Dangling Alternator Question
loa1...@gmail.com
leaving it unconnected, and charging my battery at night. My question
is this: because the voltage rectifier is unconnected, the alternator
is now dangling (not outputting into anything). Is this harmful to
the alternator or just plain dangerous?
Mark Olson
It won't hurt anything or anyone so long as you keep the wires
from touching anything. Wrap some tape over the ends of any
unconnected wires until you replace the regulator.
What make, model, and year is your bike?
lne...@gmail.com
It's a '97 BMW F650. And yes, I made sure that alternator wires were
cared for. Thanks for your response.
Rob Kleinschmidt
I think you've got a permanent magnet alternator with
a regulator/rectifier combo. In that setup, the regulator/
rectifier has to dissipate unused current as heat rather
than de-energizing an electromagnetic rotor.
For a permanent magnet setup, I'm not sure about leaving
the R/R completely disconnected. electrexusa.com is a
good resource. I'd also recomend the beemershop in
Scott's Valley, Ca as a pretty good source of advice and
online parts.
Mark Olson
> For a permanent magnet setup, I'm not sure about leaving
> the R/R completely disconnected. electrexusa.com is a
> good resource. I'd also recomend the beemershop in
> Scott's Valley, Ca as a pretty good source of advice and
> online parts.
Not sure what would be hurt by leaving the stator disconnected
on a PM alternator. No power would be generated since no
current would be flowing in the windings.
Hans-Christian Becker
The only thing that I would worry a bit about is that the output
voltage will rise to _very_ high levels if there is no load. I
_think_ the insulation will withstand that, but YMMV, as always.
No-load voltages of well over 100 V would not surprise me.
Permanent magnet alternators as used in bikes are inherently
short-circuit proof---the current is self-limiting, and since
the short-circuit voltage over the windings is small the power
loss in the alternator windings is small.
--
Dr. Hans-Christian Becker
'96 VN750 SM5TLH KG6POK
Uppsala, Sweden
.
> It's a '97 BMW F650. �And yes, I made sure that alternator wires were
> cared for. �Thanks for your response.
Do NOT run your engine with a permanent magnet alternator disconnected
from the rectifier regulator, except to test the open circuit voltage.
The insulation on the alternator stator coils is just a thin layer of
plastic meant to withstand 20 or 30 volts and it can be punctured by
open circuit voltage of 90~100+ volts.
Mark Olson
> In article <dvadnS6FyvVn5ozU...@posted.visi>,
> Mark Olson <ols...@tiny.invalid> wrote:
>>Not sure what would be hurt by leaving the stator disconnected
>>on a PM alternator. No power would be generated since no
>>current would be flowing in the windings.
> The only thing that I would worry a bit about is that the output
> voltage will rise to _very_ high levels if there is no load. I
> _think_ the insulation will withstand that, but YMMV, as always.
>
> No-load voltages of well over 100 V would not surprise me.
I had considered that as a hazard, but most service manuals say to
expect 60 to 100VAC when testing open-circuit voltage of a PM alternator.
> Permanent magnet alternators as used in bikes are inherently
> short-circuit proof---the current is self-limiting, and since
> the short-circuit voltage over the windings is small the power
> loss in the alternator windings is small.
Correct.
In any case, I would probably ride the bike with the alternator disconnected
only as long as it took to get home, and I would immediately order and
install a replacement reg/rect unit.
Mark Olson
> On Nov 4, 4:10ï¿œpm, lneu...@gmail.com wrote:
>
>
>>It's a '97 BMW F650. ï¿œAnd yes, I made sure that alternator wires were
>>cared for. ï¿œThanks for your response.
>
>
> Do NOT run your engine with a permanent magnet alternator disconnected
> from the rectifier regulator, except to test the open circuit voltage.
>
> The insulation on the alternator stator coils is just a thin layer of
> plastic meant to withstand 20 or 30 volts and it can be punctured by
> open circuit voltage of 90~100+ volts.
