Thread: Gen charging Q
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Old 03-30-2020, 12:39 PM   #7
rotorwrench
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Join Date: Jun 2010
Location: San Antonio, Texas
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Default Re: Gen charging Q

The old original type cut out switch has the can spot welded to the base in a couple of spots that can be seen if you pull it off the generator and turn it upside down. A person can carefully grind away the spot welds and take the cover off to see what's in there. Sometimes they just need the points cleaned.

The cut out switch senses a current/voltage generated after the engine is fired up. The generator pole shoes are magnetized by polarization procedure and the residual magnetism is enough to generate enough current to close that cut out switch and bring the generator on line. The battery is what sets the system voltage in a 3-brush generator system so it's very important to have good connections and correct polarity with the battery prior to starting the engine.

The modern replacements are just a relatively high amperage rated diode that only lets current go one way so the generator won't motor when you shut the engine down. The Fun Projects unit that folks talk about has a diode but it also has a current controller so that the unit will only put out current when it's needed for battery recharge or operation of the headlamps. The charge rate will drop down to little or nothing when the battery is completely recharged during running with no lights on. A normal three brush generator set up generates at a current rate that the brush is adjusted to all the time whether it needs it or not. The Fun Projects unit allows it to take a rest break when fully charged. It's a very simple form of regulator but they can easily be damaged by trying to jump start or connecting them the wrong way.

Last edited by rotorwrench; 03-30-2020 at 12:45 PM.
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