It looks like the stator on my '01 SV650S is grounded. Can't find anything obviously wrong with the regulator rectifier, but I'm suspicious of it.
The battery (Shorai LiFePO) is recuperating on the charger and seems Ok.

Does anybody have recent experience (good or bad) with aftermarket parts
in this application? At one time there was some notion that MOSFET R/R
units were better than ordinary bipolar devices, but they aren't very
prominent in the Web searches done so far. Can't tell if they're too
common to be worth explicit mention, or not worth bothering with.

The bike has only about 28K miles on it, so I'm not exactly thrilled
with the OEM parts but my last experience in about 2002 with Electrex,
now Electrosport, made OEM look rather good.

Thanks for reading, any thoughts/stories appreciated!

bob prohaska

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bob prohaska <bp@www.zefox.net> wrote:

It looks like the stator on my '01 SV650S is grounded. Can't find anything obviously wrong with the regulator rectifier, but I'm suspicious of it.
The battery (Shorai LiFePO) is recuperating on the charger and seems Ok.

Does anybody have recent experience (good or bad) with aftermarket parts
in this application? At one time there was some notion that MOSFET R/R
units were better than ordinary bipolar devices, but they aren't very prominent in the Web searches done so far. Can't tell if they're too
common to be worth explicit mention, or not worth bothering with.

The bike has only about 28K miles on it, so I'm not exactly thrilled
with the OEM parts but my last experience in about 2002 with Electrex,
now Electrosport, made OEM look rather good.

Thanks for reading, any thoughts/stories appreciated!

bob prohaska

As a former '01 SV650S owner... let me just say I wish I still
had mine.

I never had to replace the stator in it. I sold the bike in 2008
with 40k miles on it, with the original Yuasa battery still working
fine. That after having completely drained it to zero volts by
leaving the aftermarket hand grip heaters on while at parked all
day at work, at least 4 times (!). I told the new owner all this,
with the understanding I was not claiming it had a fresh battery but
also wasn't charging him for one.

I would buy an OEM stator without hesitation. MOSFET regulators
should produce less heat in the stator, but I admit to not being 100%
convinced that they are better, if the stator is designed to handle
the short-circuit current when the shunt switching element fires in
the OEM regulator.

Another alternative to an aftermarket part like Rick's or Electrosport
would be to have someone rewind the OEM stator. People with such
skills seem to be thin on the ground near me or I just don't know
where to look. A friend of mine tried to rewind his Vmax stator
himself with mixed success.

Good luck!

--
FJR1300A, GL1000, KLR650A6F, EX250J9A, Vespa Ciao

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Mark Olson <olsonm@tiny.invalid> wrote:

As a former '01 SV650S owner... let me just say I wish I still
had mine.

I agree, it's a very good machine. As I get older the lighter
weight than my VFR800 makes the SV somewhat preferrable. Until
now the SV beat the VFR all hollow for electrical reliability.
Now it's a tie 8-(

I never had to replace the stator in it. I sold the bike in 2008
with 40k miles on it, with the original Yuasa battery still working
fine. That after having completely drained it to zero volts by
leaving the aftermarket hand grip heaters on while at parked all
day at work, at least 4 times (!). I told the new owner all this,
with the understanding I was not claiming it had a fresh battery but
also wasn't charging him for one.

That's a surprising story. My SV has gone through its share of
batteries, but they usually lasted a couple years, which I thought
not outrageously bad. I don't think it ever failed to start and
only once had measurable charging problems. Cleaned up with wiring
and put a fan on the RR. It worked for four years and 3000 miles.
I thought I was home free....Now a grounded stator.

I would buy an OEM stator without hesitation. MOSFET regulators
should produce less heat in the stator, but I admit to not being 100% convinced that they are better, if the stator is designed to handle
the short-circuit current when the shunt switching element fires in
the OEM regulator.

Far as I can see the only way to fry a stator is to have the battery
discharge through a leaky rectifier diode into the winding. With only
the DC resistance of the wiring to limit current, that might be enough
to cook a winding. Semiconductor diodes can recover if they cool fast,
which seems to be what happened here (and on my VFR).

I note with interest that the main fuse is 20 amp per the manual. It
looks like I increased it to 30 to avoid blowing the fuse with cornering
lights and HotGrips. So long as the rectifier didn't fail, I got away
with it. Thanks for prompting me to think this through carefully!

