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Portable Power Station Runtime Calculator

Estimate runtime for portable power stations based on connected load, efficiency losses, and environment.

Power Station

Device Load

Environment

Optimal: 15-35°C. Performance decreases outside this range.

Conservative buffer for unexpected power draws and battery aging.

Portable power station runtime formula and worked example

Formula

runtime = (capacity Wh × inverter efficiency × temperature factor ÷ load W) × discharge-rate factor × (1 − safety margin)

where the temperature factor is 1.0 between 15–35 °C, dropping to 0.715 at −35 °C (the 50% floor is reached only below about −73 °C); discharge-rate factor is 1.0 low / 0.95 medium / 0.90 high; safety margin defaults to 10%

Worked example

A 1,024 Wh portable power station runs a full-size refrigerator drawing about 100 W continuously through its 90%-efficient inverter at room temperature (20 °C) at a medium discharge rate, with the default 10% safety margin.

  1. Usable energy: 1,024 Wh × 0.90 inverter efficiency = 921.6 Wh (no temperature derating at 20 °C)
  2. Runtime before adjustments: 921.6 Wh ÷ 100 W = 9.22 hours
  3. Medium discharge factor: 9.22 h × 0.95 = 8.76 hours
  4. Safety margin: 8.76 h × 0.9 = 7.9 hours

Result

The station runs the 100 W refrigerator for about 7.9 hours — meeting the 6-hour goal.

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