The BLUETTI B300K is a high-capacity expansion battery designed to extend the power output of compatible BLUETTI power stations. With 2,764.8Wh of capacity (51.2V, 54Ah), it provides reliable backup power for home outages or off-grid energy needs, and can be stacked with multiple B300K units or mixed with B300 and B300S models to scale up to 58kWh of total storage when paired with the Apex 300.

The B300K uses automotive-grade LiFePO4 (Lithium Iron Phosphate) battery chemistry, rated for 6,000+ charge cycles at 80% capacity retention — roughly double the cycle life of previous-generation BLUETTI expansion batteries. It features AI-BMS battery management technology, an aluminum casing, and an integrated cooling fan for safety and longevity. When paired with the AC300 or AC500, the battery charges to 80% in approximately 45 minutes. A built-in USB-A port (12W max, 5V/2.4A) allows the B300K to function as a standalone power bank for smartphones, tablets, and small devices without requiring a host power station.

Compatible power stations include the AC200L, AC200MAX, AC300, AC500, and Apex 300. The unit weighs 65.04 lbs (29.5kg) and measures 20.67 x 12.87 x 8.23 inches. Charging temperature range is 32°F to 104°F (0°C to 40°C); discharging range is -4°F to 104°F (-20°C to 40°C). Each unit includes a Battery Connection Cable (CA90) and User Manual. Backed by a 3+1 year warranty with product registration.