Cutout reading??

rivcokid

rivcokid

Senior Member
Good afternoon all - i'm wanting to confirm something since i'm no electric engineer. I was testing the cutout per the blue book. I tested output to case, and it say OL, which according to blue book is what you want. Then, i tested output to input, and it read about 120 on the ohm scale. The blue book says it should be infinite or open. Again, mine read 120, so is my cutout bad?

The reason for this is that my brand new battery (of a month ago) is reading .o6 volts!

Thanks
 
120 ohms will drain the battery. I = V/R. so with 6 volts and a resistance of 120 ohms the current to the generator, and then to ground, through the cutout would be 6/120 or 0.05 amps. Not a lot but enough to drain the battery over time.

Buy a battery maintainer with desulfator. The desulfator feature will have the best chance of restoring the battery. Disconnect the battery so that the cutout does not drain it again. Get a new electronic or rebuilt original cutout.
 
@nkaminar - thanks so much! It's been sitting for about 2 - 3 weeks while i had the carb rebuilt so that's enough time. Luckily i do have another cutout and will look into the maintainer. Thanks again!!!!
 
Imput to output should be infinte resistance - yours has an issue. The only place you should get a readung is from input to ground. Which is typically about 49 ohms.
 
The cut out relay is just an on/off switch that is turned on (switch closed) after the operating generator voltage reaches a point just above the battery voltage. The relay switch opens as soon as generator output voltage goes below battery voltage.

A lot of folks just use the modern power diode inside a cut out case that only allows current flow one way from generator to system. When the engine is shut down, the one way diode doesn't allow any back flow from the battery. These power diodes can fail to the open position where no flow can happen but they generally last a long time. Modern alternators use a bridge of similar diodes inside to do the same task.
 
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