Yes, its actually in my favorites list. I just want to know what my alternator is supposed to be putting out at any given rpm. I think the stator (and at this point the rotor, which is most unfortunate because it's balanced with my crank) is the culprit.
It's also raining cats and dogs right now, so I can't do much of anything. Bike will have to stay under cover for the time being.

Well, the best way to quickly test the "whole mess" is to go ahead and test the whole mess. I mean, why screw around with 100 individual component tests, fingers stuck in holes, wire inspection, etc, etc, when you can get right to the heart of the matter?

Take out the system fuse and replace with a 0-10A DC ammeter. (Turn ON the lights and the meter should go in a negative direction.) Crank the bike, turn ON the lights (high beam, please), and run her up to about 3000 RPM. The reading should be a positive 2A or so. You want it above 1A, but really not more than 3A.

The definition of "charging" is "positive current flow to the battery". If you have 1.5A or more of positive current flow then everything is fine.

Suppose it comes up to zero or 1/2A, but can't go higher. We'll it's charging, but the lights are using too much power for the alternator to compensate. So get a lower wattage HL bulb. 45W is usually the max for most riders.

And that's how you do it. Give us the numbers with HL ON and HL OFF at 3000 RPM. Nothing else matter much.

<Is there a definitive test for the stator?>
It's in your Triumph manual Sisyphus along the lines of 'at least 8.5v AC into 1 ohm at 3000rpm' (this is for single phase I don't know what the three phase manual says. Perhaps someone could help?)

The above was the original reason I started measuring output without a load ie what will it measure with just the probe leads stuck in the alternator leads. But as you have found ignition interference can be a problem (by the way this test works ok on my running Japanese bike).

I like that link Dave Jones, more comprehensive than the usual write-up. I especially like his way of testing zener diodes (shame to wreck two 9v batteries though <s>)

The writer is also correct in testing stators in that they either work or don't work being basically just a length of wire. But as we all know with Triumphs a length of wire can break or short to earth.

The one fly-in-the-ointment with Lucas alternators is the permanent magnet rotor. I have compared old vs new rotors on my rig and the difference in alternator output was not huge (about 10%). I now have a collection of rotors so will see if I can come up with a rotor test we can all do at home for comparison.

The one killer of rotors is a duff rectifier. This will allow battery current to flow through the stator and demagnetise the rotor. I suspect that this is rare though as this requires the diodes to fail short-circuit (and so allow current to flow.) My experience in electronics is that diodes usually fail open-circuit so no current would flow.

Derry.

That's great, Mr W. Rain has abated for the moment. Will test this morning.

W. Rain? Small world - I know his French cousin m. Effin Rain...

Perhaps it's simply time to turn to Creedence Clearwater Revival:

''Long as I remember, the rain been comin' down,

''Clouds of myst'ry pourin', confusion on the ground,

''Good men through the ages, tryin' to find the sun,

''And I wonder, still I wonder, who'll stop the rain.''

The Rain in June won't stop soon

Okay, song time is over. Lately I've had some song in my head where the words go, "Why you gotta be so mean to me...?"
Anyway, I went for the first of two test rides. I live in a pretty hilly area, unfortunately for me sometimes, because I can't push my bike up a hill, even the slightest, due to previous injuries to my shoulders and arms, lower back, etc. So I set off, made it about 3/4 mile with the headlamp off and the bike started running poorly, with ignition failures, stuttering, popping.
thinking I was about to lose all power I turned round and headed for the barn. Quickly. I got home and checked my voltage, 13.0. Okay, so what's the big deal? I started doing continuity checks with the Boyer and found this:


The other lead is connected to the B/Y wire. The B/W wire and it's respective coil show no resistance.

This may be (and probably is) a new problem.

But I need to go get a 1 Ohm resistor to check my stator.
I Know the cumulative ersistance in the Boyer plate should read 137 and min e does, but does this thing I discovered a "non-discovery" or is it a new, legitimate, problem?
thanks everyone for bearing with me and my problems. I think as soon as I get this sorted out I'm going to sell. This is really too much.

Sys,

You've got your meter on the diode test range - move it one click anti-clockwise and have another look.

Blapper

Alright, 66.5 then. Why is there resistance in one part of the plate and not on the other half?

Before you condemn your Boyer, or even spend much time checking it, are you sure it's getting its proper voltage? They're really sensitive to voltage. Try connecting a jumper wire from the battery - to the white wire on the Boyer box and running the bike. If it runs well, you have a simple wiring problem: ignition switch, kill switch, frayed wire or loose connector. The kill switch on my 1971 T120 failed on a ride last year, and I had to ride home with my rear, brake light switch hot wire plugged into my Boyer box, I now carry a jumper wire in my tool roll.

The first dozen posts or so.

Yes I read all those, but they all relate to charging system and battery voltage, which seem to be ok, if you're now heading towards Boyer diagnosis. My point is what voltage is the Boyer box getting? It's fed through a fuse, 4 feet of wire, a connector, more wire, connectors, switches etc., so you can't assume it's getting battery voltage, and judging by the "stuttering, popping" you describe, it's not. A jumper wire is the simplest way to ensure your Boyer box is getting battery voltage, whatever that may be.

