Expansion Battery
Looking to extend your runtime for unexpected blackouts or off-grid adventures? BLUETTI expansion batteries offer a seamless, modular solution to multiply your power station capacity without investing in a completely new unit. Whether you need reliable home backup or portable extra power on the go, our scalable extra batteries integrate perfectly with your existing host power stations to deliver peace of mind when you need it most.
Expansion Battery
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PRODUCTS
BLUETTI Expansion Batteries: More Power, More Possibilities
A BLUETTI expansion battery is a dedicated add-on battery module designed to connect directly to compatible BLUETTI portable power stations, multiplying your total storage capacity without replacing your existing system. Whether you need more hours of home backup, longer runtime for off-grid living, or greater solar storage capacity to make the most of a time-of-use energy tariff, an expansion battery is the most cost-effective way to scale up your BLUETTI setup.
Both the B300K and B500K are compatible with the same range of BLUETTI power stations and can be stacked in multiple units to reach substantial combined capacities — the key difference is capacity per unit and cycle life, so you can choose based on how much storage you need and how long you want it to last.
B300K vs B500K: Which Expansion Battery Is Right for You?
| B300K | B500K | |
|---|---|---|
| Capacity per Unit | 2,764.8Wh | 5,120Wh |
| Cycle Life | 4,000+ cycles | 6,000+ cycles |
| Compatible Power Stations | Apex 300, AC500, AC300, AC200L, AC200MAX | |
| Best For | Flexible incremental expansion, lower upfront cost per unit | Maximum capacity per unit, longest lifespan |
Maximum Combined Capacity by Configuration
| Configuration | With B300K | With B500K |
|---|---|---|
| Apex 300 × 1 + Expansion × 6 | 19,353.6Wh | 33,484Wh |
| Apex 300 × 2 + Expansion × 12 | 38,707.2Wh | 66,969.6Wh |
| Apex 300 × 3 + Expansion × 18 | 58,060.8Wh | 100,454Wh |
| AC500 × 1 + Expansion × 6 | 16,588.8Wh | 30,720Wh |
| AC500 × 2 + Expansion × 12 | 33,177.6Wh | 61,440Wh |
| AC300 × 1 + Expansion × 4 | 11,059.2Wh | 20,480Wh |
| AC300 × 2 + Expansion × 8 | 22,118.4Wh | 40,960Wh |
| AC200L × 1 + Expansion × 2 | 7,577.6Wh | 12,288Wh |
| AC200MAX × 1 + Expansion × 2 | 7,577.6Wh | 12,288Wh |
Versatile Energy Storage for All Scenarios
Extended Home Backup
A single BLUETTI power station is already a capable home backup solution — but when a longer outage demands more, expansion batteries transform your system into a serious whole-home energy reserve. A single AC500 paired with six B500K units delivers 30,720Wh of combined storage — enough to run a full UK household for several days without any grid input. For homes on time-of-use tariffs, a higher total capacity also means more cheap off-peak electricity stored per cycle, increasing daily savings on Economy 7, Economy 10, or Octopus Agile.
Off-Grid Living & Van Life
For campervan conversions, off-grid cabins, and extended overlanding trips, continuous runtime is everything. An Apex 300 paired with B500K units scales to over 33,000Wh in a single-station configuration — enough to run a 12V fridge, lighting, cooking appliances, and device charging for extended periods between solar top-ups, making it a powerful foundation for full-time off-grid living.
Solar Storage Expansion
If you're already using BLUETTI with solar panels and finding your power station fills up before the day's generation is complete, an expansion battery gives that surplus energy somewhere to go. Rather than wasting excess solar generation, a larger combined capacity stores more of what your panels produce — reducing grid imports further and making your solar setup more effective year-round, including during the UK's longer summer days when generation peaks.
Standalone Power on the Go
Both the B300K and B500K include a USB-A output port, letting you charge phones and small devices directly from the battery module without connecting to a power station — a practical independent power source for travel, outdoor work, or keeping essentials running when the main unit is in use elsewhere.
