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1981 XV750 Virago Charging Problem.
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I have a 1981 XV750 Virago that does not seem to be
charging the battery correctly. I see about 12.5VDC
with the engine off, and about 13VDC when running; the
13VDC is not stable, and can dip below 12.8VDC or go up
to around 13.25VDC (varies with RPM). I have checked the
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The old Electrex USA website has a new URL, so you might want to web-search
for it and go there for information if you don't have a manual.
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Unfortunately the fault finding chart is still AWOL. I emailed
Electrosport's customer support person two weeks ago on 03/21, and
he said I wasn't the only person who has complained about it. He
promised to get the web folks to fix it but it's still broken.
I suggest that anyone who has downloaded the Electrosport fault
finding PDF file but couldn't open it, to send an email to:
info AT electrsport DOT com
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You cannot do the charging circuit test on a permanent magnet
alternator with shunt type regulator unless the battery is fully
charged..
The alternator might generate 300 watts at 5000 or 6000 RPM, but at the
lower RPM (around 3000 RPM) where charging circuit tests are done, the
alternator voltage might be dragged down too far by charging a low
battery.
It would expect to see the voltage rise up to 14.5 to 15.0 volts (check
your manual for exact voltage) and, the voltage should fall off sharply
when the voltage reaches the specified figure.
Don't forget that your voltmeter might no be reading right, it might
need calibration. I wish I could tell you what you could use for a
voltage standard, other than a calibrated power supply at an instrument
calibrating lab.
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resistance of the stator windings, and all three loops
measure about 0.6ohms. According to docs, the readings
should have been between 3 and 6 ohms each. When I run
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Low resistance readings would tend to indiate that the alternator
windings were shorted together. The insulation is just enamel, it will
break down under heat. Does the stator smell burned?
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the engine with the stator unplugged from the Vreg, the
three loops all measure equally and around 55VAC at 2500RPM;
this seems good, so I don't think the stator is the problem,
but please correct me if I'm wrong. I checked the internal
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What are you measuring, phase to phase to phase, or phase to ground?
There should not be any phase to ground reading with a wye-wound
alternator stator. They
have a neutral that ties all phases together and isn't grounded.
If you could get to the neutral while the engine was running and
getting the voltage reading of any phase to neutral, then the phase to
phase voltage would be 1.73 times phase to neutral.
I would expect more than 55 volts phase to phase. I would expect 70 to
90 volts phase to phase, but, again, check your manual for exact
information.
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diodes of the Vreg, and all checked out. I have a brand new
battery, so I know the battery is good. I'm thinking
the Vreg is the problem; anybody have any ideas as to
what may be the problem? Thanks for any help.
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What you describe doesn't sound so terrible on a bike with a
couple hundred watts of charging system. Depends on the
RPM. How does the voltage look with the headlight and tailight
disconnected ? How does it look at different RPMs ?
As I've mentioned in the past, Radio Shack has a 6 LED
"battery/alternator tester" which shows voltage in half volt
increments and is easy to mount on the handlebars. Gives
you a pretty good picture of how your charging system's doing
at different speeds with different stuff turned on and off.
If I thought it wasn't charging properly, I'd start by checking the
dumbass stuff like cables and connectors and take an inventory
of the total wattage of what I was trying to run. I wouldn't touch
the regulator, stator or anything else until I'd done this.
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Another possible is high resistance connectionsin the plastic
connectors. That will burn up a lot of power.
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Best Regards,
John Hermann
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The stators are not supposed to conduct to ground, either.
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