Further to may last post (this should go in Low buck projects. In fact I wil post it there):
Last evening I was fiddling with my two solar vents, figuring out just what parts were going to be needed to repair them. I found that one solar cell was pretty well pooched, and one motor was quite noisy. I figured I could likely pick up these items at the big (and fun) electronics surplus shop. But I thought, maybe I can find what I need on eBay, save a trip and have them mailed.
I searched "round solar cell" and found this:
what I already have! Looking more closely, some previous owner had bought these inexpensive solar exhaust fans, painted them white, and installed them under a presumably already existing chrome trim ring. Now, this is me cheaping out a bit, not replacing them with some $150 "marine" unit, but the last set would have lasted at least 7 years for the previous owner. For $80 the pair shipped, I figure I am well ahead, even if they only last another 7 years.
I think I will take them apart and try to install a rechargeable lithium battery of some kind, I have to figure out the optimal voltage of these units. is there a trick I need to know, some circuitry involved in putting in a battery?