Stator problem!

[GAS]

Hello guys!

I've had problems with a dead battery last week, I charged it out of the bike and it looks like it's good. I've checked the alternator and it's resistance is good (infinite between ground and any of the 3 cables and almost zero between the 3 cables).

But with the engine running at 5000RPM the output voltage is only 69v between the 3 cables (pair to pair) when it should be at least 75v. When measured at the battery the voltage at 5000RPM is only 12.9v and should be between 13.5 and 15.5v. My battery probably died because it's not being charged properly.

Should i replace the stator, only? If so, is it ok to recoil the old one? A used one at ebay is not that cheap (at least 70bucks shipped, and can be as bad as mine), and a new one here in Brazil is freaking expensive while it should cost about 30 bucks to recoil my old one. And more: Can I be sure that recoiling the stator I will have at least 75v that I need?

Tks!!

[The Buddha]

I may be the only one here to have ever re wound a stator - I would seriously not recomend it ... but it can be done.
Hand wound 30 turns per pole 3 phase and take care to wind it tight, the first layer will go on smooth and even, but past that is where it gets very very hard especially the last set of poles. If you want to know more ask and I'll post what I remember. I had a lot of time, and no $ and no job when I did it and it was a larger stator than a gs stator so it will be harder on a GS stator.

I can prolly sell you a good used one ... so would some others here prolly .... but your call.
Enamelled copper wire and high temp epoxy is almost available cheap in any country in this world.

Cool.
Buddha.

[GAS]

Tks Buddha!

Actually, that 30 bucks I said before is for me to pay someone else to rewind the stator. Here we have stores that just rewind electrical engines, starters and alternators. They should know how to rewind it, but your information about how many turns it takes was precious!

If you have a good stator to sell, how much would it cost? Maybe could be better than rewind my old one (Maybe a stock one would be better, I just don't know).

Just to make sure:

My bike is a '97 with 40k miles on it. Is it normal to have a faulty stator in these conditions?

I'm assuming that the 69V measurement is totally caused by the stator. Is there something that could affect the reading other than a bad stator?

Tks for your help!

[The Buddha]

Yea your low voltage could be a result of magnet losing power.
You should check resistance on the stator wires too.

30 bucks - in brazilian money ? how much is that in $, cos I'm sure there is a whole horde of gs'es which have eaten the stator from goats and hence will need stators wound. Not only will you wind yours, you would start a surge in reverse where we send our stators over there.

I am near about sure its gonna be 25 atleast to send the stator over there.

Its a 3 phase, 18 pole, 30 turn stator if I recall. You wind it every 3rd pole at a time and then you crimp them together at the inner side, and outer side goes to the wires out of the thing into the wiring harness. The thing is, you could use enamel coated, heat activated epoxy dipped wire and after you're done heat it to the cure temperature (about 350 or so) and it bakes on the epoxy. However enamel coated and epoxy dipped after the winding is fine too.

Put in an extra 1-2 turns for a more powerful one. Put in less turns for easing the heat sink.

Cool.
Buddha.

[GAS]

Every "bucks" I said before are US$, so you can compare!! It should be relatively cheap to rewind it here. But it's not usual to rewind bike's stators, so I don't know if I really will find somebody to do the job.

I've mesured the resistance and all values are normal.  "I've checked the alternator and it's resistance is good (infinite between ground and any of the 3 cables and almost zero between the 3 cables)." This could mean I have a problem with the magnets? The strange thing is that I haven't seen a single magnet for sale at Ebay, so I didn't think it would need to be replaced someday.

I'm getting confused now! Really, really confused.

About sending stators to rewind here, the only problem is that it would cost a small fortune to be sent back to the US.... Actually it would cost something like 7 bucks to be sent from US to BR, but the way back would cost something like 50 bucks...

tks again!

