Firstly, you need to find out the operating power of your device (measured in watts). If the operating power of your device does not exceed the output power of the power station AC port, you can safely use the power station to run/charge/power it. For instance, the CTECHi power station GT500 is capable of running AC devices at 110V that require less than 500W. After that, you can also calculate the time required by the device to fully charge with the help of the following formula: Working time = CTECHi 's (G240n, G320n, GT500, GT1200, ST2000~) Watt-Hours * 0.85 / operating power of your device. Example: Suppose your gadget consumes 60W of electricity (it may be a box fan or anything else), and you want to use the CTECHi 's GT500 to power it. In that case, according to the formula discussed above 518Wh*0.85/60w = Roughly 7 hours of working time. Please keep in mind that the actual power consumption might be lesser/greater depending on several factors. If you still haven't found a satisfactory answer, you can submit your queries directly on the product page, drop us an email at Sevice@ctechi.com or directly send us a message, and we will get back to you as soon as possible, and we'll be glad to guide you further.