How Do You Diagnose Rectifier Failure?

My battery on a trickle charge goes over 13 volts - but after riding an hour - when I turn the engine off - the battery is dead - won't turn the engine. Then, if I get a jump - the Swing runs fine as long as I am moving - but when I turn it off the battery is dead -again. When I measure the charging voltage (at any rpm) with a voltage of 12.8 volts the battery voltage drops to 12.2 volts and reving the engine makes no difference - it is the same as the batter voltage (i.e., battery is not charging). It seems to me that this points right to the Rectifier being the problem; but I am not savy with electrical issues. My wiring diagram has 5 wires going to the rectifier (not counting the 3 yellow) - 2 red, 2 green,1 black - which is the same as the connector on the SWing. There is one check in the Service Manual than states for cheking the Battery Line: Measure voltage from the R/W to Ground - there should be voltage at all times. I am confused about the R/W wire (there is no red-white wire) and 'at all times' - what 'all times'?

Any advice appreciated. Thanks.

I am not sure but I believe that a fully charge battery should register around 13.8 when in new condition have you tried checking the battery after the battery has been charge 24 hour if the reading is the same reading .Your battery might be to week to keep a full charge or your swing is over loaded with mods. get the battery tested it will tell you the condition on a load test.

when charging (either on or off SWing) you should be showing a voltage somewere in mid 14s. Tinman is right about the resting voltage.

there is only elimination test for Rectifier/Regulator-if you have the correct inputs and incorrect output, then it's bad.

WO/ my manual handy I can't give exact numbers, but those 3 yellow wires from the stator should be showing something in range of 70-85 volts AC. That's when running, measured between each of them.

" My wiring diagram has 5 wires going to the rectifier (not counting the 3 yellow) - 2 red, 2 green,1 black - which is the same as the connector on the SWing. "
Sorry needs the manual

'at all times' - what 'all times'?
whether the keyswitch is on or off

Thanks Guys for the input as every bit helps. Here is what I know - and what I am going to do (unless someone has a suggestion).

WHAT I KNOW
Got a new battery and trickle charged each - both Battery Voltages (BV) were in the 13.5 to 13.1 range - used the new battery for my test. Put the battery in (with connected fairing - meaning high beams on) the Swing and measured the BV as 12.87 V with key off and 12.31 with key on. Started the engine and measured the BV as 12.36V (should be over 14V) so something is amiss. Measured the resistance between the Stator wires (3 yellow ones) and things were in spec. Measured the continuity and found all stator wires connected to ground (should have had no continuity). Checked the wiring harness diagnostic and all was OK(except for that continuity check noted above). Turns out the 2 red wires (they are not R/W as noted in my manual) go directly to battery (through a fuse) so they are always hot - and measument confirmed they were at BV. Measured the two green wires (which go directly to ground) and they indeed are at ground. Not sure what the black wire is for - but there was no test for it. Measured the voltage between each of the yellow wires going to stator - they were each at 2.5V with each other - not sure what this test means.

Conclusions: I conclude that my stator is bad and maybe my alternator is bad (based on discussion under other topics on this forum) as there seems to be no way to check out the alternator with a bad stator and that the alternator can be the root cause of a stator failure.

WHAT I PLAN TO DO
Replace the stator ($200) and then run the engine in my garage and measure the CV - and if the CV is in the range of 14.5 V then I don't need to replace Alternator? HERE ARE MY KEY QUESTIONS: 1)DID I MISS ANYTHING?; 2) WHEN I MEASURE MY CV IS THERE A RECOMMENDED UPPER LIMIT AND WILL THE CV TELL ME IF MY ALTERNATOR IS BAD?; 3) IF THE ALTERNATOR IS BAD WILL THIS SHORT TEST BURN UP MY NEW STATOR? Many thanks again.

Not sure if you did but on tick over the voltage on mine would be 12ish rising to 14ish when the revs are about 1400.

