Stator Life or Death

[00ld Gold]

I'm in the process of replacing my 1st stator (1984-1200 ) and don't want to do this too soon again. I've read two opposing accounts on what causes them to fail ( not the symptoms ) . Some people say that they get too hot from overloading accessories , lights ect. others say they need more load to use up their output so they don't overheat and fail. Does anybody have any real experience in whether I should limit load led's etc. or add more lighting etc . to use up load.

[mrmikey]

Tha stator produces a set amount of current depending on rpm up to it's max, it's either used by accessories or dissipated thru the r/r in the form of heat. Regardless of what you have for load (within reason of course unless you throw on more load than can be supplied) the amount of current it produces remains the same. The only thing putting more accessories would do is prevent heat generated by the r/r as the current generated is being used elsewhere .....Mike

[flash2002]

Hi oold gold, I use to have a 84 gold wing and the stator broke down. I was told that the 84 had a problem with the stator and most of them burn out. I was told to get a stator from a different year, they where better. I saw a sight where they installed a car alternator kit on a 1200 but I cant remember where. Thats a big job, you have to pull the motor.

[FADM Stern GNSF]

There are a lot of misconceptions about stators, but they are not magical items, they can be considered a "Transformer" and nothing more.
Power is generated via a spinning magnetic field (rotor) through an electrical coil (stator). Most bike stators are three phase units to make filtering and charging a lot smoother (either Y ot Delta format).

The stator produces electrical "POWER", and that is why it is listed in "WATTS" at a specific RPM. The voltage is bependent on the RMP (speed of the magnetic field) and the current dependent on load. Lets dispel one really bad myth.

"The stator produces a set amount of current" -WRONG!. The current produced is based on the load attached. The stator will produce more current up to the point its windings overheat and either open up or short to ground.

So, what kills stators ? Stators fail for several reasons, one being normal age and a degeneration of the windings insulation. The main big killer (thats not time) is over current draw on the stator. Heat generated by the engine (even redlining) is no where near the temp that insulation breaks down (over 300 deg C), BUT heat generated by the stator itself CAN surpass these limits. The main cause is over current produced by either a short circuit condition, or a huge load placed on it. The number one cause of high current load is a bad battery. A crappy battery can try to suck many amps (well over the max wattage output of the stator) and cause the stator coild to start generating more heat than can be disipated, causing failure. Most of the time, it because people "think" their battery is OK or good enough, which probably kills more stators than anything else (stator connection to the battery is one of the only wiring sections on the bike WITHOUT a fuse system)

If you want to read a bit more check out the following links on the CX/GL Wiki site

http://cxgl.wikispaces.com/Batteries
http://cxgl.wikispaces.com/Charging+System

While these were written for the CX/GL line, most of the information is the same for the larger goldwings.

If you still want to stick with myths about the stator and batteries, make sure you read the sites "how too" section on stator replacement, as you will get really good at it over time

[mrmikey]

"The stator produces a set amount of current" -WRONG!. The current produced is based on the load attached

I think you could be mistaken, I was always under the impression the stator was maxed out as it was producing current to: 1) either be dissipated as heat via the r/r or 2) thru any applied load i.e. lights, horn, fan etc. Not wanting to cause an argument , just trying to get clarification for myself....Mike

[WingAdmin]

Some very good comments. Just a clarification on how stators are used in our Goldwings.

As mentioned, the stator is just a bunch of coils next to some spinning magnets. The magnets induce electrical current in the coils. In our stators there are 18 coils, but each group of six are wired in series, so effectively there are three coils - which is why the stator outputs three-phase AC current. Three-phase AC is easier to rectify into smooth, constant DC with less noise than the single-phase AC that comes out of your wall socket. It also utilizes the capacity of the wires more efficiently.

