Charging Light

[blackcat]

Grrrr.....no more 14.1. 

I may just throw in the towel and buy the EnDuralast system, though I really don’t want to spend $500 bucks on this bike. 

[nighthawk]

If the rotor resistance is lower than specified won't the output always be somewhat low? That guy from Cycle Electric wised me up to that once.

[wirespokes]

Most meters aren't very accurate in the range we're looking at here. If it reads generally in the ball park, that's about the best you can hope for.

What's it charging at now?

The test for the regulator is bypassing it. Pull the three terminal plug and jumper the two leads that aren't the ground. Start up the engine, slowly rev it and watch the meter. Once it gets to mid 14V, back off. The voltage will continue rising the higher the RPMs.

If it doesn't make it up past 14.0, then it's either the rotor, stator or diode board. The most common failure is the rotor. The windings can short together resulting in a weak magnetic field and less voltage generated. Rotors can pass a static test, but fail dynamically. Sometimes it's best to have a known good spare to swap.

[Chuck in Indiana]

Well, if you would just do what I tole ya and check AC voltage on the 3 yella wires.. you can tell whether the alternator is alternatin properly.  If it is, it's probably the diode board.

[blackcat]

Most meters aren't very accurate in the range we're looking at here. If it reads generally in the ball park, that's about the best you can hope for.

What's it charging at now?

The test for the regulator is bypassing it. Pull the three terminal plug and jumper the two leads that aren't the ground. Start up the engine, slowly rev it and watch the meter. Once it gets to mid 14V, back off. The voltage will continue rising the higher the RPMs.

If it doesn't make it up past 14.0, then it's either the rotor, stator or diode board. The most common failure is the rotor. The windings can short together resulting in a weak magnetic field and less voltage generated. Rotors can pass a static test, but fail dynamically. Sometimes it's best to have a known good spare to swap.

When I checked it yesterday, it was charging in the high 12’s, which is weird considering it was 14.1 when I installed the new rectifier.  I’m going to install a new battery tomorrow to make sure that isn’t an issue.  If that is not the problem, I’ll order a new rotor on Monday.

“Well, if you would just do what I tole ya and check AC voltage on the 3 yella wires.. you can tell whether the alternator is alternatin properly.  If it is, it's probably the diode board.”

It was easier to install the new rectifier than cranking the engine up to 4,000 rpm multiple times given my location. BUT, I will try that today and report back.

[wirespokes]

So you've replaced the diode board and regulator - problem persists. Could be the rotor - it is the most common failure after all.

The battery. I recall a charging thread on Adventure Rider in the airheads section that went on for ever. I want to say sixty or seventy pages. In the end it was the battery.

Some of the simplest things can cause the most trouble.

[blackcat]

So you've replaced the diode board and regulator - problem persists. Could be the rotor - it is the most common failure after all.

The battery. I recall a charging thread on Adventure Rider in the airheads section that went on for ever. I want to say sixty or seventy pages. In the end it was the battery.

Some of the simplest things can cause the most trouble.

I don’t think it is the battery because I’ve installed this new loaner battery once before with the same results, but that was before I made all these changes. Just want to rule it out before I order the rotor. 

[Old Jock]

I'm with Chuck on this

First thing that should be done before commencing any checks is charge the battery up let it sit for a couple of hours then measure the resting voltage it should be around 13.5 from memory, certainly above 13.

Voltage checks are meaningless if you don't know for sure the battery is completely charged as it will just pull the whole system down.

The way I do it, which is not to say it's the best, is check the alternator as mentioned by measurring open cicrcuit voltage. If it's not doing it's thing then full field flash it and try again.

Once that's all ruled out you can move onto the reg/rec

[John A]

Can’t you full field it with a 12v jumper to the DF+ while it is running to see what the max output is?
First you mite as well check the ac side like Chuck suggested

[blackcat]

Ok, charging to 13.20.

Battery is fully charged to 13.5

Pulled the plug to the voltage regulator and it’s about 12.

Did as Chuck recommended and I’m not anywhere close to 45VAC, but I could easily not be doing that right. I set the meter to AC colts and took the reading.

[Chuck in Indiana]

So what was it? They should be pretty equal between 1-2 1-3 2-3. I'm pretty sure the 45VAC is right at 4K, but haven't found it with a quick search. I'd think at least 40 volts. If it's very low, it's either the rotor (most common failure) or stator. No need spending money <snapping suspenders> unnecessarily.
I'll look for a source.
Edit:
Found this in my "Guzzi stuff" files..

1-2, 1-3, 2-3. At around 3-4k you should be seeing something like 30-40V AC but whatever the figure, it should be the same on all the phases.

Edit again:
Googling shows 40VAC to be a common number from an alternator.

[Old Jock]

Chuckie beat me to it, yeah I'd think at least 30 but more like 40 I've never seen a factory figure as they suggest you load check it (like really practical NOT!!)

All I have to add is

If that's not doing the business full field flash as described by John A and try again.

If either of these test are satisfactory the alternator is good.

If you had to field flash to get a reading then possibly the Voltage regulator isn't doing it's thing or the brushes or the connections for the excitation

All I got for now

[blackcat]

With my meter set to volts A/C:

1-2: 12.7
1-3: 12.9
2-3: 10.9

Tach cable broke so this is an assumption of 4K

[wirespokes]

The best test of a battery is a load test. You can get a load tester at Harbor Freight. I've been told they're good. But why buy one when you've got a good load right there on the bike? Watch the volt meter (hooked to the battery terminals) while cranking. It shouldn't drop below ten volts if I recall correctly.

