A:Answer It depends on how much power the fan consumes. Suppose you are running a 100 Watt fan using one of the 120VAC outlets on the unit. Assuming the battery is fully charged and it has not lost any capacity due to many discharge and charge cycles, or due to having been left in a discharged state for a long period of time, it will provide 80 Ampere-hours (A-hr) at 12V if the less-than-100% efficiency of the built-in inverter is ignored. Converting the 80 A-Hr at 12V to 120V gives 8 A-Hr at 120V (80 times 12 divided by 120). A 100 Watt fan will draw 100/120=0.83 A at 120V, so it would run for 8/0.83= 9.6 hours. In reality, the actual run time will be less because of the losses in the inverter and the internal losses in the battery, so a realistic figure is probably 7 to 8 hours. Using a 12V fan instead of one that runs off 120VAC would eliminate the inverter loss and give a longer run time. Also, the run time will scale inversely with the power rating of the fan, so for example, a 50 Watt fan would run twice as long. I hope this helps answer your question.