What Makes BLUETTI Expansion Batteries Different
Automotive-Grade LiFePO₄ Chemistry
Both the B300K and B500K use automotive-grade lithium iron phosphate (LiFePO₄) cells — thermally stable, inherently non-combustible, and rated for thousands of charge cycles. The B300K is rated for 4,000+ full cycles and the B500K for 6,000+ cycles before dropping below 80% capacity, meaning even daily charging delivers well over a decade of reliable service. Both are safe to store and operate indoors without ventilation.
AI-BMS Battery Management
BLUETTI's AI Battery Management System actively monitors cell voltage, temperature, and charge state in real time — protecting against overcharge, over-discharge, short circuit, and thermal runaway. Predictive monitoring anticipates and prevents issues before they occur, extending both the safety and operational lifespan of your battery system across thousands of cycles.
Tool-Free, Hot-Swappable Connection
Connecting either expansion battery to a compatible power station requires no tools and no technical knowledge. Simply plug in and the system recognises the additional capacity automatically — on supported configurations you can connect expansion batteries while the power station is running, with no interruption to connected devices.
Modular & Scalable by Design
Rather than replacing your existing power station when your energy needs grow, BLUETTI's modular expansion system lets you add capacity incrementally — one battery at a time. Both the B300K and B500K support multi-unit stacking across all compatible power stations, scaling from a practical home backup starting point all the way up to 100kWh+ configurations for serious off-grid or commercial energy storage needs.
Your Questions About Expansion Battery, Anwsered.
- Do BLUETTI expansion batteries work as standalone power sources?
- Yes. Both the B300K and B500K include a USB-A output port, allowing you to charge phones, tablets, and small devices directly from the battery module without connecting it to a power station. This makes them useful as an independent power source for travel or outdoor use, and means the battery remains functional even if used away from the main unit.
- Is it better to buy a larger power station or add an expansion battery?
- In most cases, adding an expansion battery to your existing power station is the more cost-effective approach — you retain the inverter, output ports, and smart features of your current unit while adding only the storage capacity you need. Buying a new, larger power station means paying for a second inverter and control system you may not need. The exception is if your current power station's output wattage is insufficient for your appliances — in that case, a higher-output power station would be needed regardless of battery capacity. If your existing unit already handles your load comfortably, an expansion battery is almost always the better value choice.
- How many expansion batteries can I connect to my BLUETTI power station?
- This depends on your power station model. The Apex 300 supports up to six expansion batteries per unit — reaching 19,353.6Wh with B300K units or 33,484Wh with B500K units in a single-station configuration, and scaling further with multiple Apex 300 units. The AC500 supports up to six expansion batteries, the AC300 up to four, and the AC200L and AC200MAX up to two each. Multiple power stations can also be combined alongside expansion batteries for very large capacity configurations — up to 100,000Wh+ in a fully stacked setup.
- Is it safe to leave the battery expansion pack connected all the time?
- Yes, absolutely. BLUETTI’s intelligent BMS (Battery Management System) actively monitors voltage, current, and temperature across both the host unit and connected expansion packs. It automatically balances the cells and stops charging when full, making it perfectly safe for long-term home backup setups.
- Can I connect an expansion battery while my power station is running?
- Yes — BLUETTI expansion batteries support hot-swappable connection on compatible power station configurations. You can add a B300K or B500K while the power station is actively powering connected devices, with no interruption to output. The system recognises the additional capacity automatically with no tools or technical setup required.
- What is the difference between the B300K and B500K expansion batteries?
- Both the B300K and B500K are compatible with the same range of BLUETTI power stations and can be stacked in multiple units to reach large combined capacities. The key differences are capacity and cycle life: the B300K offers 2,764.8Wh per unit with a 4,000+ cycle rating, while the B500K offers 5,120Wh per unit with a 6,000+ cycle rating.
