Is it possible to test stator without draining oil or removing sidecover?

[LilBeaver]

Does anyone know if it is possible to test the stator without removing the sidecover or draining the oil?

 

I know that one can test it by starting the bike and checking the voltage at the battery, but what I do not know is if this is a conclusive test for determining whether the stator is functioning properly.

 

Thanks in advance.

Edited August 25, 2009 by LilBeaver
clarification

[LilBeaver]

Sorry folks, I just found a post that describes a way to get to the wires to do the resistance test. I don't know how I missed that in the original searching.

 

Maybe it would be worthwhile for this thread to get deleted since it is certainly not necessary.

[MiCarl]

Voltage test at the battery shows the condition of the entire charging system. If battery voltage is good then the discrete components are good. Only if the voltage at battery is wrong do you need to check the other components.

 

Referring to your other post: A bad stator will not damage the radio or any other components on the motorcycle. A bad regulator/rectifier letting the voltage go high can damage any number of things. Fortunately, regulator/rectifiers seem to generally fail to a low voltage condition.

[LilBeaver]

Thanks Carl, I replaced the regulator a few weeks ago due to it failing. It was putting around 17V to the battery (which basically blew the battery up, killed ALL of my lights and at the time, I thought that was it). Just recently I had issues with the radio.

I read in a really old post about someone that had similar radio issues, had the radio replaced, issues repeated, radio replaced the 2nd time along with the stator. His dealer said that part of the stator had melted causing a higher voltage to be put out which somehow managed to fry the radio. -- While I'll admit this sounds a wee bit fishy, I had figured that it was possible that if something caused a spike in the electrical system that could have caused my regulator/rectifier to fail thereby shocking the rest of the system... Still being odd that 5,000 miles later (with the radio being used basically all the time) the radio would just now start showing funny behavior.

 

Thanks again,

Rick M.

Edited August 25, 2009 by LilBeaver

[RandyR]

I will tell you that if solid state electronics take a voltage spike, it may be a while before they completely fail.

 

Experience learned in large computer rooms. Very hard to track problems like that.

[LilBeaver]

I will tell you that if solid state electronics take a voltage spike, it may be a while before they completely fail.

 

Experience learned in large computer rooms. Very hard to track problems like that.

 

Good to know. I am definitely leaning towards this as a left-over problem from the 17 volts that was going through the system for who knows how long before I had the breakdown a few weeks ago... Also, it seems that everything else that I can manage to test seems to be coming up okay...

 

Thanks again!

[MiCarl]

His dealer said that part of the stator had melted causing a higher voltage to be put out ....

 

That's a lot like saying "a spark plug failed causing the engine to produce more horsepower".

 

You can visualize electricity just like water flowing in a pipe.

 

Your stator is the pump. The amount of voltage (pressure) it puts out is only effected by rpm (how fast you run the pump). Anything that malfunctions in the stator (pump) reduces the output.

 

If you don't have enough load (open valves) in the piping the voltage (pressure) will get too high and things start to break.

 

To keep the pressure from going too high there is a relief valve (voltage regulator) that bleeds off any excess so stuff doesn't go boom.

 

That's why we don't cook regulator/rectifiers and stators by loading up with accessories. The stator always works at maximum capacity anyhow, and any electricity we use doesn't need to be bled off by the regulator/rectifier - reducing it's work load.

 

What does happen when we put on too much accessory load there isn't enough water (electricity) left to refill the bucket (battery) and we end up sitting in the dark.

[LilBeaver]

I do understand what you have explained and I realize what the regulators are supposed to do.

I also realize that you know far more about this stuff than I do, so by me continuing this here, I am not challenging your experience or expertise, I am simply trying to further my understanding by proposing that there may be a little more to this.

