Free tool
Winter Power Station Runtime Calculator
How long will a power station run your furnace fan, fridge and lights in a winter outage? Free calculator that accounts for cold batteries.
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Pick a power station, tell the calculator where the battery will sit, and tick the things you need to keep running. Results update as you type.
How to get accurate numbers
The defaults above are typical values, not your values. Two minutes of checking will make the estimate much better:
- Furnace blower: look for the sticker inside the furnace’s front panel. It lists the blower motor’s amps. Multiply amps by 120 to get watts (a 4 A motor ≈ 480 W). If the label says “ECM” or “variable speed,” your blower probably draws far less.
- Fridge: the sticker inside the door or on the back lists amps or watts. That number is the compressor’s peak; it only runs part of the time, which is what the “% on” column captures.
- Everything else: the power brick or nameplate usually lists watts or amps.
Why the battery’s temperature changes everything
Lithium batteries give back less energy when they’re cold. A power station sitting in a −20°C garage might deliver only around two-thirds of what it would indoors — and some units stop working entirely below their rated minimum. Jackery, for example, rates the Explorer 1000 v2 to operate down to −10°C and to charge only at 0°C or warmer.
The practical rule: keep the power station in the heated part of the house and run a heavy-duty extension cord to whatever needs power.
What the calculator doesn’t know
It can’t account for your battery’s age, how warm the unit was before the outage, or startup surges from motors. Treat the result as a planning estimate and build in a margin — if the calculator says 10 hours, plan for 7 or 8.
Want the full picture on cold limits for each model? See the cold-weather spec database.
Frequently asked questions
How long will a 1,000 Wh power station run a furnace?
It depends mostly on the blower motor. A furnace fan drawing around 450 W that runs half the time averages about 225 W, so a 1,000 Wh unit kept indoors lasts roughly 3 to 3.5 hours after inverter losses. Newer ECM blower motors draw far less and can stretch that considerably. Use the calculator with your furnace's nameplate numbers.
Why does cold weather reduce runtime?
Lithium batteries deliver less of their stored energy when cold, because the chemical reactions inside slow down. The energy isn't destroyed — a battery that warms back up recovers most of it — but you can't use it while it's cold. That's why keeping the power station inside the heated part of the house matters.
Can I leave a power station outside or in the garage during an outage?
Check the manufacturer's operating temperature range first. Some units are rated to run only down to −10°C, and most lithium batteries shouldn't be charged below 0°C. Keeping the unit indoors and running an extension cord to what you need is the safer approach.
Is it safe to power my furnace with a portable power station?
Gas furnaces need electricity for the blower and controls, and many people run them from a power station during outages. How you connect it matters: hard-wired furnaces need a proper transfer switch or inlet installed by a licensed electrician. Never backfeed a house through an outlet.