So how come it's safe to test the stator open circuit voltage but
not leave it that way for a while? If the insulation is only
going to withstand 20 or 30 volts as you claim, isn't it going to
pretty much immediately break down at a typical 100VAC open circuit
voltage?
Not sure what bike alternators you've had experience of, but I understnad
they usually use clear insulated magnet wire rather than plastic,
the only stators I've seen with plastic coating it just a cover over the
magnet wire, not insulating the wire itself.
.
> So how come it's safe to test the stator open circuit voltage but
> not leave it that way for a while? �If the insulation is only
> going to withstand 20 or 30 volts as you claim, isn't it going to
> pretty much immediately break down at a typical 100VAC open circuit
> voltage?
It may take a while for the voltage to puncture the insulation, but,
given time, temperature and immersion in oil, the windings can short
to the metal core, taking one phase out of use and reducing output
power by half.
>
> Not sure what bike alternators you've had experience of, but I understnad
> they usually use clear insulated magnet wire rather than plastic,
> the only stators I've seen with plastic coating it just a cover over the
> magnet wire, not insulating the wire itself.
Look at all those Suzuki GS stators that went bad.
The plastic connectors that hook the stator and the rectifier
regulator to the main wiring harness would get hot and melt, and
that's almost the same as running the alternator open circuit.
Loa
So I just spoke to the tech support at electrosport.com, and he stated
that there would be no harm done leaving stator unconnected. Now, I
hear and believe what you are saying, so would a viable solution
(besides actually replacing the bad VR :) ) be connecting the stator
to the VR, but leave the VR output dangling?
Hans-Christian Becker
With the possible caveat that "almost" may be worse than "completely".
It is too long since I did three-phase power, but the imbalance caused
by only one or two phases being open circuit could possibly be worse
for the alternator than having all three disconnected.
Having said that, I would think that vibrations, high temperature, and
oil is what kills most stators.
.
> So I just spoke to the tech support at electrosport.com, and he stated
> that there would be no harm done leaving stator unconnected.
Oh, what do the tech support kids know, anyway?
> Now, I
> hear and believe what you are saying, so would a viable solution
> (besides actually replacing the bad VR :) ) be connecting the stator
> to the VR, but leave the VR output dangling?
I am assuming that your motorcycle has the typical permanent magnet
alternator, NOT a car type excited field alternator.
If you run an excited field alternator disconnected from a battery, or
from the regulator, nothing bad happens.
A permanent magnet alternator really needs to have a battery in good
condition connected to the regulator DC output.
The battery forces the system to operate somewhere near battery
voltage.
An almost dead battery forces the alternator to run at about 12.0
volts or less.
A fully charged battery in good condition lets the alternator run up
to around
18 volts before gassing and boiling the electrolyte, if the regulator
fails.
The regulating circuit tries to keep the voltage between about 14.5
and 15.5~16.0 volts, depending on whether it's a flooded-cell battery
or a maintenance free AGM battery.
The permanent magnet alternator system uses a three phase full wave
rectifier bridge to change the AC into DC. You will find a .pdf file
that shows a typical rectifier bridge at
http://www.electrosport.com/electrosport_electrical_home.htm when you
click on the technical links.
If you have an ohmmeter, you can easily do the diode check, but you
would need a variable voltage power supply to test the voltage
regulating circuitry in the regulator.
If one of the diodes is blown out, this reduces the power output of
the alternator by half, for half a cycle. Blow out two diodes and the
output could be anywhere from half power to almost nothing, depending
on which of the six diodes is blown.
In order to regulate voltage, this type of shunt regulator has a
silicon control rectifier (SCR) hooked up between one pair of power
diodes and there is a zener diode that senses when voltage rises above
about 14.5 ~ 15 volts *with the regulator conected to the battery*.
If you try to operate this system with the regulator output
disconnected from the battery, the zener diode will continously tell
the SCR to shunt excess current to ground and the regulator will get
very hot when the engine is running.
It's normal for an SCR or a diode to get *somewhat* hot when you run
power through it, though. That's why the regulator is housed in a
finned aluminum heat sink.