 

I also realize the premise here may seem pretty far fetched (this being based on what the dealer had said), but before it gets dismissed here is a thought:

 

Generator/alternators/stators work of the principle of electromagnetic induction (Faraday's law). That is a time varying magnetic field produces an electric field in a conductor. In the case of a stator, the conductor is coils of wire. That is a current is induced in the coils of wire (that make up the stator) at which point the current is 'channeled' off of the coils, through the rectifier (where it is converted to DC) and the regulator where the 'excess' is shunted and then into the rest of the bike.

 

Basic Ohm's law law tells us that V=IR (Voltage = current * Resistance). The coils (on a 2nd Gen) have an internal resistance of somewhere between 0.28 and 0.34 ohms. And the induced electric fields [current] is what is driven - giving rise to the electrical potential energy (ie. the voltage). If there is a sudden increase in the resistance there will be an increase in voltage that ought be taken care of by the regulator/rectifier.

So, if something happened inside the stator, such as two parts of the coil melting together, which could cause an increased resistance this would cause an increased voltage that would then be taken care of by a properly functioning regulator/rectifier. If the rectifier is being overloaded by an improperly functioning stator then it would breakdown and seize to do what it is supposed to do thereby delivering a higher voltage through the system.

 

BUT, before the breakdown of the regulator/rectifier, if there is just slightly more power going through the regulator/rectifier than is supposed to, it may be able to handle it for some period of time but may eventually breakdown due to this being 'overloaded'. So in this case, in between being functional and non-functional the charging system, while being tested solely based on the voltage at the battery (or any other power point on the bike) it would indicate that at that time the charging system is fine, but it would be misleading as the rectifier unit is being overworked and will fail sooner than it would if it was not overloaded.

What I wanted to be sure of was that the stator was functioning as it is supposed to as to not overload the rectifier/regulator and have that go out again. I realize that parts just fail sometimes; albeit from heat, vibration, corrosion, or just 'natural causes'. I just wanted to be sure that there was not something else going on that I was not seeing.

 

I realize that typically stator problems are simply that they stop producing the power that they are supposed to be producing. Since the fellow member told me that his dealer said that the stator was producing more than it should, I was giving him the benefit of the doubt here and trying to come up with a way that it may have happend as well as a way to verify that mine is not doing that. I KNOW this is a big stretch, and sometimes knowing a lot about physics and a little about these specific bike parts is a big disadvantage for me... Especially when I get flustered working on my own bike, :- \

 

Sorry this was so wordy, but that is my thought process here which is not the most probable way for these things to fail, but that was the only way that I could see justification of a voltage spike coming from the stator.

 

When my regulator went out, I heard a gd awful noise out of the speakers and through the audio system while ALL of my lights (that were on) blew out, so when the radio worked fine after I got everything back together I was suprised - so this could be related to that.

Edited August 26, 2009 by LilBeaver
Added a few commas

[MiCarl]

 

Basic Ohm's law law tells us that V=IR (Voltage = current * Resistance). ..... If there is a sudden increase in the resistance there will be an increase in voltage that ought be taken care of by the regulator/rectifier.

So, if something happened inside the stator, such as two parts of the coil melting together, which could cause an increased resistance this would cause an increased voltage that would then be taken care of by a properly functioning regulator/rectifier. If the rectifier is being overloaded by an improperly functioning stator then it would breakdown and seize to do what it is supposed to do thereby delivering a higher voltage through the system.

 

 

Couple of flaws in your reasoning. 1- when the coil melts together resistance goes down (instead of a long wire in loops it becomes a short tube) and 2 in your solution of V=IR you assumed current is constant, why not assume voltage is constant and current goes down as resistance goes up?

 

But in your question you have caught me on something I was afraid I'd be caught on when I oversimplified: The output of an alternator isn't really measured in volts (just like pressure doesn't give you the whole story on pumps).

 

We talk about volts and amps when referring to electrical systems but what really matters is power. Power can't be measured directly (it's calculated from volts and amps) and because certain elements of the system are fixed we can cheat and use volts or amps for most of our diagnostics.

 

On the plumbing example I only talked about the pressure the pump created and glossed right over volume. The true measure of the pump is actually the pressure * output volume. In an electrical system the volume is measured in amps. The true measure of the alternator is Power=Volts*Amps and the unit is watts.

