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Author Topic: Alternator probems  (Read 252 times)

creaky

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Alternator probems
« on: February 03, 2015, 08:10:38 AM »
I Have a 2006 Bullet 500 iron barrell, electric start. I had to replace my stator and roter. I bought a complete alternator from India for $30.00. Sounds good but it only charges the battery at about 300 milliamps. Thinking it was faulty I contacted them and they sent me another stator. I checked the resistance of the two coils with the suspected faulty one and they are identical. Installed the new one in the bike and still only a small charge. I have read that I should get around 50 volts AC from each coil when isolated from the rectifier. (all 4 wires disconnected). I am only getting around 30 on one coil and 24 on the other. Any ideas? I have a lot for info if anyone has questions.

High On Octane

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Re: Alternator probems
« Reply #1 on: February 03, 2015, 11:35:19 AM »
How big is the air gap between rotor and alternator?  It should be about .009 all the way around.  If it is bigger than that it can cause weak charging.  Why did you replace the rotor too?  Those generally don't go bad.
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AgentX

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Re: Alternator probems
« Reply #2 on: February 03, 2015, 04:41:24 PM »
I once mistakenly set up the four-wire output with the wires paired incorrectly going to the R/R and had the same type of symptom.

creaky

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Re: Alternator probems
« Reply #3 on: February 05, 2015, 10:04:39 AM »
Why did I replace the roter? Good question. It was my fault. I was not careful enough fitting the perfectly good stator after replacing my sprag clutch. (The sprag job worked out perfectly and only cost $100) But I forgot about adjusting the position of the stator and just bolted it on. After a short ride I noticed it was not charging and a bad burning smell. Took the cover off to be greeted by chewed up roter and stator. I now know how to get that gap right and find the best method is to wrap a plastic strip from the bottom of a $1.00 shopping bag round the roter, slip the stator on and tighten the three nuts carefully, checking the plastic has even tension all round. If not, a slight tap with a hammer in the right direction and then remove the plastic. The gap on mine is perfectly even and I guess about .45mm as that is the thickness of the plastic. But if you say .009, if you mean inches, that converts to .22mm so my gap is too big by a smidgeon but there is no way to adjust it. What do you think?

creaky

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Re: Alternator probems
« Reply #4 on: February 05, 2015, 10:15:53 AM »
Hello AgentX
I have the 4 wires correct. In the stator the violet wires go to 3 coils of light wire in series, each coil being about 1 ohm so the resistance between the violet wires is around 3 ohms. The orange and yellow wires go to 3 coils of heavier wire in series, each about .3 ohms so the resistance between orange and yellow is around .9 ohms. We should get well over 30 volts AC across the violet wires when revving the motor (with the wires disconnected from the rectifier). The orange and yellow just supply AC for the headlight with an AC regulator across the output to keep the voltage down around 12.5 volts AC. This is my take on the whole setup. Not rocket surgery but I'm still kicking myself for stuffing my original alternator.

AgentX

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Re: Alternator probems
« Reply #5 on: February 05, 2015, 05:12:35 PM »
Ah.  I forget about the AC light setup.  I was running DC-only when it happened to me.

creaky

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Re: Alternator probems
« Reply #6 on: February 05, 2015, 09:01:08 PM »
AgentX
Are you in a position to disconnect the 4 wires and put an AC voltmeter between the violet wires, rev the engine and tell me the voltage you get and then do the same with the other pair of wires. I have read somewhere that this should exceed 50 volts AC but Hitchcocks say 30 volts. Of course, once you reconnect the wires that voltage will be less due to the load of the rectifier/regulator and the AC regulator even with the headlight off. Also, an easier reading to take would be a voltmeter across the battery, rev the engine with lights off and see if the voltage rises over 13 volts. Mine goes to about 12.8. Hope to hear from you or anyone else who can supply that information. I suspect the cheap ($AUD$61.00 delivered to Australia) alternator I bought from India is out of tolerance in that the diameter of the roter is about 2mm too small, giving me an airgap of about .5mm instead of the required .22 mm as High on Octane suggests. Do you think that small amount would make a difference.

singhg5

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Re: Alternator probems
« Reply #7 on: February 05, 2015, 10:50:46 PM »
Are you in a position to disconnect the 4 wires and put an AC voltmeter between the violet wires, rev the engine and tell me the voltage you get and then do the same with the other pair of wires.

I have read somewhere that this should exceed 50 volts AC but Hitchcocks say 30 volts. Of course, once you reconnect the wires that voltage will be less due to the load of the rectifier/regulator and the AC regulator even with the headlight off.

In one of the videos an iron barrel RE alternator output was recorded up to 45V AC as the engine was revved up.  It is very likely that the output would have gone even higher at higher rpms. Is this bike / alternator similar to yours ?

 https://www.youtube.com/watch?v=xUCvZlOPPf0   
« Last Edit: February 05, 2015, 10:53:03 PM by singhg5 »
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Kevin Mahoney

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Re: Alternator probems
« Reply #8 on: February 06, 2015, 01:22:26 AM »
I have seen 45-50 volts AC. There are also replacement alternators and the there are replacement alternators. I have seen it all and you get what you pay for. I only use the ohm meter on the iron barrel stator to check for shorts and continuity.

I have always used the voltage test just to see if it is putting out electrons in reasonable quantities. There really isn't an absolute spec. I would say no less than 30 and even that might make me suspicious but I would move on it's ability to charge

At the end of the day the point is whether or not it is charging the battery. Is your headlight as bright as it was before? When you have the lights on (I know it is an AC system but the taillight, dash lights etc. are not can you get 14.5 - 15 volts constantly?
If so I would call it good.