In automobile alternators, it consists of the stator (two separate coil windings), a regulator and a rectifier. Instead of spinning magnets, it uses a second set of coils (called the primary coils). Power from the car's battery is used to energize these coils and create a magnet. This magnet (an electromagnet) is used to induce current in the secondary coils. This is why you can't charge a dead car battery with an alternator - there is no power available from the dead battery with which to energize the primary coils, so no magnetism with which to generate electricity to charge the battery. The regulator in a car alternator is built into the alternator itself. The way it regulates the output of the alternator is to vary the amount of power going into the primary coils. The more power going into the primary coil, the higher the voltage and potential current coming out of the secondary coil. This is very efficient, as the alternator only uses as much mechanical energy from the engine as is required to power the electrical load required, regardless of engine speed. As a result, alternators can produce their full voltage at engine idle speed - it simply jacks up the primary coil voltage to compensate for the low RPM.

In our (and most) motorcycles, the stator and regulator/rectifier are separate (In the GL1000, the regulator and rectifier are also separate). The stator consists of spinning magnets and coils. At low engine RPM, the stator makes lower voltage. And higher engine RPM, the stator makes higher voltage, up to around 50 volts AC (per phase leg). The stator is also capable of producing more power (watts) at higher RPM, as it utilizes more of the engine's mechanical energy. There is no way for the regulator to tell the stator how much power the motorcycle needs - so the stator is producing full potential power at all times, for the RPM it is turning. So how does the regulator get 50 volts AC to 14 volts DC?

Well first the rectifier portion of the regulator/rectifier, utilizing a set of high-power diodes, turns the AC into DC. Now we have around 40 volts DC coming out. If we sent that to the bike's circuitry, it would blow things up and cook the battery.

However - as load is applied, the voltage drops. This is important - the more things there are drawing on the available power, the lower the voltage drops. You can see this by putting a voltmeter on a battery, then watching the available volts drop when a heavy load (such as a starter) is applied.

If the battery is severely depleted (i.e. after starting the engine), it can draw tens of amps recharging itself - that's a significant load. If the motorcycle engine is idling, the stator won't be producing enough power to make 14 volts DC, and the motorcycle ends up running off the battery instead of the stator. As RPM increases, the stator produces more power, voltage rises above 14 (actually 13.8) volts DC, and the battery instead of supplying power, starts taking power and storing it.

However, consider this: you go riding, the engine RPM keeps increasing, the battery is now charged and isn't drawing much anymore, the only other loads are headlight/taillight, engine operation, radio and so on. The stator is making more power than the motorcycle requires. If left unchecked, the DC voltage would rise to 40 volts or more - and this would blow lights, cook batteries, and more. This is where the regulator steps in.

The regulator recognizes that the voltage is rising higher than it should, which means there is not enough load to keep it in check. So it has a special component (usually a zener diode) that starts conducting at a set voltage, working as a valve, draining some of the power away, which drops the voltage. However, the power can't just "go away" - it has to go somewhere. So the regulator sends (shunts) it to ground, through a resistor. The resistor heats up, transforming the electrical energy into heat energy, which is dissipated into the air and into the bike's frame. That's that hot spot on the left side of the false tank near your left knee that you feel when riding. This type of regulator is known as a "shunt regulator."

And guess what? That resistor, in dumping energy into heat, presents a load to the stator.

So the stator is under load at all times - even if you disconnected every electrical device, and if the battery was fully charged - the stator is still under load, because the shunt regulator is shunting current to ground through the shunt load (resistor).

In practice, at normal operating speeds, the shunt regulator is shunting current to ground at all times, because the battery is charged and is not requiring any current, and the stator is producing far more power than the bike requires in order to operate. If you add more lights and accessories, adding to the load of the electrical system, you are in reality taking load OFF of the shunt circuit - the stator is still producing the exact same power, and is under the exact same amount of load.

Is it possible to overload your stator? Certainly - if you put six 55-watt lights on your bike, you will not only drain down your battery, but you'll present a very low impedance circuit to the stator and rectifier, which causes the current to rise and causing heat - and as mentioned previously, heat is the #1 killer of stators. However, you will know you're doing this because your battery will be draining.

