How long can the Goal Zero Yeti Pro 4000 run a CPAP machine?
10.6 dayswell beyond what you asked for
Formula: (4kWh × 0.85 inverter efficiency) ÷ 0.32 kWh/day = 10.6 days. At continuous 40 W draw (no duty cycle), about 3.5 days.
Appliance
CPAP machine · 40 W / 60 W surge
Battery (base)
4kWh · 3.6kW / 7.2kW surge
Runtime Quick-Check
Runtime Quick-Check
Pick a battery and an appliance — see days of runtime after the 0.85 inverter derate.
10.6 days
Formula: (3993 Wh × 0.85) ÷ 0.32 kWh/day = 10.6 days. Continuous draw ≈ 3.5 days at full load.
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