BLUETTI’s Apex 300 power station is a capable unit on its own, but its real advantage is this expansion port. The B300K battery pack plugs directly into it, transforming a 3,000-watt portable power source into a long-term energy reserve. This modular approach means your initial investment isn’t locked in; you can add capacity precisely when you need it, whether that’s for a weekend camping trip or preparing for a multi-day outage.

With a 2764.8Wh rating, the B300K essentially doubles the usable energy of the core Apex 300. The lithium iron phosphate (LiFePO4) cells inside are the key. They’re rated for over 4,000 charge cycles before dropping to 80% capacity, which translates to a decade or more of regular use. In practice, this pack lets you run essentials like a refrigerator, lights, and communication devices for days, not just hours. It recharges via solar just like the main unit, so you can keep it topped up off-grid.

This is a dedicated expansion, so it only works with the Apex 300. That’s a commitment to BLUETTI’s ecosystem. The combined unit is substantial, best thought of as a semi-portable power hub for your home base, RV, or worksite rather than something you’d move around lightly. For the right user, that trade-off delivers serious, reliable power that grows with your needs.