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Bluetti AC300 + B300 sizing guide
A modular 3 kW system with a sub-20 ms UPS switch — toward whole-home with a transfer switch. Here's exactly what it runs, how long, and which outages it covers — computed, not marketed.
Modular; expandable to 12.3 kWh, 24/7 UPS · 116 lb · 7× AC (incl. 30 A), USB-A/C · expandable with add-on batteries.
What the AC300 + B300 runs — and for how long
| Appliance | Running | Runs it? | Approx. runtime |
|---|---|---|---|
| Refrigerator (modern) | 150 W (1,200 W surge) | yes | ~53 h |
| Chest Freezer | 100 W (1,000 W surge) | yes | ~79 h |
| CPAP Machine (no humidifier) | 40 W | yes | ~69 h |
| CPAP with Heated Humidifier | 60 W (95 W surge) | yes | ~58 h |
| Oxygen Concentrator | 350 W (600 W surge) | yes | ~7.9 h |
| Space Heater (1500 W) | 1,500 W | yes | ~1.8 h |
| Window AC (8,000 BTU) | 715 W (1,250 W surge) | yes | ~5.5 h |
| Window AC (12,000 BTU) | 1,100 W (1,800 W surge) | yes | ~3.6 h |
| Gas Furnace Blower (1/2 HP) | 800 W (2,350 W surge) | yes | ~6.9 h |
| Microwave (1000 W cooking) | 1,200 W | yes | ~2.3 h |
| Sump Pump (1/3 HP) | 800 W (1,500 W surge) | yes | ~17 h |
| Sump Pump (1/2 HP) | 1,050 W (2,150 W surge) | yes | ~13 h |
| Well Pump (1/2 HP) | 1,000 W (2,100 W surge) | yes | ~18 h |
Runtime uses each load's duty-weighted average draw against 90% of the rated capacity — conservative on purpose. Cyclic loads (fridges, pumps) run far longer than running-watts × capacity would suggest.
Outages the AC300 + B300 covers
Common questions
What can the Bluetti AC300 + B300 run?
With 3,000 W of continuous output and a 6,000 W surge rating, the Bluetti AC300 + B300 runs refrigerator (modern), chest freezer, cpap machine (no humidifier), cpap with heated humidifier, oxygen concentrator, space heater (1500 w), and more. Its 3,072 Wh battery sets how long: a fridge for roughly a day, a CPAP for several nights.
How long will the Bluetti AC300 + B300 run a refrigerator?
A modern refrigerator averages about 53 W (it cycles ~35% of the time), so the Bluetti AC300 + B300's 3,072 Wh runs one for roughly 53 h before recharging.
Specs: Manufacturer published specifications (approximate; confirm on the current product page) (compiled 2026-06-15). Informational only — a computed sizing estimate from published appliance-wattage charts and manufacturer station specs. It is not an electrical guarantee. For hardwired or whole-home backup, transfer switches, or any permanent install, consult a licensed electrician.