Prior to the analog v. digital signal change I used a Vector portable TV for entertainment and NOAA severe weather warnings (which I still use)during hurricane events. Its car adapter has a tubular power jack on one end and connects to a standard cigarette lighter jack on the other. I noticed that my Coleman portable fan had the same plug, but its power pack was 6 D cells for 9v. At the time I had just changed the battery on my HD Sportster, and the old battery was still in pretty good condition, so it looked like a good power source for both TV and fan but no way to plug it in. A trip to Wall Mart and I found the missing link... female cigarette plug one end and "battery charger clips" other end in the boating section. I had planned on adding a resistor to drop the voltage for the fan, but found it wasn't necessary. I routinely change out my car batteries about every 3 years, and keep the old ones for hurricane season. Thought I would pass this idea along.. regards Les