If you have a battery with a bad cell (or that is sulfated or otherwise bad) that is constantly drawing a large amount of current, this will present a constant large load to your stator, causing it to overheat and shortening its life.

You can also present a large load to the stator if you run extra lights immediately after you start your bike. In this situation, your battery is drawing a lot of current trying to replace what was used to start the engine, and your lights are also drawing a lot of power. In this situation the stator is going to heat up as well. I have a set of driving lights on my bike, but I don't switch them on until after my bike has warmed up - by which time my battery is well recovered.

[mrmikey]

Good explanation, it's the way I was thinking worked, mind you a much better explanation, my compliments.....Mike

[FADM Stern GNSF]

mrmikey, Yes the regulator shunts some POWER to ground, and Wingadmin explained it very well. The main problem is people use "current" as an improper term, when POWER (watts) is the correct one. The stator is NOT a constant current device, but supplies current based on the load. Trust me, put a 1 ohm resistor on the stators lines and it WILL supply a huge amount of current for a short time before melting down.

The regulators on the bike work by "cutting off" the top of the waveform (caps the peak voltage), and thus each of the 3 SCR's only shorts a small bit of power over the whole 3 phase waveform. While the rectifier converts the AC to DC, it also acts as "blocking diodes" to isolate the regulator from the battery side of the system (as the battery acts as a huge capacitor and smooths the DC). If the regulator saw this "filtered" voltage, it would burn out very fast. Since the regulators SCR's "latch on", a steady DC would fry them. They need the unfiltered DC wave so that once the waveform drops below the trigger threshold, they can turn off.

I do understand what people mean when they use the "running full current" all the time, as they really mean power (which is AMPS X Volts), but some can read it as a fact the stator only puts out so much current, which infers its ammune to short circuiting or over current which is not the case. The stator will put out a max power based on RPM, as the current draw goes up, the voltage drops (at a given RPM), so the stator will generate an "amount of power" based on RPM (it is NOT linear, but a curve which has max V and max I).

It may sound like splitting hairs, but I have seem too many people assume wrong and end up replacing their stator.

[mrmikey]

It may sound like splitting hairs,

Not at all, I appreciate the explanations and the clarifications completely. I'm hesistant sometimes to disagree or call someone on their explanation as there are times people (not yourself or anyone here) will take it as an attack on their character.
Personally, I like a good disagreement or civil argument, key word being civil LOL . I've been called and proven wrong enough that I'm used to it ....Mike

[RoadRogue]

I saw a sight where they installed a car alternator kit on a 1200 but I cant remember where. Thats a big job, you have to pull the motor.

It is called the poorboy conversion. You do NOT have to pull the motor to install the conversion and can usually be installed in an afternoon if you are good with your hands and have the tools needed. Just Google "poorboy conversion gl1200" for all the info you could ever want on the subject.

[00ld Gold]

Thank you guys, hopefully now I know more about stators than I will ever need to, if I keep my connections good and most importantly maintain my battery. I am now sure that my battery negligance caused the failure, as after storage I ran a couple of the cells dry without noticing and killed the battery . Maybe I also will ease up on those accessories until battery is fully recovered.

[littlebeaver]

Thank you guys, hopefully now I know more about stators than I will ever need to, if I keep my connections good and most importantly maintain my battery. I am now sure that my battery negligance caused the failure, as after storage I ran a couple of the cells dry without noticing and killed the battery . Maybe I also will ease up on those accessories until battery is fully recovered.

Especially all the grounds at every point... trace them all...check them all...It's my belief, that's the number cause of any electrical failure on parts including the stator...Starts at the frame...I think we have all learned a lot on this day...

