We tried the inexpensive fans from ebay, but after two failed in six months, it was back to square one. The battery fans didnt move the air enough to even notice, so we threw ours out after 2 months.
A friend of ours who fulltime's with us showed us his
fridge-fix, and he swore by it. We were tire of defrosting, so we ordered one as a last ditch effort.
We have not defrosted, not even once since installing more than 6 months ago! We even got rid of the cooler we used to carry to keep the food in.
We like to spread the word when we find something that makes living in an RV easier, and this definitely meets that criteria.