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How long common devices run on a power station
Each device on its own, with a 10% reserve at 20 °C or warmer. Phones and LED lights at 10 W are treated as DC loads, the rest as AC.
| Device | 300 Wh | 1,000 Wh | 2,000 Wh |
|---|---|---|---|
| Phone or LED light (10 W) | 25 h 39 min | 3 days 14 h | 7 days 3 h |
| Fan (25 W) | 10 h 16 min | 34 h 12 min | 2 days 20 h |
| CPAP machine (40 W) | 6 h 25 min | 21 h 23 min | 42 h 45 min |
| TV (40 W) | 5 h 44 min | 19 h 8 min | 38 h 15 min |
| Laptop (60 W) | 3 h 49 min | 12 h 45 min | 25 h 30 min |
| Mini fridge (60 W, runs 40%) | 9 h 34 min | 31 h 53 min | 2 days 16 h |
| Electric kettle (1,000 W) | 14 min | 46 min | 1 h 32 min |
| Space heater (1,500 W) | 9 min | 31 min | 1 h 1 min |
Look at the last two rows: heating appliances use as much power in an hour as a laptop does in half a day. They also tend to exceed the output rating of small stations.
How the runtime is calculated
- Usable energy (Wh) = capacity × (1 − reserve) × a cold-weather factor. The factor is 100% at 20 °C or above, 95% at 10–19 °C, 85% at 0–9 °C and 70% below 0 °C. It is a rough allowance, not a measurement.
- Average load (W) = for each device, watts × quantity × % of time, then AC devices are divided by 0.85 and DC devices by 0.95 to cover conversion losses.
- Runtime (hours) = usable energy ÷ average load. Every ticked device is assumed to run at the same time.
- Overload check = total rated watts of all ticked AC devices compared with the AC output rating you enter. It uses full watts, since devices can switch on together.
It does not model start-up surges, inverter idle draw or battery ageing, so keep a margin.
Using it anywhere in the world
- Capacity works in Wh or Ah. Wh = Ah × volts.
- Temperature works in °C or °F. The page picks one from your browser language and you can switch it.
- Numbers use your own region’s separators.
- Appliances differ by country. Kettles, heaters and hair dryers on 230 V circuits often draw 2,000–3,000 W, more than typical 120 V versions. Always check the label on your own device.
Common mistakes
- Treating the label capacity as usable. After inverter loss and a reserve, expect roughly 75–85% of it at the AC socket.
- Charging a laptop through the AC socket. A USB-C or DC output skips the inverter and gets more minutes from the same battery.
- Plugging in heating appliances. They drain the battery in under an hour and can trip the output limit.
- Forgetting start-up surges. Motors, pumps and fridge compressors pull more for a moment, so leave headroom in the output rating.
- Counting a fridge as always on. Use the % of time instead of 100%.
- Draining to zero. A reserve usually helps the battery last longer.
Common questions
How long will a power station run a mini fridge?
A 1,000 Wh power station runs a 60 W AC mini fridge for about 32 hours when the compressor is on 40% of the time. Compressors cycle on and off, so the average draw is far lower than the label. In hot weather the fridge runs more often, so enter a higher percentage.
Why does my power station run for less time than its label suggests?
The label shows the energy stored in the battery, not what reaches your device. The AC inverter loses about 15% as heat, and it also draws power just by being switched on. Many stations stop at a reserve level, and cold weather cuts the usable capacity. Using the DC, USB or USB-C outputs for phones and laptops avoids the inverter loss.
How do I convert amp-hours (Ah) to watt-hours (Wh)?
Multiply amp-hours by the battery voltage. A 100 Ah battery at 12.8 V holds 1,280 Wh. Choose Ah in the calculator and enter the voltage, and it does this for you.
Can a power station run a kettle, hair dryer or space heater?
Only if its AC output rating is higher than the appliance’s power, and the battery will drain quickly. A 1,000 W kettle empties a 1,000 Wh station in about 46 minutes, and a 1,500 W heater in about 31 minutes. In countries with 230 V outlets, kettles and heaters of 2,000 to 3,000 W are common, which is above the output of many portable stations.
My appliance lists amps, not watts. What do I enter?
Multiply volts by amps. A device marked 0.5 A at 230 V uses about 115 W, and at 120 V the same current is 60 W. Open the amps helper under the device list and pick your country’s outlet voltage. For motors the real power can be lower than volts times amps, so a watt meter is more accurate.
Does cold weather reduce runtime?
Yes. Lithium batteries deliver less energy when cold, and many stations will not charge below freezing. The calculator uses a rough allowance of 100% at 20 °C or above, 95% from 10 to 19 °C, 85% from 0 to 9 °C and 70% below 0 °C. Keeping the station indoors or insulated helps.
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