 

So, using that algebra they forced on us in the old days: P=V*I and V=I*R so P=(I*R)*I which means P=I*I*R, Power = Current squared times Resistance.

 

Power is fixed by the engine speed. So, when resistance goes up current goes down and vice versa.

 

Now, doing some more math (V=IR ~ I=V/R) Substituting in above P=(V/R)*(V/R)*R ~ P=V*V/R. Again power is fixed so as resistance goes up voltage also goes up. When you turn on goodies the resistance of the system goes down and the voltage drops. The regulator is like an automatic goody, if there aren't enough other goodies on to use the power output by the alternator it turns itself on to use some of the power and keep the voltage in check.

 

So, hopefully I've proven that what is in question about the alternator is it's power output. What determines that?

 

The power the alternator can output is determined by the strength of the magnet, the rpm of the engine and the length of wire in the coils. (I am deliberately neglecting loss due to resistance in the coils, which is minor). Increase any of the three (magnet, rpm, wire length) and the power output goes up. Decrease any of them and the power output goes down.

 

Shorting the coil effectively makes the coil less long (shorter!) reducing the power output of the alternator. Yes, resistance in the coil goes down (that's why we use an ohm meter to see if they've shorted) but that is more than offset by the reduction of the effective length.

Edited August 26, 2009 by MiCarl

[LilBeaver]

Couple of flaws in your reasoning. 1- when the coil melts together resistance goes down (instead of a long wire in loops it becomes a short tube)

I was simply playing the 'what if' the resistance went up since I did not know exactly what happens when one of these puppies fail. This makes sense though, overheating or whatever would melt these things together. Okay.

 

and 2 in your solution of V=IR you assumed current is constant, why not assume voltage is constant and current goes down as resistance goes up?

...

But in your question you have caught me on something I was afraid I'd be caught on when I oversimplified: The output of an alternator isn't really measured in volts (just like pressure doesn't give you the whole story on pumps).

My assumption that the current was constant was based on the way that the power, in the end, is produced. That is the induction due to the time varying magnetic field inside the wires. At this point, knowing that when one of these things fails it melts the coils together or whatever makes this assumption a moot point, so I think I will forgo the winded explanation of my assumption here.

 

 

Shorting the coil effectively makes the coil less long (shorter!) [oops ] reducing the power output of the alternator. Yes, resistance in the coil goes down (that's why we use an ohm meter to see if they've shorted) but that is more than offset by the reduction of the effective length.

 

Understood.

 

The basis of my initial thought was that if somehow there was to be an increase in resistance which I am pretty sure cannot happen.

I guess this really shows my lack of practical experience with these kinds of things. Thanks a lot for going through that.

[MiCarl]

Thanks a lot for going through that.

 

Hey, no problem. Thanks for asking informed, intelligent questions. Trying to explain something helps clarify my own thoughts.

 

Now, a nice Rip Van Winkle style nap is in order........

[Monty]

Remember, if the stator coil shorts, and effectively makes it shorter, then you have less conductor cutting the magnetic lines of force, so your output decreases.

 

Just my 2 cents. I got here late. Good reading here guys.

[James Ardrey]

I do understand what you have explained and I realize what the regulators are supposed to do.

I also realize that you know far more about this stuff than I do, so by me continuing this here, I am not challenging your experience or expertise, I am simply trying to further my understanding by proposing that there may be a little more to this.

 

I also realize the premise here may seem pretty far fetched (this being based on what the dealer had said), but before it gets dismissed here is a thought:

 

Generator/alternators/stators work of the principle of electromagnetic induction (Faraday's law). That is a time varying magnetic field produces an electric field in a conductor. In the case of a stator, the conductor is coils of wire. That is a current is induced in the coils of wire (that make up the stator) at which point the current is 'channeled' off of the coils, through the rectifier (where it is converted to DC) and the regulator where the 'excess' is shunted and then into the rest of the bike.

