I'm charging off a 20 amp circuit. I will boost to 20 amp and see what happens. I also plan to add more solar. Just wanted something to keep batteries from completely discharging . Worked for that purpose with everything disconnected. I considered the smaller inverter option as well. The fan I'm using is a window fan. I have a fantastic fan as well. Thought the stand alone would use less juice and pull more air. Today the batteries showed 12.5 amps. After running the fan for 3 hrs Its 12v. I'll charge overnight and see if I can get over 14v.sorry for the double post