Hello from UMass. I'm also here, although staff in Whitmore, not a student. I've been reading this board and playing around with stuff for a few months. Closest I've come to getting anything operational is a boxfan conversion with a 4 foot 3-blade prop I carved. Not sure I can get enough windspeed to get 12 volts out of it yet, but I finally got the motor conversion aspect working fairly well when I spin it with a drill.
There's tons of information on this discussion board, although there's no index so you have to search for things. Both the builtin search and the Google search have their advantages over the other. Searching for either treadmill or laptop will probably find plenty of previous posts related to what you're trying to do.
Laptops: if you're lucky enough to have one that you can get a 12 volt adapter for you'll have an easier time of it than otherwise. I've got Dells, and they don't sell a DC adapter for them. About the only option is to run an inverter to convert up to 117 volts, then use the Dell AC adapter, which is all fairly inefficient. People have talked about this on this board, and the general consensus seems to be that you need 20-70 watts, maybe more if you're charging the internal battery hard or watching videos on it. How many hours of the day you can run it on the power you accumulate in 24 hours from wind is a good question.
I suspect you'd need a good site, and if you're in town those will be hard to come by. Supposedly the ideal is something like 30 feet above anything that's within 300 feet, but I imagine lots of people live with less than that. If you're out on the fringes toward farm land maybe you could put something out in a field. Solar might make more sense, or maybe a combination.
I wouldn't mess with the charger circuitry in the UPS either. A simple linear voltage regulator good for a few amps and regulating to 13.8 volts or so should do the trick, and they're easy enough to build. If you had a blade over 4 ft you'd need to worry about overspeed on it, so you'd want furling and a dump load to use up surplus electricity. I think with 4 ft you can just let it run free when your batteries are charged, which a linear regulator will do.
The batteries may be free, but what's wrong with them? I've got one 800VA UPS that has a nice little 7.2 amp hour 12 volt battery and I liked the battery so much I bought 2 more like it. 7.2 amp hours * 12 volts = 86.4 watt hours, but you shouldn't pull most batteries down below 80% of full charge, so that would be about 69 watt hours. If your laptop, plus inverter losses, only takes 35 watts or so you could run for 2 hours. That's for new batteries that still have rated capacity. As long as you can hook up a bunch of them it should work. At BJ's in Greenfield you can buy a 72 amp hour deep cycle (still not the perfect battery) for $50.
Time to go drive home in this storm. Hope it's one of the last for this year. I'll get back online Sunday morning briefly.
Alan