 

Basic Ohm's law law tells us that V=IR (Voltage = current * Resistance). The coils (on a 2nd Gen) have an internal resistance of somewhere between 0.28 and 0.34 ohms. And the induced electric fields [current] is what is driven - giving rise to the electrical potential energy (ie. the voltage). If there is a sudden increase in the resistance there will be an increase in voltage that ought be taken care of by the regulator/rectifier.

So, if something happened inside the stator, such as two parts of the coil melting together, which could cause an increased resistance this would cause an increased voltage that would then be taken care of by a properly functioning regulator/rectifier. If the rectifier is being overloaded by an improperly functioning stator then it would breakdown and seize to do what it is supposed to do thereby delivering a higher voltage through the system.

 

BUT, before the breakdown of the regulator/rectifier, if there is just slightly more power going through the regulator/rectifier than is supposed to, it may be able to handle it for some period of time but may eventually breakdown due to this being 'overloaded'. So in this case, in between being functional and non-functional the charging system, while being tested solely based on the voltage at the battery (or any other power point on the bike) it would indicate that at that time the charging system is fine, but it would be misleading as the rectifier unit is being overworked and will fail sooner than it would if it was not overloaded.

What I wanted to be sure of was that the stator was functioning as it is supposed to as to not overload the rectifier/regulator and have that go out again. I realize that parts just fail sometimes; albeit from heat, vibration, corrosion, or just 'natural causes'. I just wanted to be sure that there was not something else going on that I was not seeing.

 

I realize that typically stator problems are simply that they stop producing the power that they are supposed to be producing. Since the fellow member told me that his dealer said that the stator was producing more than it should, I was giving him the benefit of the doubt here and trying to come up with a way that it may have happend as well as a way to verify that mine is not doing that. I KNOW this is a big stretch, and sometimes knowing a lot about physics and a little about these specific bike parts is a big disadvantage for me... Especially when I get flustered working on my own bike, :- \

 

Sorry this was so wordy, but that is my thought process here which is not the most probable way for these things to fail, but that was the only way that I could see justification of a voltage spike coming from the stator.

 

When my regulator went out, I heard a gd awful noise out of the speakers and through the audio system while ALL of my lights (that were on) blew out, so when the radio worked fine after I got everything back together I was suprised - so this could be related to that.

What you described re; overcharging stator is exactly what the mechanic stated as the cause of overcharging. Another voltage reg was put in to see if voltage reg was faulty. It had the same symptoms. After the stator was replaced and stereo worked flawlessly. I did have to replace the voltage regulator a couple of months later as the lights were getting bright and dim intermittently. When the voltage regulator was going out it had no effect on the audio system. I don't think the original audio brain was bad in the first place. As I said I think the stator was over charging and overwhelming the voltage regulator. I thought that was a fishy hypothesis myself although I can't argue with success. No problems since stator was replaced. I had never heard of a stator especially in the 2nd over charging, but the mechanic I use is a 20+ yr. veteran @ K &N Yamaha and is an excellent mechanic. He is the only one I trust w/ my bike more than myself.

[LilBeaver]

James: I know you had said taht the regulator was replaced a few months later but about how many miles went between each of these problems? (A guesstimate is perfectly fine).

 

 

What you described re; overcharging stator is exactly what the mechanic stated as the cause of overcharging. Another voltage reg was put in to see if voltage reg was faulty. It had the same symptoms. After the stator was replaced and stereo worked flawlessly. I did have to replace the voltage regulator a couple of months later as the lights were getting bright and dim intermittently. When the voltage regulator was going out it had no effect on the audio system. I don't think the original audio brain was bad in the first place. As I said I think the stator was over charging and overwhelming the voltage regulator. I thought that was a fishy hypothesis myself although I can't argue with success. No problems since stator was replaced. I had never heard of a stator especially in the 2nd over charging, but the mechanic I use is a 20+ yr. veteran @ K &N Yamaha and is an excellent mechanic. He is the only one I trust w/ my bike more than myself.