I have posted this in another thread in the past, but it deserves being reiterated.
Disposable batteries off gas toxic chemicals including potassium hydroxide and hydrogen!
This happens through the chemical reaction that is continuous, and can not be prevented. It builds up pressure in the battery and many batteries explode or discharge toxic fluids toward the end of their life cycle.
I dive with a rebreather and we have gone through all of the data and understand the importance of not having power sources in the air we breathe. Additionally, I personally do not want those chemicals in an enclosed environment, like a wineador, to be able to permeate products that I will eventually set ablaze and consume.
I have never been one to preach what is right or wrong, rather I believe in sharing knowledge and letting you decide. With that said, I will never power a circulation source in my humidors with batteries.
I am sure you can go down to radio shack and ask them to put together a simple plug, resistor and connection to power a larger computer fan and run the wire out the back drain hole or across the seal of the door. Or better yet, if there is enough interest, I bet Ron at Avallo could whip up a simple kit that could have one or two fans and en external plug at minimal cost (but not sure on this last one).
Hope that helps,
TG