Yes — and it will flatten the battery faster than almost anything else you can plug in. A 1,500 W heater empties a 1 kWh power station in about 34 minutes.
Drain table (1,500 W heater on full; 750 W on low)
Power station
Full power lasts
Low (750 W) lasts
300 Wh
10 min
0.3 h
500 Wh
17 min
0.6 h
1,000 Wh
34 min
1.1 h
2,000 Wh
68 min
2.3 h
3,600 Wh
122 min
4.1 h
Includes the 0.85 inverter efficiency factor. Real results vary slightly with battery age and temperature.
Quick answers
Why is electric heat so brutal on batteries?
Resistive heating converts electricity to heat 1:1 — there's no efficiency to find. 1,500 W is 1,500 W, and a 1 kWh battery holds… 1 kWh.
What should I use for heat in an outage instead?
Blankets and layers first; a propane heater rated for indoor use (with ventilation); a diesel heater in vans; or a fuel generator if heating is non-negotiable. Save the battery for fridge, light, and comms.
What about a heated blanket instead?
Much better: 50–100 W instead of 1,500 W. A 1 kWh station runs a heated blanket all night with room to spare.