Runtime estimates are easier when you understand watts, watt-hours, inverter losses, and battery reserves. This guide shows a practical method for sizing a power station before you buy.
Step One: List Device Wattage
Write down the running wattage of every device you plan to use. For appliances with startup surges, check both running and peak ratings.
Step Two: Estimate Daily Use
Multiply each device’s wattage by the number of hours it will run. Add the results together to get total watt-hours.
Step Three: Account for Losses
AC inverter systems are not 100 percent efficient. Multiply your total by about 1.15 to 1.25, then keep a reserve for unexpected use.
Example Calculation
A 60W laptop used for four hours consumes about 240Wh. Add a 20W light for five hours (100Wh), then allow for losses and reserve; a 500Wh class unit may be suitable.
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Frequently Asked Questions
Is advertised capacity usable capacity?
No. Usable energy is lower because of inverter losses, battery protection reserves, temperature, and the device’s own charging efficiency.
Does a bigger inverter mean longer runtime?
No. Inverter size determines the maximum load. Battery watt-hours determine runtime, while a larger inverter may use slightly more idle power.