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Cab Tools

Heated jacket runtime calculator

Cold steals battery capacity. Enter your pack and heat setting — see honest runtime at −20°C (-4 °F) before you are counting on it.

Heated Jacket Runtime at −20°C (-4 °F)

Milliamp-hours, printed on the pack. Common heated-apparel packs: 5,000–20,000 mAh.

Pack voltage

Heat setting

Follows the heat setting above, but stays editable. Typical 7.4 V jackets: low 5–8 W, medium 8–14 W, high 14–22 W — your manual is the source of truth.

Air temperature-20°C (-4 °F)

Lithium packs deliver less energy as it gets colder — the calculator derates capacity accordingly (100% at +10°C (50 °F) down to 65% at -30°C (-22 °F)).

Estimated runtime
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Deep-cold rule: keep a spare pack warm — inside pocket, not on the dash. A frozen spare starts the night at a disadvantage.

Won’t last half a shift. Carry a charged spare pack or plan a recharge stop.

  • Cold-capacity numbers are planning estimates, not lab measurements — real packs vary with age and chemistry.
  • Most jackets cycle on a thermostat, so real-world runtime often beats this continuous-draw math.
  • A heated jacket warms you, not the cab — personal heat for pre-trips and fuel stops, not an idle replacement.
  • Keep a spare pack warm in an inside pocket. A frozen spare starts the night at a disadvantage.