Running watts are what a device draws once it is going; surge (start-up) watts are the brief peak when its motor or compressor
starts, 2.6 times the running draw for a typical sump pump. A power station has to clear both: its
continuous rating for the running watts, its surge rating for the start. Of the 55 units with an AC outlet, 44 can start a full-size fridge and 36 a 3/10 HP submersible sump pump.
An explanation, not a measurement: a compressor or motor peaks for a fraction of a second as it starts, then settles to its running draw. The start must stay under the station's surge rating and the running draw under its continuous rating.
Which devices surge
Motors and compressors do: refrigerators and freezers, sump and well pumps, air conditioners, power tools, blenders. Starting a
motor from standstill takes several times its running current for a moment. Heating elements do not: a space heater, a kettle,
a coffee maker, a hair dryer or an electric blanket draws about the same from the first second, so its label wattage is all you check (a 1,500 W heater needs 1,500 W continuous). Electronics such as laptops, TVs,
routers and phone chargers draw a small inrush that any station absorbs.
Reading a power station's two numbers
The continuous (rated) output is what the inverter can deliver indefinitely; the surge (peak) figure is what it can
deliver for a moment, usually seconds or less, which is what a motor start needs. 48 of the 55 tracked units with an AC
outlet publish a surge figure, and at the median it is 2 times the continuous rating. For the 7 that publish none,
this site checks a start against the continuous rating alone, which can rule out a unit that would in fact start the device, never the reverse.
Some makers also advertise a "lifting", "X-Boost" or "power lifting" figure above the continuous rating. That mode lowers the voltage so a
heating element runs slower instead of tripping the inverter; it does not help a motor start, and this site never counts it as output.
Where the start-up figure comes from
The device table gives each figure with its source: a maker's label, a manual or a utility's published table. Your own appliance may differ, so the
best number is on its label or in its manual: look for "LRA" (locked-rotor amps) on a compressor, multiply amps by 120 for watts, and treat that as the
worst case. If an air conditioner or pump starts too hard for any unit you would carry, a soft-start kit lowers the peak.
What it takes to start each motor in the device table
Running and start-up watts from the device table; units that clear both, of 55 with an AC outlet
Starting is only half of it: the battery then decides the hours. Each device's page gives its hours on every unit, and the calculator checks the start of the largest motor in your own list.
Questions buyers ask
Will a 1,000 W power station run a refrigerator?
Usually it runs one, but whether it starts one depends on its surge figure: a full-size fridge peaks at about 1,300 W for a moment. Units rated 1,000 W continuous with a 2,000 W surge start it; one without a published surge figure may not. The refrigerator guide names the units that clear one, two and three days.
Do I add up the surge watts of everything I plug in?
No. Add the running watts of everything that runs at once, then add the largest motor's extra start-up watts (its start-up figure minus its running figure), because two motors rarely start in the same instant. That total must stay under the surge rating, and the running total under the continuous rating.
What happens if the start is too big?
The inverter protects itself and cuts the output, usually showing an overload warning; you reset it and unplug something. The protection is there so nothing is damaged, but the device does not start.
Does a space heater surge?
No. A heating element draws its label wattage from the first second, so a 1,500 W heater needs 1,500 W of continuous output and empties a 1 kWh unit in well under an hour. The space heater page gives the hours on every unit.
