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Toby Erkson wrote: > > Okay you techies, here's one for ya'll... > > I some solid answers (i.e. no guesses, please) on the rpm ratio between the > generator and the crank. I also would like to know at what rpm does the > generator begin to produce current. I believe at an idle the stock > generator isn't rotating fast enough to charge the system -- is this true? > > I talked to a custom alternator/starter shop and the owner was very helpful > in educating me on the differences between the alternator and generator, > beyond the obvious. I didn't know that if a generator isn't rotating fast > enough that it will stop producing current and it could even turn into a > motor, thus *using* current from the battery instead of charging it (so > keep that idle up)! > > Another item that would be helpful, since I have a mechanical engineer that > I work with, is the diameter of the crank pulley and the generator pulley. > She could help with the ratio if no one knows it. > > Thanks volks, > Toby Erkson > air_cooled_nut@pobox.com > '72 VW Squareback 1.6L modified to 2.0L > '75 Porsche 914 stock 1.8L According to my VW of America official service manual for 1968-73 Type 3, the voltage regulator/generator combination will cut in between 600 and 850 engine rpm. The 12 volt generator has a 2.3 ratio, so 850 rpm is 1950 on the generator. Below 850 rpm, your regulator/generator combination should cut out (no voltage) unless the points in the regulator are sticking. Nominal 14 volt output is engineered for 2000 rpm at the generator. Tim Dapper