Bad Stator?

[sio]

So, found out the battery wasn't be charged the hard way after stopping after a long (1 hr.) ride and turned off the bike. Tried to start the bike and the battery didn't have enough amps to turn the engine over, and I got stranded a couple miles from home at 11p at night.

Here's what I have found out so far but I'm stumped now.

When I start the bike and pull the positive terminal off of the now freshly charged battery it idles perfectly well running only off of the generator. A solid 12.5v coming off of the R/R. When I take it up to 5k RPMs my voltage drops to +/- 9.5vs and all of the instrumentation turns off and on due to the low voltage. I checked the ohms between each coil and they read (+/- .02 ohm) .15 ohms. I also checked each coil to ground which reads a greater than infinity reading so no short on any of the coils. Now coil to coil ohm reading seems to be below spec according to the service manual at .22 - .34 ohms. So I am leaning towards a bad stator. I did replace my R/R initially thinking that was the problem area but with the used but good part in there, I am still producing the same exact problem.

Question is: would that low of a coil to coil ohm reading on the stator mean a bad stator?

Bike is an '07 w/ 12k miles on it.

Thanks in advance for any advice!

 

[Nappa]

Bike is an '07 w/ 12k miles on it.

Just for reference, is that the original battery?

 

[FinalImpact]

Your best bet there is is to pull the cover and look for burned spots. As you noted, a short is a short so now its up to the resolution of your meter to make a decision.

Resistance changes with temperature. Zero the meter if it has that option, measure the different combinations of wires. Now start and warm the engine long enough (10+ min) and turn it off. Repeat the measurements. All tests should repeat with an equal offset in ohms. It won't be much but one with a short to the other won't be as much of an increase as its less windings and less ohms.

PS - DO NOT Jump or charge the bike from a running car. The RR can only dissipate about ~300 watts. A car battery at 14+ volts with much more amperage potential (200A alternators) can destroy the RR. The Stator & RR combo is rated at 25A to run the whole bike so it has limitations and acts as a current shunt when connected to a car...

When the engine is at 3000 PRM, is the RR hot? PS - not sure if pulling the battery from the leads is a valid test. This could be very misleading...

 

[sio]

Just for reference, is that the original battery?

not 100% sure if OE or not. I bought the bike 1.5 years ago used. PO never said anything about replacing the battery.

Your best bet there is is to pull the cover and look for burned spots. As you noted, a short is a short so now its up to the resolution of your meter to make a decision.

Resistance changes with temperature. Zero the meter if it has that option, measure the different combinations of wires. Now start and warm the engine long enough (10+ min) and turn it off. Repeat the measurements. All tests should repeat with an equal offset in ohms. It won't be much but one with a short to the other won't be as much of an increase as its less windings and less ohms.

PS - DO NOT Jump or charge the bike from a running car. The RR can only dissipate about ~300 watts. A car battery at 14+ volts with much more amperage potential (200A alternators) can destroy the RR. The Stator & RR combo is rated at 25A to run the whole bike so it has limitations and acts as a current shunt when connected to a car...

When the engine is at 3000 PRM, is the RR hot? PS - not sure if pulling the battery from the leads is a valid test. This could be very misleading...

I jumped the bike off of a non-running car engine battery (I had seen that advice somewhere in another thread...) I'll warm up the bike to operating temp, redo my measurements, and see whats up. I'll also place the battery back in line with the charging system. I pulled it thinking that I would be able to get a purer voltage measurement from the R/R without the battery voltage on the line as well.

 

[sio]

So after bringing the bike up to temp and leaving the battery in place now rather than pulling it here's what I have:

Battery/Ignition Off: 12.6v
Battery/Ignition On/Engine running @ idle: 12.3v
Battery/Ignition On/Engine running @ 3k RPM: 13.5v

So based off that it does seem that my charging system is working correctly? Just a little lower than spec of 14v.

coil to coil ohms are still at same measurements.

 

[greg]

tbh it sounds to me like a broken R/R

regulator/rectifiers are also fairly cheap, so they would be a good place to start. I believe the R6 ones fit, and tbh I'd expect most modern yamaha R/Rs to pretty much all be the same.

you can measure the AC current with the bike running if you unplug the stator, it should be between 30-90V between each pair of coils (increasing with revs) (and the same on each). I know one of the guys on here doesn't agree with this test, but I think it's useful.

I'd expect at least some charge from the R/R if the stator was broken, as it would have to be seriously damaged to not produce anything, and you've already checked it for continuity.

One other thing to check is the wiring, but I honestly think the R/R just needs replacing.

 

[FB400]

So after bringing the bike up to temp and leaving the battery in place now rather than pulling it here's what I have:

Battery/Ignition Off: 12.6v
Battery/Ignition On/Engine running @ idle: 12.3v
Battery/Ignition On/Engine running @ 3k RPM: 13.5v

So based off that it does seem that my charging system is working correctly? Just a little lower than spec of 14v.

coil to coil ohms are still at same measurements.

