I got this $20 Ryobi 4 inch 18 volt battery powered fan at Home Depot. RYOBI ONE+ 18V Cordless 4 in. Clamp Fan (Tool Only)-PCF02B - The Home Depot It is great for working on the car, additional cooling while driving or waiting in the car with the windows down. On a long trip in excessive heat, it could be placed under the rear seat to direct additional air to the HV fan intake. With a 3AH battery at low speed, I ran it continuously, and it lasted more than 18 hours, before it automatically cut off to keep the battery safe from draining any more. I'm impressed.
