BLUETTI B300K Expansion Battery | 2,764.8Wh

BLUETTI B300K Expansion Battery | 2,764.8Wh

Turn a power station into a home backup system

A 2,000Wh power station gets you through an evening. It doesn’t get you through a Northland storm that takes the lines down for two days.

The BLUETTI B300K is the module that closes that gap. It adds 2,764.8Wh of LiFePO₄ storage to a compatible BLUETTI power station more than doubling most setups without replacing anything you already own. Your existing station keeps doing the inverting and the switching. The B300K just makes sure it doesn’t run dry.

2,764.8Wh what that covers in a real blackout

At roughly 85% system efficiency you have about 2,350Wh of usable energy to work with. Here’s what that means in practice. These are planning estimates, not guarantees actual figures depend on your appliances, ambient temperature and how hard your fridge is working.

Run the fridge, the freezer, the internet and the lights together and you’re looking at comfortably over a day of normal life. Most NZ outages don’t last that long.

Check compatibility before you order

This is the part worth getting right, because an expansion battery that doesn’t match your station is an expensive doorstop.

You can also stack multiple B300K modules, and mix them with older B300 units on supported stations, so an existing multi-battery setup can be extended rather than replaced. If you’re running an AC500 with six modules, total capacity climbs to roughly 16,589Wh.

Not sure what you’ve got? Send us your model number and we’ll confirm before you buy.

Charged through your power station, from any source

The B300K doesn’t have its own charging inputs it draws power through the host station, which means it charges from whatever your station is connected to. Wall power, solar, vehicle, or generator. Whatever’s feeding the station feeds the battery.

That’s simpler than it sounds in practice. Plug in the cable, and your solar array now fills 2,764.8Wh more storage without any extra hardware. Paired with an AC300 or AC500, BLUETTI rates the module at 80% charge in about 45 minutes on a fast input.

The one thing to know: the B300K can’t be charged on its own. It needs to be connected to a compatible station to take a charge.

Standalone USB when it’s disconnected

The module has a built-in 12W USB-A port, so it isn’t dead weight when it’s detached from your station. Phones, tablets, torches, a fan the everyday small stuff keeps charging straight off the battery.

Useful for a bach or a boat where the power station travels but the expansion battery stays put.

4,000+ cycles, and built to sit in a garage for a decade

BLUETTI rates the B300K’s automotive-grade LiFePO₄ cells at more than 4,000 charge cycles. Cycle it daily and that’s a decade of service before capacity degradation becomes something you’d notice.

The rest of the build matches that intent: an aluminium casing, an active cooling fan, and an AI-driven battery management system handling cell balancing, temperature and current. LiFePO₄ is also the more thermally stable lithium chemistry, which is why it’s the standard for storage that lives inside homes rather than in a shed.

Worth knowing for South Island buyers: like any lithium battery, avoid charging it below freezing. Discharging in the cold is fine.

29.5kg plan where it lives

At 29.5kg this is a two-person lift, or a one-person lift if you’re careful and it isn’t going far. It’s designed to stay put rather than travel between campsites.

The upside is that it wall-mounts, which keeps a garage floor clear and puts the battery somewhere sensible next to your switchboard. For a van or motorhome, plan the mounting point and the weight distribution before you commit.

Who this is for

• Home backup — households in outage-prone areas wanting a full day or more of essentials, not just an evening
• Rural and lifestyle blocks — where the water pump stopping matters as much as the lights
• Off-grid cabins and baches — paired with solar for genuine independence
• Motorhomes and long-stay vans — fixed installation, mains-free living
• Existing BLUETTI owners — the cheapest way to double a system you already trust

Key specifications