These are about the same readings I am getting and I went through a similar problem as you. Difference is much of the techie stuff you posted in the original post makes no sense to me but with the help of FinalImpact and Motogiro I managed to sort it all out. I still can't profess to totally understand ohms, watts, amps and voltage

For the 3 readings you list above mine are just a tad higher at 3k rpm
so..
1: 12.6 volts
2: also 12.6 volts (don't we need 12.8 volts to charge the battery? this worries me still)
3. 13.7volts which is actually achieved in lower than 3k rpm. Really closer to 2200-2500 rpm (calling nonsense on those that say you need to rev to 5k to get full power - multimeter says not true).

The first time my battery couldn't start the bike I had ridden home in heavy traffic for period of about 35 minutes - about 1/2 of that time idling and not moving and the fan on. The fan really consumes quite a bit of juice. I was able to easily push start and get home.

The second time was earlier this summer. Very bad traffic jam and idling for 15-20 minutes with the fan running most of the time. The Check Engine Light came on and eventually threw out the code of 46 which means the charging system was not putting out enough juice.

Changes I made.
1. Swapped out the dual 55 watt ballasts for 35 watt ballasts. 55 watts x2 is a bad idea on these bikes. I know lots of you run the dual headlight mod 55watts x 2.. just sayin'.
2. I wired in toggle switches to enable cut out 1 or both headlights in the case of dire emergency. Probably an overreaction of sorts but in the event of a closed road and no way to get off it this could save my battery. An alternative could just be to shut the bike off if idling for an extensive period of time.

So far it has been perfect although not alot of traffic jams to test with.
Also an occasional blip of the throttle when idling can bring the stator output up almost 1 volt - enough to keep charging the battery.

Sorry for the long post. Just describing a very common occurrence amongst FZ6 owners and some possible things to make this better

 

[sio]

tbh it sounds to me like a broken R/R

regulator/rectifiers are also fairly cheap, so they would be a good place to start. I believe the R6 ones fit, and tbh I'd expect most modern yamaha R/Rs to pretty much all be the same.

you can measure the AC current with the bike running if you unplug the stator, it should be between 30-90V between each pair of coils (increasing with revs) (and the same on each). I know one of the guys on here doesn't agree with this test, but I think it's useful.

I'd expect at least some charge from the R/R if the stator was broken, as it would have to be seriously damaged to not produce anything, and you've already checked it for continuity.

One other thing to check is the wiring, but I honestly think the R/R just needs replacing.

Yeah, that was my first thought, a broken R/R. I bought a used (OEM) but good one off of ebay since I didn't want to drop the coin on a brand new one. Both the old one and the ebay one produced the exact same results voltage wise. That's what leaned me towards something else like the stator.

 

[sio]

These are about the same readings I am getting and I went through a similar problem as you. Difference is much of the techie stuff you posted in the original post makes no sense to me but with the help of FinalImpact and Motogiro I managed to sort it all out. I still can't profess to totally understand ohms, watts, amps and voltage

For the 3 readings you list above mine are just a tad higher at 3k rpm
so..
1: 12.6 volts
2: also 12.6 volts (don't we need 12.8 volts to charge the battery? this worries me still)
3. 13.7volts which is actually achieved in lower than 3k rpm. Really closer to 2200-2500 rpm (calling nonsense on those that say you need to rev to 5k to get full power - multimeter says not true).

The first time my battery couldn't start the bike I had ridden home in heavy traffic for period of about 35 minutes - about 1/2 of that time idling and not moving and the fan on. The fan really consumes quite a bit of juice. I was able to easily push start and get home.

The second time was earlier this summer. Very bad traffic jam and idling for 15-20 minutes with the fan running most of the time. The Check Engine Light came on and eventually threw out the code of 46 which means the charging system was not putting out enough juice.

Changes I made.
1. Swapped out the dual 55 watt ballasts for 35 watt ballasts. 55 watts x2 is a bad idea on these bikes. I know lots of you run the dual headlight mod 55watts x 2.. just sayin'.
2. I wired in toggle switches to enable cut out 1 or both headlights in the case of dire emergency. Probably an overreaction of sorts but in the event of a closed road and no way to get off it this could save my battery. An alternative could just be to shut the bike off if idling for an extensive period of time.

So far it has been perfect although not alot of traffic jams to test with.
Also an occasional blip of the throttle when idling can bring the stator output up almost 1 volt - enough to keep charging the battery.

Sorry for the long post. Just describing a very common occurrence amongst FZ6 owners and some possible things to make this better

Thinking back, I was riding when I was riding that day, I was in stop and go traffic, with both headlights on. 35w lamps is a good idea. That way I can get away with both lights on so people stop coming up and telling me one of my headlights is burnt out!

