Guide · 2026-11-11
How to read a power station label
The two numbers that matter first are watt-hours and continuous AC watts. Watt-hours are the tank. Continuous watts are how wide the tap is allowed to open. A surge or boost figure is a short permission, not a second tank.
Watt-hours, not a runtime
A label that says 1,024 Wh does not say "a fridge for 20 hours." Divide watt-hours by the load in watts and you get hours only if every watt-hour leaves the battery and the load never changes. An AC outlet passes through an inverter. If the maker does not print that inverter's efficiency, RunTime uses 85% and says so. That 85% is the same planning assumption as the PC UPS calculator. It is not a lab result for your Jackery or EcoFlow.
Continuous, surge, and boost
Continuous AC watts are the number to compare with a steady load. Surge, peak, X-Boost, Power Lifting, and SurgePad are different words for a higher short limit. A heater may be allowed there. A device that needs its full watts all evening may not. If the load is above the continuous rating, RunTime still shows the hour math and then flags the limit.
AC and DC are different taps
A USB-C port or a 12 V car port does not use the AC inverter. The watt limit is the port's own rating, often printed as volts times amps. A CPAP with a 24 V supply does not automatically belong on a 12 V car port. Match the voltage the device asks for.
Why the box's appliance chart runs long
Marketing runtimes often assume a small steady load and a fresh battery at room temperature. A fridge compressor starts hard, runs, then rests. Age, cold, and a half-charged pack all shorten the night. Read the watt-hour figure, read the continuous watt figure, and put your own load into the calculator.