How long can the Bluetti AC300 + B300K run a CPAP machine?
7.3 dayswell beyond what you asked for
Formula: (2.8kWh × 0.85 inverter efficiency) ÷ 0.32 kWh/day = 7.3 days. At continuous 40 W draw (no duty cycle), about 2.4 days.
What if you add a battery? The AC300 + 2× B300K config jumps to 5.5kWh — roughly 14.7 days on a CPAP machine.
Appliance
CPAP machine · 40 W / 60 W surge
Battery (base)
2.8kWh · 3kW / 6kW surge
Some links may be affiliate links. GridMatch may earn a commission if you buy through them, at no extra cost to you.
Runtime Quick-Check
Runtime Quick-Check
Pick a battery and an appliance — see days of runtime after the 0.85 inverter derate.
7.3 days
Formula: (2765 Wh × 0.85) ÷ 0.32 kWh/day = 7.3 days. Continuous draw ≈ 2.4 days at full load.
Nearest alternatives
Running more than one device?
Open sizing wizard