But the charging system of a modern motorcycle is really designed to
burn up excess power that isn't charging the battery by lighting the
headlight and taillights, not by continuously shunting ALL the power
to ground via the SCR.
The best solution would be to avoid riding the motorcycle until the
rectifier regulator is replaced.
.
wrote:
> With the possible caveat that "almost" may be worse than "completely".
> It is too long since I did three-phase power, but the imbalance caused
> by only one or two phases being open circuit could possibly be worse
> for the alternator than having all three disconnected.
I suppose you're speaking of some sort of electrical "imbalance", not
mechanical imbalance. The magnetic fields inside a permanent magnet
alternator just wouldn't be strong enough to move the windings.
In a three-phase wye-wound stator, the phase rotation is A > B > C,
with
power returning from C > A, etc., via the power diodes.
A blown diode just interrupts the orderly return of power to the
following phase.
The biggest 3-phase generator I ever worked on was one of the 250
megawatt units at Boulder Dam, on the Colorado River.
We secured the generator by isolating it from the circuit so it
couldn't run as a motor, and closed the butterfly valve in the
penstock and chained the wicket gates shut so water couldn't move the
turbine.
Then we crawled around inside the generator, looking for burned
windings and windings that had been dislocated by the powerful
magnetic fields inside the generator while operating.
The Older Gentleman
> Look at all those Suzuki GS stators that went bad.
Once again, you use your 'experience' of a particularly crappy design,
that's now 30 years old, and think it applies to modern kit.
You're full of shit.
--
BMW K1100LT Ducati 750SS Yamaha XT600E Honda CB400F & SH50
chateau dot murray at idnet dot com
"What you're proposing to do will involve a lot of time
and hassle for no tangible benefit."
.
Gentleman) wrote:
> You're full of shit.
Eat it.
.
> In order to regulate voltage, this type of shunt regulator has a
> silicon control rectifier (SCR) hooked up between one pair of power
> diodes and there is a zener diode that senses when voltage rises above
> about 14.5 ~ 15 volts *with the regulator conected to the battery*.
Curiousity led me to google up information on the BMW F650.
It seems that it has a remote sensing lead coming from the ignition
switch similar to a Honda.
The extra voltage drop across this long lead causes the voltage
regulator to
think that battery voltage is higher than it actually is.
So some technically minded owners figured a way to shorten the lead by
adding a relay...
richard cortese
"." <yefel...@yahoo.com> wrote in message
news:9df078e9-2eec-4b17...@u29g2000pro.googlegroups.com...
On Nov 5, 10:28?am, "." <yefelnag...@yahoo.com> wrote:
> In order to regulate voltage, this type of shunt regulator has a
> silicon control rectifier (SCR) hooked up between one pair of power
> diodes and there is a zener diode that senses when voltage rises above
> about 14.5 ~ 15 volts *with the regulator conected to the battery*.
Curiousity led me to google up information on the BMW F650.
It seems that it has a remote sensing lead coming from the ignition
switch similar to a Honda.
The extra voltage drop across this long lead causes the voltage
regulator to
think that battery voltage is higher than it actually is.
************
I think you mean the long lead causes the voltage regulator to think the
battery voltage is lower.
Rick
.
> "." <yefelnag...@yahoo.com> wrote in message
> The extra voltage drop across this long lead causes the voltage
> regulator to
> think that battery voltage is higher than it actually is.
> ************
> I think you mean the long lead causes the voltage regulator to think the
> battery voltage is lower.
Right. I was trying to post and cook pasta at the same time and got
distracted. (1)
The battery gets overcharged because the extra connectors and the
ignition switch contacts and about six feet of small gauge wire keep
the zener diode from triggering and the SCR doesn't shunt excess power
to ground.
The diodes also have to put up with excess voltage from continual
charging and they tend to blow out.
The F650 has a $250 OEM regulator...
(1) Write that down, Older Gasbag, so you don't forget all the things
I've said that displesed you.
