BLUETTI B500K vs. B300K: Comparison of the Expansion Batteries

You've made the decision to expand your BLUETTI power system, a significant step towards greater energy independence. Whether you're bolstering your home backup for peace of mind, gearing up for extended RV living, or planning serious off-grid adventures across Australia, adding more battery capacity is the key to unlocking longer runtimes and more possibilities.

When it's time to grow, BLUETTI offers two primary expansion options: the high-capacity B500K and the versatile B300K. While both are excellent choices, they are designed with different needs in mind. This guide provides a clear, honest comparison of these two powerful batteries to help you choose the perfect match for your specific energy goals.

At a Glance: B500K vs. B300K Key Specifications

Let's start with a direct comparison of the core specifications. This table highlights the key differences at a glance:

Breaking Down the Key Differences

1. Capacity: How Much Power Do You Need?

The primary differentiator is raw energy storage.

• The BLUETTI B500K offers a massive 5,120Wh of energy storage. This makes it the premier choice for users who need maximum capacity to run high-demand appliances for extended periods or want to build a comprehensive home backup system. To put that in perspective, this is nearly double the energy of the B300K, enough to run a typical full-size refrigerator for several days during an extended outage, not just a single day.

• The BLUETTI B300K provides a substantial 2,764.8Wh. This is a significant upgrade that offers impressive runtime for essential devices, making it a fantastic all-around option for both home backup and travel.

2. Longevity and Durability: A Tale of Two Lifespans

Both batteries are built with safe and durable LiFePO₄ (Lithium Iron Phosphate) chemistry, ensuring a long and reliable service life. However, their cycle life ratings differ:

• The B500K is rated for 4,000+ cycles, meaning it can be fully charged and discharged over 4,000 times before its total capacity dips to 80% of the original—a design built to last up to 10 years.

• The B300K is rated for an exceptional 6,000+ cycles using 'Automotive-Grade' LiFePO₄ cells, a benchmark of durability that translates to over 17 years of reliable performance with daily use.

While both are built for long-term reliability, the B300K's higher cycle count makes it an outstanding choice for users with extremely high-frequency charge and discharge patterns, such as daily off-grid use.

3. Compatibility and Scalability: Growing Your System

You can confidently expand your system knowing that both the B500K and B300K are designed to integrate seamlessly with BLUETTI's most popular modular power stations.

Both batteries are compatible with the following models:

• Apex 300

• AC200L

• AC200MAX

• AC300

• AC500

This compatibility allows for incredible scalability. For example, you can connect up to 6 B500K or 6 B300K batteries to a single Apex 300 power station, creating a massive energy reserve tailored to your exact requirements.

4. Portability: Power on the Move vs. Power at Home

Your intended use case—stationary or mobile—will heavily influence your choice, and the weight of each battery is a key factor.

• The B500K weighs 45 kg, making it better suited for stationary setups like a home backup system, where it can be installed once and left in place.

• At 29.5 kg, the B300K is a full 15.5 kg lighter. This significant weight difference makes it far more manageable for a single person to lift into an RV or carry to a worksite, a key advantage for mobile power needs.

5. Standalone Functionality: Quick Charge or Ecosystem Hub?

Both batteries can function independently of a main power station, but they do so in different ways.

• The B300K features a built-in 12W USB-A port, transforming it into a convenient, grab-and-go standalone power source for charging small devices like phones and tablets without any extra components.

• The B500K does not have built-in output ports. However, it can be used as an independent power source by pairing it with other BLUETTI ecosystem components, such as the Hub D1, to power your DC devices directly.

Apex 300 + Expansion Battery System Estimated Runtime Table

The Apex 300 offers 2,764.8Wh of base capacity and 3,840W of output power. When paired with expansion batteries, your total system capacity and runtime increases dramatically:

Which Expansion Battery is Right for You?

To make the right choice, identify which of these user profiles best describes your needs.

You should choose the BLUETTI B500K if:

• You are building a robust home backup system and maximum capacity is your top priority.

• Your power station will be mostly stationary, and you don't need to move the batteries often.

• You want the largest single-battery capacity available to minimize the number of units in your setup.

• You already own or plan to invest in the BLUETTI ecosystem, like the Hub D1, for DC power needs.

You should choose the BLUETTI B300K if:

• Portability matters to you; you need to move your power system for camping, RVing, or work.

• You value the highest possible cycle life (6,000+) for intensive, daily use over many years.

• You want the simple convenience of a built-in USB-A port for quick, standalone charging without extra accessories.

• Your budget is a consideration, and its capacity is more than sufficient for your planned needs.

Conclusion

Ultimately, the choice between the B500K and the B300K comes down to your unique energy needs. The B500K stands out for its immense capacity, making it the king of stationary home backup. The B300K offers a brilliant balance of substantial power, greater portability, and an exceptional cycle life for the most demanding users.

Both are outstanding, long-lasting LiFePO₄ batteries that will significantly enhance any compatible BLUETTI power system. The right choice is the one that aligns with your personal power goals and lifestyle.

Explore the B500K and B300K expansion batteries on our website today and take the next step in your energy independence.