[WA9FWT]

A good idea is to plug in your battery tender to your cycle after every ride, and close off the gas valve.
Just good practice.
To prove this saves a battery,and you get life out of it. I Sold a old motor home this spring which I didn't have running in over 5 years.I had a 175MA solar cell placed on top of the roof hooked up to the main battery.I was shocked when I turned the key,and the motor turned over.The battery was in great shape, it started a number of times. Of coarse I had other problems, gas, breaks ect.
I just could not get over after 5 years sitting, how well that battery worked.And this is No Bull either.

WA9FWT Phil

[SilverDave]

Wing Admin has explained it very well. and that load / output is why a dying stator often takes down an almost dying Reg/rect when it dies.

In the GL1200 there are some additional problems...

The stator on a 1200 lives in hot, corrosive oil, and eventually this can eat through the windings ... Recommended fix ? Change your oil fairly often ... its cheaper than a stator install.

Secondly the yellow wire three pin plug near the output, on the left side of the battery is poorly designed.. and often cannot handle the 40 + volts, and starts to " cook" and turn toasty brown. When it is toasted, the corrosion on the plugs of this device increases the resistance here and this can cause even more current draw.
Recommended fix ? hard solder the three yellow wires, and triple shrink wrap them.. It only causes a little hassle if you have to un-solder them for removal.

Thirdly, for 1200's, Electrical Connections make a $50 harness which is made of tougher wire all around , and helps to keep all the connections cool and operating , and supplies a significant increase of power to the coils.

And finally... check and clean the braided wire ground connection from the battery ( its behind the frame, near the starter )... Every additional resistance of this type is increasing the loads on the system.

A stator with soldered connections, in clean oil, with a harness , and good grounds will last for years and years with no problem.. Doing all that brings it back to the way the original honda engineers had in mind.

As WingAdmin said... extra lights are not a problem, if you leave them off until it all warms up.

SilverDave

[Cal-D]

At low engine RPM, the stator makes lower voltage. And higher engine RPM, the stator makes higher voltage, up to around 50 volts AC (per phase leg).

When testing the output of a 1200 stator, minimum voltage should be 55VAC on each leg at 2500 RPM.

[Fewman]

Good info guys. Thanks for the lesson. I do have a question, not meaning to hyjack, I hope...

I replaced the OEM rectifier/regulator setup in my early wing (GL1000) with a Shindengen MOSFET unit, a FH008EB last spring. I have not had any issues with charging or battery, even with two 35w running lights. From the info I obtained while researching this change out, the 'FH008EB' is an FET model vs the old OEM a Shunt/SCR. I believe the Shunt/SCR has been the subject of discussion here. I am under the impression the MOSFET handles the power "more better". How does the MOSFET differ and is it really less prone to damage a stator?

[WingAdmin]

A MOSFET (just like an SCR) is a semiconductor, and in this application, is primarily used to shunt excess current to ground. Without knowing exactly how the circuit is designed internally it's hard to say how the two units differ, but in both cases, the regulators are shunting regulators - it's just the method that they use to shut the current to ground that differs.

[littlebeaver]

If this MOSFET unit works in a 1000, will it work ok in the 1100 or is there a different one for the 1100? This is great information...

[virgilmobile]

Mosfet/SCR......A mosfet typically has a lower operating resistance than a scr.
Lower resistance means less heat and longer life.
This is general terms.4 pages of technical bla bla can be found on any spec sheet.It's just newer,better faster,able to leap tall buildings.....Got to get off the coffee.
I suspect that the 1000,1100,and the 1200 regulating methods could be modified to fit almost anything as long as the initial design is not altered and the parts used comply with the requirements of the charging system.
I could rewire a gl1000 to accept a gl1200 regulator,but I wouldn't try it the other way around.I think the 1200 stator pumps out a bit more than the 1000 regulator system can handle.I'd have to look up the specs on that to be sure.
As with any alterations,you must fit the part to the requirements.Don't just arbitrarily stick in a regulator that wires in the same.Bad things can happen.