How long can the Tesla Powerwall 3 run a Space heater?
15.3 hours
Formula: (13.5kWh × 0.85 inverter efficiency) ÷ 18 kWh/day = 15.3 hours. At continuous 1500 W draw (no duty cycle), about 7.7 hours.
Appliance
Space heater · 1500 W / 1500 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.
15.3 hours
Formula: (13500 Wh × 0.85) ÷ 18 kWh/day = 15.3 hours. Continuous draw ≈ 7.7 hours at full load.
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