2022 vintage motorcars build.
So my battery was cooking and my alternator was overcharging.
Pulled the regulator out and one of the brushes broke. put a new
regulator in and its is still overcharging.
Something else is wacky. The alternator light was on. I started the car with the power line off the alternator and the alternator light got bright then poof, went out.
Wondering if my alternator is bad? Now its not charging at all.
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@Superuber posted:2022 vintage motorcars build.
So my battery was cooking and my alternator was overcharging.
Pulled the regulator out and one of the brushes broke. put a new
regulator in and its is still overcharging.
Something else is wacky. The alternator light was on. I started the car with the power line off the alternator and the alternator light got bright then poof, went out.
Wondering if my alternator is bad? Now its not charging at all.
Can you post a photo of your alternator? VW alternators don’t usually have an external regulator or “brushes”. Generators do, alternators don’t. The difference is important in defining a fix.
On the highlighted part above, I suspect that the dash alternator light is burned out and THAT will cause the alternator to not charge. Replace the dash bulb first and make sure the alternator battery wire (usually a 10 gauge wire) is attached before you do any testing. After that, If you swapped in a new regulator could you post a photo? We’ll go from there once we see what’s in there. It’s hard to diagnose when you can’t see what you’re working with.
... also start shopping for a new alternator, as these have their regulator built in. and don't confuse the alternator idiot light with any of the instrument illumination lights. Doing so can lead to some very weird shyt -- ask me how I know.
Just so you know for next time, the small wire (D+) on the alternator goes to the dash bulb, which supplies the alternator dynamo with an "eddy current" that starts the electromagnetic process that makes the alternator charge the battery. It also provides a signal to the alternator of how much the battery is charged. If that bulb burns out or is missing, the alternator will not charge the battery.
If the main battery cable on the alternator (the big one) is removed and the alternator is spinning, a helluva lot of voltage can be directed to that small bulb wire and burn out the bulb, thereby stopping the charging cycle.
So.... Never remove the big battery cable when testing the charging voltage of the alternator. It is relying on the battery to accept the voltage it is producing. Generally, a good charging voltage is in the 14 - 14.5 volt range which will decrease as the battery reaches full charge. This can (and often is) lower at idle, like down into the low-mid 13 volt range. If yours was producing higher than that, all sorts of nasty things can happen.
OK, thanks for that. I did see the bulb go. Do you think the wire got damaged?
Is there a fuse link?
(go easy-I'm a newbie to these) 
There is no fuse link on that wire - there is a fuse on the other side of the bulb in the Tach and that is probably the "ignition" fuse. I doubt that the bulb wire got damaged because, in a way, the bulb blowing acted like a fuse and protected the rest of the circuit. You could always test the wire end-to-end with an ohm-meter to be sure, if you're worried, but it should be OK.
OK, so the alternator bulb is wired a bit differently than you would expect.
There is a wire that goes from the fuse panel "Ignition" fuse right to one side of the bulb so it is energized when the key is "on" and lights up. The bulb base is insulated from ground and from the gauge. It gets its "ground" from that D+ wire (the small one) on top of the alternator. When the alternator is not spinning (engine stopped and key is "on"), the D+ acts like a ground to the bulb and the bulb lights up. OK so far....
As the alternator begins to spin and the electromagnetic process starts to charge, it looks to the D+ wire for a signal of what the battery voltage is, if you will, to start charging. Once it spins above a few hundred engine rpms, it starts generating a higher voltage than the battery resting voltage and sends some of that higher voltage (at a very low current) out of the D+ terminal to the dash bulb. The bulb no longer sees "ground" on that side.
So the D+ has gone from being "ground" to making 12 volts or higher. Sounds like magic, I know, but lots of physics seems like magic, especially electro-magnetism (and don't get me started on Quantum physics - That $#!+ is spooky). So now you have +12 volts on both sides of the bulb, they both cancel out and the bulb does not light. Pretty cool, huh?
Long winded explanation, but you could check your fuses for a blown one and replace it if necessary. If the engine starts, then chances are the fuses are OK. Same thing with the bulb - Check it and replace it with a new one. Remember, the alternator will not charge if the bulb is burned out or missing.
And what might be the first name of Mr. Superuber??
Rick is my name.
Thanks, I'll keep you posted.
You Sir are a wealth of knowledge....
Hi, Rick.
Yup, much like Calvin in Calvin and Hobbs, I have a brain full of useless information.
Update: Just put on the alternator. It's charging 14.1 now. Alternator light key on. off running.
Again thanks Gordon. BTW- I replaced the bulb before I started it.
👍👍
Well done, Rick!
Now get it out there and drive it!
And don't forget to visit a bunch of us at the Carlisle, PA show grounds next May for our annual Carlisle gathering. Check "Events" later this year for a planning update.
Also, you may be interested in the "Tour de Smo", this year in Virginia/West Virginia - Check events. More of a driving event than a show field, for sure, and a great bunch of replicas of several types. You get to meet a bunch of people who post on here, including the President-for-Life of Stanistan and, this year, the Butcher-to-the-stars from Silicon Valley.
We're a very eclectic bunch, fer sure....
LOL. Yeah I'll be at Carlisle in May.
I'm 20 minutes from the fairgrounds.
I do have a few questions for the group:
I ended up getting just a cheapo alternaot because Amazon was cheap and fast.
What is the best source for an alternator?
Also I own a 22 VMC build. 1500k miles. Do you think this is premature
to be doing the alternator? I am running an amp and a sub from the
radio that VMC installed.
I guess it all depends on where both of the alternators came from. There are a LOT of cheap, Asian replacement parts out there and they may not be the highest quality by a long shot. The real German ones are the best, but they can be eye-poppingly expensive. Last one I bought was a Bosch AL82 60 amp rebuilt and it has been doing fine for over 20 years.
Do a search for "bosch al 82 alternator" < that's a link on Google - You should get a bunch of hits but make sure you're buying an original Bosch AL82.