I don't have reason to suspect that the Boyer isn't getting proper voltage based on the logic that up until this point I haven't had that as an issue.
However, now that you mention it, and given the uncanny history of successive, unrelated failures on this machine since I bought it years ago, it is a valid point. Even though it has all new wiring I have found one wire that was corroded in the middle of the run and it gave me endless grief because I wasn't willing to accept that there could be something wrong with a new component.
But if we can suspend that point for a moment--and I will check that lead--why is one coil on the Boyer plate showing resistance while the other isn't, even though together they show the proper value of 137 Ohms?

I haven't held a Boyer plate in my hands for a couple of months, so I don't know if it's easy or even possible to measure the individual coil resistance with it still mounted, isn't the circuit is printed on the back? If the combined resistance is within specification, I'd go to the next step. The chances of one coil gaining impedence equal to that lost by the other and the overall impedence remaining the same are pretty slim.

I just remembered an old mechanics joke, told to customers:

Q: What did the farmer say when his cow died?

A: It never did that before.

If you look at the photo you can barely see the soldered connection for the coil in the slots in the plastic thingy over it. You have to have a pretty pointy probe to get in there, but put one probe there and the other one on the wire and you should have zero resistance. It's highly unusual. I went through a spate of problems only last month and had to do this, and I didn't get a reading like that.

Sisyphus:
What are you doing with your meter's probe? One slight slip and you will render the plate useless. The coil's wire attached to the post you are reading is very fine (about .002" and soft as baby poop)... Touch it and it will break straight away. Place the meter probes across the the black/yellow and black/yellow connection terminals. Or, if the plate is off the bike, the solder points on the back of the phenolic plate.

The most common reason a battery will prematurely die is if it is left in a constant state of discharge (less than 12.6 volts). This could happen before you purchase the battery, sitting on the dealer's shelf. The battery will tolerate short periods of discharge if it is routinely brought back up to a full charge (12.6 volts). This will happen when the motorcycle's charging system fails to provide a charging current, as described by RF above and read with an ammeter.

To provide the proper charge the bike must be operated at an rpm that will maintain the battery at 12.6 volts with the load that is typically used (lights on, etc.). If the bike must be run at 3,000 rpm to maintain the battery at a full charge, running it at a lower rpm will eventually, sooner than later, kill the battery. Think about your charging system the next time you want to lower the engine rpm by putting on a 21 or 22 tooth sprocket.

If your battery was already in a low voltage condition, and had an internal defect or sulphated so the chemical action necessary for the battery to be a battery, coasting with the motor running at 1,000 rpm with the existing load, lights, etc., could have drawn the few remaining electrons out of the battery so it was unable to do any work. The bike was then running directly off the alternator, which itself was not turning at a speed fast enough to produce enough electrons to maintain the bike's operation properly.

Take a 20 to 30 watt bulb (this mimicks the load the Boyer and the coils put on the circuit) and rig it so you can put its terminals directly across the battery. Notice how bright the bulb glows. Now take one of the bulb's terminal leads and place it on the wiring harness feed wire where it attaches to the Boyer (negative ground Boyer = white wire). The bulb should glow as brightly as it did across the battery. If it doesn't you have a high resistance switch, or connection between the battery and the Boyer. Then take the same lead and put it on the red wire (ground). The bulb should not light at all. If it does you have a bad ground.

Load test the alternator using a 1 ohm resistor. If you don't have one, they are cheap and available through several sources or Paul Ackerman in Tenants Harbor (who also has the technical ability and equipment to test your electrical system).
John

John, RF you are both partly right.

RF I know you like your current flow and there is nothing wrong with that but you can have 2A current flow at 12v and still end up with a flat battery. As you know batteries are chemical devices and have certain requirements, one is the correct voltage.

Which brings me to John. Where does 12.6V come from for running your system? That is the nominal charged voltage of a 12V battery but running your system at 12.6V you will end up with a flat battery. To charge, and maintain, a 12V battery requires more than 12.6V.

A web site that I use for reference is http://www.batteryfaq.org/. Look at section 9 for charging algorithms.

I hope this helps.

Derry.

Yes, you need more than 13 volts to charge the battery and maintain it at a fully charged condition of 12.66 volts.

The question at hand is a response to: "Oh, this battery is a year old, sealed unit." I have a new battery why/how did it fail?

My point is, or was, if you do ride the motorcycle in such a manner as to not keep the battery fully charged, or 12.66 volts, it will die, dead...

You would be more helpful in these situations if you gave complete answers yourself! It is obvious that you have more than a mechanics understanding of these problems. It would save the rest of us a lot of time, albeit it might deny you the opportunity to show us how smart you are after the fact.
John Healy

Thanks again John.
Part of my problem is the wiring; though I rewired it this past winter, I must have gotten a bad batch of wire. I've already found corrosion in the middle of runs of wire, far from any connections.
I also may have damaged the stator when fitting the primary cover onto the two forward mounting studs after replacing my drive sprocket last week. It's always been an awkward fit and if I moved the studs aft at all to line up the cover, the clearance on the rotor would be insufficient. The results would be predictable.
I've borrowed Paul Ackerman's test box in the past. I think if I can get down there when monsoon season ends here I should see what the magic box can tell me.
Otherwise, since I live and commute through rural areas I operate the bike at highway speeds about 90% of the time. I've had the current setup for about a year now and haven't had any previous charging problems with it.