Another alternative to an aftermarket part like Rick's or Electrosport
would be to have someone rewind the OEM stator. People with such
skills seem to be thin on the ground near me or I just don't know
where to look. A friend of mine tried to rewind his Vmax stator
himself with mixed success.

I don't think the economics make sense so long as OEM replacements are available. A new stator is ~$300, that's three hours of shop time. It
dosen't seem plausible that somebody can do a better-than-factory rewind
in three hours. Give them five or six and you'd get a superior product, but
now we're talking artisanal work.

Good luck!

Thank you!

bob prohaska

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bob prohaska <bp@www.zefox.net> wrote:

Far as I can see the only way to fry a stator is to have the battery discharge through a leaky rectifier diode into the winding. With only
the DC resistance of the wiring to limit current, that might be enough
to cook a winding. Semiconductor diodes can recover if they cool fast,
which seems to be what happened here (and on my VFR).

To my complete surprise, the stator looked perfectly fine. No sign
of overheating, no physical damage visible. Still, the winding
is solidly shorted to the core. I wiggled the wires and pressed on
the windings to see if a test light could be made to flicker, but
no luck.

The core looks carefully insulated, with what appears to be green
plastic molded over all the surfaces in possible contact with wires.
The splices are all sheathed in fabric sleeves, the output wires
carefully strain-relieved with more insulating sleeves. I'm really
baffled how the wires manage to get near the core, to say nothing of
making electrical contact to it. A varnish failure could lead to a
turn-to-turn short, but a turn-to-core short is very hard to explain.

For now I've ordered an OEM replacement (>$300!) and will install
that.

Thanks for reading and any ideas!

bob prohaska

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bob prohaska <bp@www.zefox.net> wrote:

For now I've ordered an OEM replacement (>$300!) and will install
that.

Thanks for reading and any ideas!

I'd very carefully buzz it out before installing it...

--
FJR1300A, GL1000, KLR650A6F, EX250J9A, Vespa Ciao

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bob prohaska <bp@www.zefox.net> wrote:

Mark Olson <olsonm@tiny.invalid> wrote:

bob prohaska <bp@www.zefox.net> wrote:

For now I've ordered an OEM replacement (>$300!) and will install
that.

Thanks for reading and any ideas!

I'd very carefully buzz it out before installing it...

I'm pondering taking an ohmmeter to the shop for a test before
accepting it. Probably more symbolic than practical, though.

I'd say the odds miniscule that there will be any issues with the
new stator, but if there are, they are better found at the shop than
at home.

I have no doubt that the manufacturer does check for shorts to earth
and also tests the winding resistance, they may even have a test
setup that spins a rotor over the stator and measures its output
under load. They probably don't do a hi-pot test, but who knows?

--
FJR1300A, GL1000, KLR650A6F, EX250J9A, Vespa Ciao

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Mark Olson <olsonm@tiny.invalid> wrote:

bob prohaska <bp@www.zefox.net> wrote:

For now I've ordered an OEM replacement (>$300!) and will install
that.

Thanks for reading and any ideas!

I'd very carefully buzz it out before installing it...

I'm pondering taking an ohmmeter to the shop for a test before
accepting it. Probably more symbolic than practical, though.

bob prohaska

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Mark Olson <olsonm@tiny.invalid> wrote:

I'd say the odds miniscule that there will be any issues with the
new stator, but if there are, they are better found at the shop than
at home.

Agreed.

I have no doubt that the manufacturer does check for shorts to earth
and also tests the winding resistance, they may even have a test
setup that spins a rotor over the stator and measures its output
under load. They probably don't do a hi-pot test, but who knows?

A HiPot test could double as a short to earth test if the voltage
is limited to a couple kV. I can't imagine it would provide a good
prediction of service life, though it'd be better than nothing.

It does seem that internal stator faults aren't unknown in the electric
power industy. Here's an article on the subject:

https://cdn.selinc.com/assets/Literature/Publications/Technical%20Papers/6718_UnderstandingGenerator_DF_20160204_Web4.pdf?v=20191010-214826

I don't claim to understand it well at all, but the message seems to be
that stator failures are common enough in grid-scale alternators to be
worth monitoring for. The method seems to be finding a neutral point in
the stator winding and watching for it to deviate too much from neutral.