Rob Kleinschmidt
> On Nov 5, 5:25 pm, "richard cortese" <ricor...@earthlink.net> wrote:
>
> > "." <yefelnag...@yahoo.com> wrote in message
> > The extra voltage drop across this long lead causes the voltage
> > regulator to
> > think that battery voltage is higher than it actually is.
> > ************
> > I think you mean the long lead causes the voltage regulator to think the
> > battery voltage is lower.
>
> Right. I was trying to post and cook pasta at the same time and got
> distracted. (1)
>
> The battery gets overcharged because the extra connectors and the
> ignition switch contacts and about six feet of small gauge wire keep
> the zener diode from triggering and the SCR doesn't shunt excess power
> to ground.
>
> The diodes also have to put up with excess voltage from continual
> charging and they tend to blow out.
>
> The F650 has a $250 OEM regulator...
All BMW parts come with those very special
BMW prices.
I took a quick look at my BMW parts CD and
besides the regulator, they show a separate
diode (part #s 61 312 346 432 and 61 312 346 465)
Not sure what's up with that. Nice if you could
really replace them separately. I guess the diode
may not be for the main charging current though.
.
> I took a quick look at my BMW parts CD and
> besides the regulator, they show a separate
> diode (part #s 61 312 346 432 and �61 312 346 465)
The protective diode is a logic diode that keeps current flowing in
the correct
direction. It's associated with a starter solenoid *enabling* relay,
the neutral
switch and the clutch lever switch.
http://faq.f650.com/FAQs/Photos/ElecPhotos/wiring1-1.gif
In this wiring diagram, green is hot when the ignition switch in in
the ON position
and orange is ground.
The voltage regulator gets its voltage information round-aboutly,
through the
ignition switch, like a Honda VFR...
Rob Kleinschmidt
Nice find.
.
> On Nov 6, 4:22�am, "." <yefelnag...@yahoo.com> wrote:
> > The protective diode is a logic diode that keeps current flowing in
> > the correct
> > direction. It's associated with a starter solenoid *enabling* relay,
> > the neutral
> > switch and the clutch lever switch.
> >http://faq.f650.com/FAQs/Photos/ElecPhotos/wiring1-1.gif
> Nice find.
Pssssst! Don't tell The Old Gasbag that I found the answer by googling
the web. He thinks that's a sign of weakness...
Ted Mittelstaedt
> The F650 has a $250 OEM regulator...
Nice save - a decent design these days should be using a fully electronic
regulator not a simple SCR jobbie, that would have full over and
undervoltage
protection. A DSP that does this is an off-the-shelf part that sells for
maybe
$1 OEM.
I'm amazed the aftermarket hasn't come up with a replacement for that
30-year-old discrete parts design from the Dinosaur age that you described
in your earlier post.
Ted
.
> Nice save - a decent design these days should be using a fully electronic
> regulator not a simple SCR jobbie, that would have full over and
> undervoltage protection. �A DSP that does this is an off-the-shelf part that
> sells for maybe $1 OEM.
Can you give us part numbers for an American made 3 phase full wave
rectifier bridge with a DSP chip in it? Most motorcycles would
probably be OK with a bridge that can handle about 400 watts. Only a
Gold Wingish land yacht garbage wagon would need more power.
>
> I'm amazed the aftermarket hasn't come up with a replacement for that
> 30-year-old discrete parts design from the Dinosaur age that you described
> in your earlier post.
The motorcycle aftermarket thrives on the ignorance of the owner, and
there are often international tariffs on foreign electrical/electronic
parts driving the prices up to about three times what a domestic
manufacturer would charge.
Rob Kleinschmidt
Not sure if you were talking about the $250 regulator for
the PM alternator or the complete energized rotor systems
from the earlier BMW boxers.
This place offers a well regarded PM alternator replacement
for the old energized boxer systems. This includes a thyristor
based regulator which I believe costs maybe $125 sold separately.
The whole system is based on one used in Ducs. I've heard
of problems on Ducs, but on elderly boxers it's well thought of.