I have a small but important-to-me cactus collection that I will be overwintering in two small cold frames (roughly 25"x36" each).

These will be on an apartment balcony where there is no AC power.

I need to keep circulation going but I'm having trouble finding reliable battery operated fans that can survive the outdoors and are small enough to fit in a small cold frame.

I'd prefer solar over anything and I love the idea of these but the reviews are not good. I have thought about trying to hook up some PC fans to a 12v battery but I'm not sure if that would be adequate.

I'm open to any suggestions for battery powered fans!