 

[greg]

i'd try measuring stator output with the bike running and it unplugged.

not sure how easy it would be to check the R/R output with it disconnected from the battery, but that would be a useful check too

it is also possible that the spare R/R you bought is broken, or that there's a problem with the wiring.

i'd start at the stator and work your way through the system step by step

also FWIW you should be getting 14.0-14.5V across the battery when it's charging. 12.6 is too low


edit: actually reading back if the charging voltage is increasing slightly with revs then the stator could be to blame.

also check my guide out if you want to re-wire it yourself to save some cash (though if you can afford it, then it's much easier to buy a new one!)

 

[FinalImpact]

SIO, the output numbers you posted seem typical. There is a chance you simply fixed a bad connection an all that happened was coincidental from dual head lights, the commute that day and *maybe* that bad connection.

Repeat your charge test with one light disconnected and chances are it matches what other report (compare apples to apples).

I think the misleading part is yamaha spec'd the magneto coil output as max at 5000 RPM in the FSM and it has been shown the RR makes full use of it at less than 3000 rpm. Also, because it uses fixed magnets, its really a magneto but it in layman's terms it produces AC current like an alternator.

PS - Unlike a car alternator, these put out FULL CURRENT all the time (because of the fixed magnetic field) and the voltage goes up with engine speed. Any unused current not used to run the vehicle, charge the battery or power an accessory is dumped into the RR's current shunt and passed off as heat.
- A car on the other hand increases the field coil strength to get more current & voltage from the stator (I don't recall the exact configuration but its something like that). Its why it takes some battery energy to make a car alternator produce energy (you must make an electromagnet first) and our bikes make power just from spinning the crankshaft (fixed magnets).

Also, most batteries will have a manufacture date stamped on them. It could be this is the original and its seen better days as far as amp hour capacity.
FWIW: mine is the original from Jan 2008, bike was purchased by the first owner Aug 2008, so it was placed into service between those dates. I don't trickle it, just park it and disconnect the leads for 3 months.

Another blah blah blah session by yours truly...

JJD952

 

[PhotoAl]

Doesnt look like you have a bad stator. I had one and replaced the battery the regulator the stator my heart valve ... and it was fixed!

I had one coil burned and the battery voltage was 12.8 or so at 5,000 RPM. Replaced the stator and the charging voltage was 13.9 with the old RR and 14.1 with the new RR. Left the new RR in and the charging voltage (5,000 RPM) dropped to 13.9 after a few days of riding. My bike had the dual headlight mod and was fine for almost 4 years till the stator went. I'm a little suspicious of your stator but the voltage seems too good for it to be the problem. Best way to check is open it up (carefully so you don't mess up the gasket) and check. My stator had lots of cracks in it (2004 with almost 40,000 miles) and was probably due to fail.

If you do replace the stator it is pretty easy EXCEPT for the three bolts holding it in. Make sure you have a good torx it and use the best technique to loosen them - hold the wrench vertical and don't let it slip or lean over. I put everything back together with red locktight.

 

[Motogiro]

i'd try measuring stator output with the bike running and it unplugged.

not sure how easy it would be to check the R/R output with it disconnected from the battery, but that would be a useful check too

it is also possible that the spare R/R you bought is broken, or that there's a problem with the wiring.

i'd start at the stator and work your way through the system step by step

also FWIW you should be getting 14.0-14.5V across the battery when it's charging. 12.6 is too low


edit: actually reading back if the charging voltage is increasing slightly with revs then the stator could be to blame.

also check my guide out if you want to re-wire it yourself to save some cash (though if you can afford it, then it's much easier to buy a new one!)

I don't disagree with a current/voltage test of the stator while running and disconnected from the bike but....You should have a specific load on each branch that you are testing. Testing voltage into a very high impedance such as a multimeter and no known specific load for the test is not the ideal way to test if the windings have integrity. If you want to see it as a 'Go/No go test that's okay but it will not give a specific value to establish the winding produces voltage under load. This means you have no current value. just voltage. If you test the stator at 3000 RPM and then test it at 7000 rpm into a voltmeter you don't know the specific frequency and waveform or the Q factors your dealing with to do an accurate test. What your meter says can and most likely will be different than most others that would do the same test the same way without a known load. This is the reason for the resistance test. The Ohms resistance test is a DC test and is not related to alternating current measurement, with it's known variables and it is not load specific. Are resistance tests fallible? Yes but in this case the resistance test is better and will in all probability yield the information needed to trouble shoot the charging system.

As with any of these problems, check the obvious first. Loose connections including battery terminals. Check the RR connectors/plugs and inspect for damage from overheating or mechanical contact/pin failure.

Do not disconnect the battery from the vehicle while the engine is running. This was an old school trick from back in the days of car generators. Today's electronics can be damaged by spiking and over voltages when the system has lost the battery. In fact the RR diodes may not be able to deal with full boat energy from the stator. Solid state devices are very unforgiving in those conditions. Each part of the charging system is symbiotic and dependent to a whole healthy system.

I hope this explains some of why I say to do it a certain way. It's not just my opinion but there is is in fact some knowledge and experience attached. Good luck and happy hunting!

PS. I've never heard of it happening with the FZ6 but some charging systems on bikes have failed because the permanent magnets let loose and no longer spin with the assembly.