[sledge]

Its a six pole design, it has a synchronous speed of about 1000-1200 rpm and provides AC at about 50-60hz.
Yeah there are 18 coils but you need to divide those by 3, one for each phase. It gives you 6. Wire diameter is as critical as number of turns. Its ok to go up a size if the pole pieces can accomodate the extra volume as this will reduce electrical losses but DONT go down in size or reduce the number of turns. This will increase electrical losses, the winding will operate at a higher temperature as a result and its insulation life will be reduced. Idealy it needs to be wound with what is known as Amalgamation or self-bonding wire. This will ensure each turn is firmly bonded to its neighbour after the winding has been impregnated with varnish and stoved and this will reduce the risk of insulation damage due to vibration. If they have the facilities and can VPI it, thats impregnation under vaccum follwed by pressure even better as this will ensure varnish reaches all the voids in each coil.

If your rewind shop has a surge tester, and most well equipped shops do they could easily test the integrity of your stator winding. Problem is its wound with relatively heavy wire and there is very little resistance there to start with. The average 9/12v multimeter is just not accurate when it comes to measuring low resistances. A Surge tester applies a high voltage for a fraction of second to the winding, records current, resistance, insulation resistance etc  then analyizes the results. They can detect just one inter-turn short in a winding. If they dont have a surge tester they should have a Ductor. This is an instrument that can measure low resistances and provide far more accurate results than a multimeter can. What you are looking for is a substantial difference in resistance between each phase rather than a balanced but slightly lower figure between phases than manufacturers spec.

[GAS]

Tks for helping me out!

I'm searching for an used Stator and rotor in better conditions than mine because I believe my one is probably faulty.

The last question, the 69v coming from the alternator are surely making I only have 12.9v at the battery poles (both with 5000RPM) ?


Some guys told me that it could be caused probably by a faulty battery. But I don't know, my battery is pretty new (7 months old), and I can't understand why a faulty battery would interfere with the voltage at its poles with the engine running at 5000RPM.


Is it smart to replace my stator/rotor in this case? Or should I start replacing the battery? Remember that in my  case the battery will cost twice as a working stator/rotor.


I, personally tend to replace the stator more than the battery....

[sledge]

The majority of charging issues are caused by a faulty battery, I would have it load tested by an auto-electrician before replacing anything else.

[GAS]

It was "slow-charged" (I don't know the right term in English) and tested by an auto-electrician. He told me the battery was good, just "uncharged" !

A fact that may help: When riding, at any RPM and time, the lights (head an tail lights) are flickering a bit.. This is the main fact that makes me blmae the alternator, besides the low voltage coming from it.

What do you think?

[lamoun]

But with the engine running at 5000RPM the output voltage is only 69v between the 3 cables (pair to pair) when it should be at least 75v. When measured at the battery the voltage at 5000RPM is only 12.9v and should be between 13.5 and 15.5v. My battery probably died because it's not being charged properly.

Should i replace the stator, only?

Nah.. it's the regulator.

I don't have my measurements on hand, but my stator also gives me less than 75V, no problem with the battery.

[sledge]

Flickering lights?? now you tell us........yeah I agree..... its the reg/rect.

[The Buddha]

Just add in the R/R to the rotor/stator combo ... swap it all in 1 sweep.
And when you get the R/R out, put hex head bolts in the thign instead of the awful phillips ones locktited and torqued to 300 lb at the factory.
Cool.
Buddha.

[GAS]

Flickering lights?? now you tell us........yeah I agree..... its the reg/rect.

I'm gonna do like buddha said, I'll try to replace everything in one step! I've heard before about some alternator giving less than 75v and everything was working good, but, I also heard that R/R's hardly have problems giving less voltage, usually the fault giving 16v, not 12v...

I'll swap everything and I hope the problem to disappear!!

[The Buddha]

16V, yea been there, battery will boil and swell and burst and will often cook the water out first.
Cool.
Buddha.

[GAS]

Yeah your battery go to battery's heaven...

I tried to say that usually when a R/R goes bad the output voltage goes high rather than goes down... I'm my case the voltage went down, what is a little bit strange, but at least I still have a battery.

[The Buddha]

Oh the other thing is with R/R failure you will get AC across the battery too, and that actually is way worse for the thing and it can kill your spark as well cos the coil needs a short burst of proper DC to setup the spark.
Cool.
Buddha.