What makes this even more interesting is that a single 12,000mAh cell already surpasses the 10,000mAh battery found in phones like Honor's Win series. In other words, Samsung may have tested a battery capacity that goes beyond what is currently considered "extreme".

The 20,000mAh full charge setting can provide up to 27 hours of screen-on time and last for around 960 charging cycles per year, at least in theory.

However, this battery has a longevity problem as it is reported to have swollen during testing. Although the short-term performance is said to be strong, the long-term stability is still unresolved.

Another source added that the 8,000mAh cell allegedly bulged from 4mm thick to 7.2mm after testing, which is a serious sign of danger for use in smartphones. As always, this information should be taken with a little skepticism.