Once the SV650S is fixed I'll try dissecting the old stator to see if the failure can be found. First step will be to find the neutral point of the
wye, split it, and check each winding. Beyond that I can't think of any non-destructive explorations. If you have any ideas please share them!

Thanks for reading,

bob prohaska
.

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bob prohaska <bp@www.zefox.net> wrote:

Once the SV650S is fixed I'll try dissecting the old stator to see if the failure can be found. First step will be to find the neutral point of the wye, split it, and check each winding. Beyond that I can't think of any non-destructive explorations. If you have any ideas please share them!

My brain hurts after trying to read that paper... I'm plumb out of
ideas but if you find anything interesting about your SV650S stator
failure (even if only mildly) by all means please report back.

--
FJR1300A, GL1000, KLR650A6F, EX250J9A, Vespa Ciao

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Mark Olson <olsonm@tiny.invalid> wrote:

My brain hurts after trying to read that paper... I'm plumb out of

I felt a little woozy myself...

ideas but if you find anything interesting about your SV650S stator
failure (even if only mildly) by all means please report back.

Will do. Picked up the new stator today, ohmed it out on the counter.
The surface finish of the core material is different, looks like it
has some sort of coating not present on the original.

bob prohaska

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Mark Olson <olsonm@tiny.invalid> wrote:

ideas but if you find anything interesting about your SV650S stator
failure (even if only mildly) by all means please report back.

With the new stator installed the SV seems to charge quite well,
13.7 volts on a LiFePO4 battery 3 days after a 30 mile ride.

My attempt to isolate the short in the old stator succeeded after
a fashion. Gently sawing through the common point of the wye winding
left one phase connected to the core, the other two still connected
to each other but not to the core.

Unwinding the shorted turns from the output end with a test light
hooked up got me all the way back to the center of the wye. About
five turns out there was a blackened spot on the green plastic over
the core. A test probe revealed bare metal amid the charring.

The mechanical integrity of the windings was impressive. Attempts to
pry the splice free of the varnish, rather than cut it, were totally
futile. It seems quite implausible that vibration played any role in
the failure. The wires simply can't move. There may have been an air
bubble at the point of failure, allowing a track to form, but the low
voltage makes that hard to understand. Most insulating enamel will
hold off a couple hundred volts (if it's undamaged). Probably the
enamel got scratched and there was a flaw in the green plastic over
the core. Any air gap must have been extremely small, less than a
few thousandths of an inch, to permit a track to form.

The plastic sleeving over the output wires was brittle and cracked
during disassembly. It had nothing to do with the failure, but did
suggest age has taken a toll on the materials of construction.

Around a year ago I notied a fast blink on the turn signals when the
revs went over about 7k. It only happened on vigorous engine braking
toward the end of my exercise ride route. I checked the voltage with
a simple LED bargraph voltmeter and saw no anomaly when the flasher
was hyperventilating, but I couldn't reproduce the effect in the shop
when a good voltmeter was handy. I chalked it up to an old flasher.
Perhaps it was the stator putting hash on the harness.

For a while I harbored notions of trying to rewind the core as a spare.
Seeing how well it was made and how hard it was to take apart that seems unrealistic. I'll save it as a relic and curiosity, and devoutly hope I
never have a reason to attempt a rewind.

Thanks for reading,

bob prohaska

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bob prohaska <bp@www.zefox.net> wrote:

Around a year ago I notied a fast blink on the turn signals when the
revs went over about 7k. It only happened on vigorous engine braking
toward the end of my exercise ride route. I checked the voltage with
a simple LED bargraph voltmeter and saw no anomaly when the flasher
was hyperventilating, but I couldn't reproduce the effect in the shop
when a good voltmeter was handy. I chalked it up to an old flasher.
Perhaps it was the stator putting hash on the harness.

Looks like the fast flash had nothing to do with the stator. On a short
(18 mile) freeway jaunt the fast turn signal came back, at relatively
low revs. That really spooked me, thinking the new stator was at fault.

However, the fast cadence continued down to key-off, and it was possible
to observe that the right rear turn signal bulb was not working. Exactly
as designed. Checked the bulb, it's ok. Hopefully re-seating the bulb in
the socket fixed it. If not, at least it won't strand me.

Thanks for reading!

bob prohaska

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