How long can the Tesla Powerwall 3 run a CPAP machine?
35.9 dayswell beyond what you asked for
Formula: (13.5kWh × 0.85 inverter efficiency) ÷ 0.32 kWh/day = 35.9 days. At continuous 40 W draw (no duty cycle), about 12 days.
Appliance
CPAP machine · 40 W / 60 W surge
Battery (base)
13.5kWh · 11.5kW / 11.5kW surge
Runtime Quick-Check
Runtime Quick-Check
Pick a battery and an appliance — see days of runtime after the 0.85 inverter derate.
35.9 days
Formula: (13500 Wh × 0.85) ÷ 0.32 kWh/day = 35.9 days. Continuous draw ≈ 12 days at full load.
Nearest alternatives
Running more than one device?
Open sizing wizard