| You could do it, but car alternators need to spin much too fast to be direct-driven by a windmill. You'll need pulleys and gears to get the rpms up above 1000, whereas a homebuilt PM alternator can cut in at only 110 rpm and rarely exceeds 500 rpm (ideally). There are major friction losses involved in gearing the machine up, and these losses come right off the top and seriously hurt your low-wind performance. It's possible to rewind a car alternator with thinner wire to improve low cut-in speed, but the other problems still remain and it's complicated to do. The electromagnetic field in a car alternator also uses up power. There are also brushes that wear out, and the bearings are not designed for thrust loads. These facts all make a good case for building your own permanent magnet (PM) alternator instead of adapting a car alternator.
We have more details about selecting an alternator or generator for a wind turbine on our site here:
http://www.otherpower.com/otherpower_wind_alternators.html
Some discussion on this board about using car alternators for wind power and the relationship inside them between coil wire size, voltage and amperage:
http://www.fieldlines.com/story/2003/8/4/22368/12185
(Blatent Otherpower.com Self-Promotion)
A good and cheap (US$3) booklet 'Alternator Secrets' explaining exactly how car alternators work:
http://www.wondermagnets.com/cgi-bin/edatcat/WMSstore.pl?user_action=detail&catalogno=1101 |
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