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BLUETTI · BLUETTI B300K EXPANSION BATTERY
FRONT
BACK
PORTS
SCALE
IN USE
WattBunker Lab Score · 8.8 / 10
Capacity vs spec 94
Close to rated capacity in real-world testing
Recharge speed 91
Fast 0→80% on AC for its class
Inverter stability 88
Held nominal load without faults
Noise (1m) 84
Fan audible under high load
Build quality 86
Rigid chassis, ports recessed
In Stock
Bluetti

Bluetti B300K Expansion Battery

2,764.8 Wh LFP expansion pack for Bluetti's AC200L, AC200MAX, AC300, AC500, and AC200PL stations — 4,000+ cycle life (15% longer than the older B300) and a built-in 12W USB-A port that lets it pinch-hit as a standalone power bank. Pair one with an AC200L and you're at ~4.8 kWh on the bench.

4.7 (260) 4.7 out of 5 (260 reviews)
2,765
Wh
65
lb
4,000
cycles
  • 2,764.8 Wh LFP cells, 4,000+ cycles to 80% capacity
  • Backward + forward compatible: AC200L, AC200MAX, AC300, AC500, AC200PL
  • Built-in 12W USB-A port — works standalone as a (very heavy) power bank
  • Recharges via the host station — wall, solar, car, or generator inputs all pass through
  • Ships with the P090A expansion cable for AC200L / AC300 / AC200MAX
  • 4-year warranty

The good and the bad

✓ Pros
  • 15% longer cycle life than the older B300 — 4,000 cycles is class-leading for an expansion pack
  • One pack works across five Bluetti hosts past and future — investment is portable across upgrades
  • Built-in USB-A on the pack itself means it isn't a brick when the host station isn't around
  • Pairing with an AC200L pushes a $899 host into 4.8 kWh of LFP storage for under $2,000 total
✕ Cons
  • Useless on its own for AC loads — needs a compatible Bluetti host to drive 120V appliances
  • 65 lb / 20.5 × 12.6 × 10.3 in — single-person carry on flat ground only, no chance of stairs
  • On the AC300, it can only be mixed with the original B300 — the rest of the lineup is single-flavor
  • 15W self-consumption pulls ~360 Wh/day idle if you leave the host AC output armed
Who this is for

If this is you, you're in the right place

  • AC200L owner who hit the wall on capacity

    Pairs natively with the AC200L for ~4.8 kWh total. The host's ports drive the load; the B300K just stores more.

  • Bluetti-ecosystem upgrader

    Compatible with AC200L, AC200MAX, AC300, AC500, AC200PL — past, present and future. The pack survives host upgrades.

Who should skip this

If this is you, keep shopping

  • First-time buyer with no host

    Useless on its own for AC loads. You need a compatible Bluetti station to drive 120V appliances.

  • Stair-carrier

    65 lb, single-person on flat ground only. Plan a permanent home for it.

Real-world runtime

How long it lasts on real loads

Estimates apply 85% inverter efficiency to the rated capacity. Real-world numbers vary with temperature, battery age, and appliance duty cycle.

Load Watts Hours Note
Adds to AC200L total: Energy Star fridge 150W 18 h host + B300K combined runtime
Adds to AC200L total: CPAP w/ humidifier 60W 46 h
USB-A standalone (12W) phone charging 12W 230 h pack acting as solo power bank

Full specs

Battery

Chemistry LFP
Capacity 2,765Wh
Cycles to 80% 4,000

Physical

Weight 65lb
Verdict
8.8
OUT OF 10 · GREAT BUY

Bluetti Bluetti B300K Expansion Battery — the verdict

2,764.8 Wh LFP expansion pack for Bluetti's AC200L, AC200MAX, AC300, AC500, and AC200PL stations — 4,000+ cycle life (15% longer than the older B300) and a built-in 12W USB-A port that lets it pinch-hit as a standalone power bank. Pair one with an AC200L and you're at ~4.8 kWh on the bench.

Check on Amazon
Versus the competition

Where it wins and loses against the alternatives

Bluetti
Bluetti AC200L
Price: $899 Wh: 2,048 Lab: 8.9/10

The natural host. AC200L + B300K = 4.8 kWh of LFP at $1,998 total — cheaper per Wh than any 4-5 kWh standalone in this list.

See review →

FAQ

How long does the Bluetti B300K Expansion Battery run a typical refrigerator?
A modern A++ fridge averages ~150 W. With 2765 Wh of usable battery, that's roughly 18 hours of continuous runtime before it depletes.
Is the Bluetti Bluetti B300K Expansion Battery worth it versus competitors?
Bluetti competes directly with EcoFlow, Bluetti and Anker in this segment. The Lab Score of 8.8 suggests a solid unit at this price point. Cross-shop on /compare with your second pick.
Is it LFP or NMC?
The Bluetti B300K Expansion Battery uses LFP cells. LiFePO₄ delivers more cycles but weighs more.

Compared to alternatives