There is an spec for the alternator/stator gap. You might have noticed however that there is not much adjustment. The two important points are to make sure initially that it is centered. Your use of plastic (cut up bleach bottle works too) is a good way to do this. However an oft overlooked step which is critical is to rotate the engine and measure between the rotor and stator in several places. This is why we sell brass feeler gauges that are not magnetic.   Rotate the rotor to several places and measure all of the way around.

What you are really looking for is to make sure that the run-out of the crankshaft/rotor does not cause the rotor to touch or get too tight as it operates. All iron barrels have this. You will never get it perfect but it's OK, take a deep breath, this engine was designed in the 1940's and was built to do the job, not satisfy our need for exact specifications. EFTI is a different matter.

creaky

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Re: Alternator probems
« Reply #9 on: February 06, 2015, 06:22:44 AM »
Hello Singhg5 and Kevin, I have seen that Youtube video and he talks about a voltage above 30VAC which I just have but Kevin hit the nail on the head I'm afraid. You get what you pay for.(sometimes) I bet the expensive ones from Hitchcocks probably have more windings or something. I know there are only 6 coils but the quality of manufacture may be important here. I will see how mine performs and I am lucky in that my Bullet has a sidecar and in it I carry an old car battery and jumper leads to get me home if necessary. Kevin, my headlight is sort of bright enough but I can only get 12.7 volts DC across the battery when I rev it up so that's not right. I must measure the AC across the headlight when it is on. It should be regulated at around 13 VAC I think. If I were to buy a better quality stator do you think my cheap roter would be ok. I should have measured its diameter before installing it. (If anyone has one on the bench could you accurately measure the diameter in mm). How much do you reckon I should pay for one. Oh well! it's an Enfield. My other bike is a Triumph.

AgentX

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Re: Alternator probems
« Reply #10 on: February 06, 2015, 08:03:36 AM »
Alas, I'm not using that alternator anymore--I have an aftermarket two-wire resin encapsulated job, and the old one is either discarded or in storage in the States.  Sorry I can't assist.

High On Octane

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Re: Alternator probems
« Reply #11 on: February 06, 2015, 12:17:53 PM »
Alas, I'm not using that alternator anymore--I have an aftermarket two-wire resin encapsulated job, and the old one is either discarded or in storage in the States.  Sorry I can't assist.

Same here, I have to 2 wire 10amp Wassell replacement alternator.  It's stupid proof and works.  I did need to drill out my mounting holes a little bit to get enough adjustment, but that's it.  Just make sure that it is not rubbing the rotor anywhere, because it will burn up if it is.  Ask me how I know...   ::)

I think you may be able to use this one too, but not certain about that.  If so, it is Wassell part # 47205, and  is also the same alternator as a Triumph T120, so it may be possible to find it locally.  I've gotten my alternators locally from The Bonneville Shop, and they have an Ebay store as well.  Other members here have had good success ordering from them on Ebay as well.
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Kevin Mahoney

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Re: Alternator probems
« Reply #12 on: February 06, 2015, 05:27:50 PM »
Before you start buying new parts I think you should get to the bottom of it. I will talk about cheap parts in my next post.
If you are only getting 12.7 or so then either your stator, wiring or regulator are bad. First choice is stator but you really do need to check the other items out. Use a back-pin with a volt meter to see what is actually going into and coming out of your regulator. By that I mean using a paper clip, pin etc. to get your voltmeter into the back side of the connector so you can measure this real time. AC in DC out. If you have good AC going in (make sure you rev up the engine) and good DC (14 volts or more) going out then the wiring is the issue somewhere. Measure the AC at the stator and make sure you are measuring the correct wires. There should be two wires that are the same color and two that are different. The matching ones are a pair etc. Even a cheap alternator has a better than even chance that it might be working.

Kevin Mahoney

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Re: Alternator probems
« Reply #13 on: February 06, 2015, 05:48:56 PM »
Cheap parts
I do believe that you get what you pay for. Sometimes that means getting strong backup, replacement policy, warranty etc. often times it means a lesser quality. This is really true in RE parts. Because so many RE's have been sold over the years in India there is a very large and mature market for replacement parts. The bulk of the parts on the market are not genuine RE spares. Some look like it and many come in RE boxes and wrapping. I have seen this over the course of many years with my own eyes both here and in my extensive travels to India.
Customers in India are FAR more cost conscious than we are. Just a few Rupees can make a difference (62 Rupees to the $$ today) in whether or not a part will sell. The market for brakes, filter, gaskets and electrical parts are where much of the differences can be noted. For example none of the "just as good as" filters sold on EBay or from India are. Even sold in RE packaging one needs to compare them side by side. I have done this and speak from experience.
Alternators can be good or not so good. You can find some aftermarket ones that are encapsulated and some that are open. All of the OEM types are open. You will find a debate alive about the plusses or minuses of each. Quality is determined by quality and size of wire used, now many windings and accuracy of construction of the frame of the stator. Rotors can be judged by the material and build quality of the actual rotor but most importantly by the magnets. We see not only inferior magnets in some rotors but rotors that self destruct. This is usually caused by a magnet coming loose. When that happens the results are normally catastrophic.
Cheap alternators might work fine in many occasions. It is a bit harder on them in the US because we run with the headlight on all of the time which gives it more of a work out. You have a 50/50 or slightly better chance of doing fine with a cheap alternator.
If you buy a good alternator you are much less likely to have trouble. Does it happen? Of course but hopefully you have purchased from a reputable source and they take care of you. The difference in price versus the work etc. you go through trying to replace it etc. rarely work out.