> I would vote
> for the fan with the d-cell battery. Much easier install. doesn't drain
> the aux. battery. The d-cell lasts all weekend, on 24-7.

The FridgeCool Fan (say, from Camping World) uses 2 D cells.
Mine has run about three weeks total without running down the
batteries.

http://tinyurl.com/ojhmd

I was cynically skeptical of the idea for several years, but
got one last spring and am a believer now....

                                Richard A Jones
                                Boulder, Colorado