I've never taken an AC reading off the alternator - I ought to just for the experience. And to know what to expect.

[Old Jock]

These are strange readings BC

Normally it works or it doesn't

Did you try to Full field it and test?

John

[blackcat]

These are strange readings BC

Normally it works or it doesn't

Did you try to Full field it and test?

John

John,  I maybe completely wrong as to my meter setting, but I put the dial on Volts and change it from DC to AC:



No, didn’t try testing it at Volts DC, but I will do that this morning.

WS, I’ll try the load test as you described, but I don’t think it is the battery.

[Chuck in Indiana]

You either have a bad meter or a bad alternator. <shrug> I'm betting on the alternator.

[blackcat]

You either have a bad meter or a bad alternator. <shrug> I'm betting on the alternator.

I’ll try another meter today.  Hmmm....MG Cycle no longer sells alternators, I’ll try cleaning it again and hunt for another source.

[Old Jock]

BC

No not DC Volts

The meter does look right to me, and it would apear that it Auto Ranges

When I said full field flashing that is jumping a 12VDC wire (perhaps from the battery) to the DF on the Alternator

If you then conduct the test again and nothing changes then it looks like your alternator is defective. Again you should be measuring AC Volts not DC. If you measure DC it will read next to nothing

That and what Chuck said

[Chuck in Indiana]

I’ll try another meter today.  Hmmm....MG Cycle no longer sells alternators, I’ll try cleaning it again and hunt for another source.

There's no need to spend money unnecessarily.  <snapping suspenders, chomping on corncob pipe.> It'll either be the rotor (most likely) or the stator. You've already checked the brushes, etc.

[kirby1923]

Had this problem on my CX a couple of years ago...it was the rotor and got a new one from MG.

This engine likes to eat rotors as being on the end of the crank has a tough life.

[wirespokes]

Had this problem on my CX a couple of years ago...it was the rotor and got a new one from MG.

This engine likes to eat rotors as being on the end of the crank has a tough life.

Hard acceleration and deceleration eventually works the windings loose, then it's downhill from there.

[wirespokes]

I'm curious if the meter was auto ranging and the reading is in KV?

I wonder why, when flashing the rotor, the engine should be running?

[blackcat]

Did the flash, went for a long ride, mostly local roads without too much stop and go with the headlight on and when I came back the battery was at 13.4.  When I get back home, will check it again then make up my mind about getting a new rotor.  This one is about 10-12 years old?

[Old Jock]

I'm curious if the meter was auto ranging and the reading is in KV?

I wonder why, when flashing the rotor, the engine should be running?

BC did say that he was getting around the 12 Volt mark AC on the phases, so I think the picture taken was with the meter at 0 Volts and that's just pic up/drift

What I was getting at was not to try remagnetize the field but to give the field max welly, that way the alternator is going to get plenty excitation, so BC would know for sure if the fault was with the Alternator

Just testing O/C voltage will not distinguish a fault in the Alternator from a faulty regulator which could be opening the excitation.

With an O/C test he also wont blow the bulbs or frry the battery which he could if it was connected up to the rest of the bike

So my reasoning is if the turny bit gets no straight electricity which means the magnet doesn't get magnety which means the stoppy bit can't make any squiggly electricity

[Chuck in Indiana]

Very nice technical description..

[pete mcgee]

After market alternators.
Have a read here
https://bmwmotorcycletech.info/AftrMrktAlt.htm

Yes hes a beemer rider, yes its applicable to guzzi in that these system will fit.
Interesting data on outputs.
Also on his web site is a very in depth trouble shooting guide.
Worth the read.
I used this web site and guzziology when trying to find out why my electron pump wasnt pumping even though EVERYTHING had continuity, the correct resistences, operating diodes and minimal wear on rotating contact surfaces, I have everything except an output voltage above battery voltage.
What fixed it?
In the end after cleaning every contact, replacing wires, cleaning stators, rectifiers, inventing new swear words, pulling hair etc the only thing left was run a oldering iron over all the solder joints on the stator.
The bloody thing worked after that.

[blackcat]

Yeah, that’s a keeper.

“So my reasoning is if the turny bit gets no straight electricity which means the magnet doesn't get magnety which means the stoppy bit can't make any squiggly electricity.”

I give up, just going to order a rotor and then a stator if that doesn’t work. 

https://bmwmotorcycletech.info/AftrMrktAlt.htm

Will read this over in case I missed something. Obviously I’m no electrical wizard, so if it’s all new parts and it works then so be it.

And I road the 60 miles home in stop and go NYC traffic, 12.4 with the headlights on as needed.

[n3303j]

It was standard practice to "flash" a generator to create a magnetic field in the iron bits. This residual magnetism was enough to start the generating process when the generator was spun up to proper RPM.

Never flashed an alternator as it is not necessary or beneficial. The alternator rotor is supplied an initial current fed through and limited by the dash charge indicator lamp. This current supplied is enough to induce a magnetic field at the rotor. The magnetic field passing through the field windings (stator) causes them to put out a current flow. At this point the regulator takes over and supplies current to the rotor at a level to produce the desired output from the field.

That's why it takes extra RPM to put out the idiot light on initial startup (because the idiot light doesn't pass much current). Subsequent excitation is supplied by the system output which has a much higher potential.

[John A]

When you apply 12v to the field ,marked DF+,you are bypassing the regulator and she puts out everything it can find. You prolly have a semi retired rotor. Just a guess mind you. Could be the smoke leaked out as well.