Hello RArch,
The full voltage data set included:
13.10 battery disconnected
12.87 battery connected - key off.
12.31 key on - high beams.
12.34 idle
12.41 2000 rpm
12.45 3000 rpm
12.36 5000 rpm

If I disconnect the front headlights (i.e., no lights on at front end) the data looks better - but this mode of operation is not realistic:
12.95 idle
13.57 2000 rpm
14.25 3000 rpm
14.28 5000 rpm

Regulator failure *usually* makes too high of a charging voltage.

Stator failure *always* makes too low.

Of course either could be at fault, but I would bet on stator.

Dimond wrote:

Thanks Guys for the input as every bit helps. Here is what I know - and what I am going to do (unless someone has a suggestion).

WHAT I KNOW
Got a new battery and trickle charged each - both Battery Voltages (BV) were in the 13.5 to 13.1 range - used the new battery for my test. Put the battery in (with connected fairing - meaning high beams on) the Swing and measured the BV as 12.87 V with key off and 12.31 with key on. Started the engine and measured the BV as 12.36V (should be over 14V) so something is amiss. Measured the resistance between the Stator wires (3 yellow ones) and things were in spec. Measured the continuity and found all stator wires connected to ground (should have had no continuity). Checked the wiring harness diagnostic and all was OK(except for that continuity check noted above). Turns out the 2 red wires (they are not R/W as noted in my manual) go directly to battery (through a fuse) so they are always hot - and measument confirmed they were at BV. Measured the two green wires (which go directly to ground) and they indeed are at ground. Not sure what the black wire is for - but there was no test for it. Measured the voltage between each of the yellow wires going to stator - they were each at 2.5V with each other - not sure what this test means.

Conclusions: I conclude that my stator is bad and maybe my alternator is bad (based on discussion under other topics on this forum) as there seems to be no way to check out the alternator with a bad stator and that the alternator can be the root cause of a stator failure.

WHAT I PLAN TO DO
Replace the stator ($200) and then run the engine in my garage and measure the CV - and if the CV is in the range of 14.5 V then I don't need to replace Alternator? HERE ARE MY KEY QUESTIONS: 1)DID I MISS ANYTHING?; 2) WHEN I MEASURE MY CV IS THERE A RECOMMENDED UPPER LIMIT AND WILL THE CV TELL ME IF MY ALTERNATOR IS BAD?; 3) IF THE ALTERNATOR IS BAD WILL THIS SHORT TEST BURN UP MY NEW STATOR? Many thanks again.

1. any resistance is bad
2. one of my Hondas was running near 15v, I monitored batt.,but never seemed to do anything
3. I don't see how the rotor could generate a higher voltage that would damage your new stator. A mor likely damage would be that something slipped or wore allowing striking.
You would see this as grove or scrape when you remove the old stator.

here is short article frm electro on stators-
http://www.electrosport.com/technical-resources/technical-articles/motorcycle-stators

I see that Rick's will rebuild existing stator as the optional higher output (assuming that's what SS-20 means). BUT 1mo. turnaround

Dimond, from your information-"Measured the continuity and found all stator wires connected to ground", you need a new stator. When you pull your old stator you will find at least one of the coil windings will be burnt. When you replace your stator you will have over 12.5v at idle and when you raze your RPMs over 3,000 you will have over 14v. If you have 15v or more at 5,000 RPMs then you will need to replace your Rectifier/Regulator, but I would be surprised if your Rectifier/Regulator is bad. Your stator is your alternator it puts out an AC charge your Rectifier/Regulator converts it to DCv and anything over about 14.8v DC will be sent to ground and be lost as heat. Not long ago I went through this same thing, replaced my stator and all is fine now. When you replace your stator and check your voltage I am confident that you will find all will be fine. Then when the next person asks what to do you will be able to pass along what you have learned. What surprised me the most was the thin layer of silicone on the cases, they are machined to such a close tolerance that no gasket is needed. I was impressed at the quality machine work Honda has done on those cases. Don't forget to drain the oil before you pull the case off.

Thanks everybody! Today's mission - pull the stator!

model28a wrote:

When you pull your old stator you will find at least one of the coil windings will be burnt.

