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Discussion Starter #1 (Edited)
1987 Yamaha virago 535.
It would slowly drain the battery when running, and never charge more than 12,6V at high rpm's.

1: Measured the stator AC output with engine running, outputs gave 30V, 30V and 2,5V at 2000rpm. --> replaced the stator.
Note: also bought a new regulator, but did not install it because i didn't think the old one was broken.

2: Started the engine (new stator, same regulator) and measured the battery voltage to 13,5V ++ = the charging works fine.

3: Installed the new regulator and started the engine, it would not charge more than 11,5V at high rpm's.

4: Changed to the old regulator, it would now only charge to 12,6V at high rpm's, just like before.

5: Measured the new stator AC output to 30V on all three cables, so the stator seems so work fine!

Does anyone have hints or tips as to why the charging went faulty again, perhaps a ground or creeping current? All of this was done withing 10 minutes.

Note: both regulators show standard (OK) values when tested with multimeter, no value differences. All fuses are also OK. I will mension i have scoured youtube and google for similar cases, but can't seem to find any.
 

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Gone.
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I don't know that bike so without a manual I can only take a broad guess, but it sounds like possible your regulator connection isn't good. Also, some regulators ground through the base of the unit itself, so maybe make sure you're getting a good ground to the frame?
 

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Discussion Starter #3
I don't know that bike so without a manual I can only take a broad guess, but it sounds like possible your regulator connection isn't good. Also, some regulators ground through the base of the unit itself, so maybe make sure you're getting a good ground to the frame?
You were right, a bad ground caused the low charging voltage! :) cheers!
 

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Retired twice: Navy and as a govt contractor
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12,785 Posts
Good call Eye.
 

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Thanks. It's almost impossible to diagnose electrical issues over the Internet, but every once in awhile I stumble over a right answer.
Having seen similar failures doesn't hurt either. And a wrench as yourself certainly has a better shot at internet suggestions than most. That's still a good first shot suggestion though. Could have been several others.:thumbsup:
 
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