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Old 01-12-22, 11:53 AM
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Road Fan
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Bikes: 1980 Masi, 1984 Mondonico, 1984 Trek 610, 1980 Woodrup Giro, 2005 Mondonico Futura Leggera ELOS, 1967 PX10E, 1971 Peugeot UO-8

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Originally Posted by gilesa View Post
Ass suggested above, there should be 6V of output with a 20 ohm resistor connected, or a little over 300mA short-circuit current. It is hard to get a good measurement while spinning by hand. One method I have used is to use the chuck of a variable-speed electric drill as a roller on the tyre. For comparison, I measured internal resistance at 6.5 ohms and inductance 86-108mH, varying with wheel position.
It's interesting to see your inductance measurement, and that it varies with position. This must be due to the magnetic circuits changing their reluctances as the stator and rotor pole pieces come into and out of alignment. I once designed a driver for an electronic for Ford, and the motor was based expressly on that principle of varying reluctance. Tough to control, but very efficient. I've measured motors in EE labs on special fixtures (not to mention an impedance bridge!), but I really can't attack hub or bottle dynos very well, just at home.
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