Pulled the stator and found one pole burnt and one looking like it is on the way to being burnt - rest of the poles look new. So, bad stator. Who has the best online Honda SWing part prices these days (from a reliable source)? Thanks to all for getting me this far - but not done yet.

Here's one.
http://www.partzilla.com/parts/search/Honda/Scooter/2008/FSC600D+AC/GENERATOR/parts.html
Here's another.
http://www.motogrid.com/pages/OemParts?aribrand=HOM#/Honda/FSC600A_AC_(08)_MOTOR_SCOOTER%2c_JPN%2c_VIN%23_JH2PF014-8K500001_TO_JH2PF014-8K599999/GENERATOR/FSC600A-08-JPN-AC/2Y14MCT6MCTAE0900A

I believe that all years of Silverwing use the same stator. The Honda part number for my 05 stator is 31120-MEF-003.

Bike Bandit has that stator for $197. Cheap Cycle Parts has that stator for $194. Both offer free shipping. I have purchased parts from both vendors with good results.

Electrosport makes good aftermarket stators for Honda's. They are about $120 but I didn't see the Swing listed.

Good luck with your charging problem.

The 'burnt' coil (photo attached) is the one under my fingertips. I am guessing that stator failure is fairly common based upon: response to my post; other forums; and the fact that there seems to be a robust aftermarket stator rebulid market. Do you think stator failure is fairly common? And if so, the cause/cure?

When I took off the right crankcase cover both the idlle gear/shaft and the reduction gear/shaft came out attached to the cover. When I re-install them do the teeth have to line up in any particular fashion? I am guessing not - but would rather not guess. Thanks.

When my stator burnt out on my 750 shadow It was completely dark brown compared to the copper colour of the new stator. Could you take a picture of the new one side by side with the burnt one.Is there a test reading that one can see the different reading to compare.

Used my IPhone and the picture did not come out too well. I will try to use another camera and provide a better photo. Visually, only the upper half of the single pole under my finger looks bad, all the others look shiny new.

Dimond I think your picture is pretty good, but I have seen what a burnt stator looks like before. It may not be so obvious to someone who has not seen one in person.
As to your question."Do you think stator failure is fairly common? " My guess would be no. We have a lot of Hondas in are local club (at least 6 or 7 Silverwings) and I have only seen one Reflex and my own Silverwing that had the stator go out. Why did they fail? Your guess is as good as mine. I worried that my new one would go bad and for a long time. I carried a voltmeter around with me and kept a close eye on my power output until I was sure the stator was not going to go bad. I had around 38,000 miles when it went out and now have over 43,000 mi so I think it's fine. What was your mileage when yours went out? I bought a new one before I took my old one out so I would not have to ride my Morphous while I waited for the new one. I ride my scooter as my main transportation.

The 2008 stator failed at 24000 miles. My 2003 had about 35000 miles on it before I got the 2008 - without a failure.

Replaced the stator and all is well! The rectifier seems to work fine - so not going to replace it. Thanks again for all the provided input.

Glad its sorted

I've skim read the previous posts but didint see an answer. Was it possible to replace the stator without taking the engine out?

You don't need to pull the motor. The procedure is simple in the service manual. It would take me a long time to type out. I type slow.

Take out the tail pipe from underneath. Drain your oil. Take all those screws out. Put something underneath cause it will drip some more. Oh by the way. there are 2 little gears things when you pull the side off. Remember where they go. There is no way you can't screw this up.

You will see the alternator/stator. take that sucker out. When you put it back make sure you have some of that seal in a tube high temperature ( mine was orange) and that's about it. It may look overwhelming but is not. Legos ?

Easy. I had no experience and no manual on how to do it. Installing the pipe underneath was a little hassle at first. Wiggle is your friend.

I could be mistaken, but I don't remember taking out the tailpipe from underneath.

There are a couple of screws at the bottom that are blocked by that tail pipe. I personally couldn't get to them unless I took the whole thing off. You may have better luck than me.

L