Charging woes

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appetite
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Charging woes

Post by appetite » Mon Aug 28, 2017 3:57 pm

Kind forum,

Looking for insight and possible solutions on a charging issue in a 69 bus with a 71 dual port engine, alternator conversion.

VDO voltmeter had been showing an erratic charge for a while, under 12 volts at times. But it would spring up to 14 volts.

Past two weeks, charging had become more erratic. One evening, there was a noticeable drain, dimming lights and gauge readings in the single digits.

This morning, the battery was dead.

Another consideration: idiot light does not always light on start up. Sometimes, but not always.

Sooooo...

Alternator? Is there a chance that the internal voltage regulator is kaput? Is there a way to test?

Thanks,

James

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vistacruzer
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Re: Charging woes

Post by vistacruzer » Tue Aug 29, 2017 9:25 am

charge battery, clip a wire on the hot terminal on the alternator. Clip the other end to the spade connector on the alternator. drive the bus and monitor the voltage if it is not steady and you have good battery connections and battery ground it is most likely your alternator. check the transmission ground strap.
do the battery and ground strap first.
71 bench 1915
70 wide lowered body rag top 2056 type4 DTM nothing stock if I could touch it.
Growing old is mandatory. Growing up is optional.

bus71
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Re: Charging woes

Post by bus71 » Tue Aug 29, 2017 9:55 am

I had similar problems recently. Check connections first. In my bus (71) the slip rings on the armature were worn. It's a challenge but you can remove the brush holder on top of alternator and peek in with a mirror. Some alternators also have the regulator attached there also.( Motorola?) When you look in you will see two copper rings inside. Clean them with eraser on a pencil. On mine I had bought brushes but the rings we're so worn it didn't help.
PS. The charge light must be working and have good contact for the alternator to charge.
Good luck!

appetite
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Re: Charging woes

Post by appetite » Tue Aug 29, 2017 5:06 pm

Thanks. I will report back.

appetite
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Re: Charging woes

Post by appetite » Mon Sep 04, 2017 9:29 am

OK, so I checked all the connections. I cleaned the posts on the battery (they needed it) and made sure all the grounds had good contact. I replaced the positive battery cable because it was pretty gnarly.

I charged the battery and got the bus started. The VDO voltmeter continues to vacillate, but sometimes it shows the alternator charging.

See:

https://www.youtube.com/watch?v=BQPPV4Sk0mk

and

https://www.youtube.com/watch?v=BVHtc1cpfUg

So, some dumb questions:

How does the internal regulator on the alternator work? Does it "know" when to charge, based on the draw from electrical usage and the strength of the battery?

So sometimes, the voltmeter will read less than 12 volts and at other times, read a steady 13+? Or should the alternator always be pushing a steady 13+?

Finally, does the Gen light sense alternator output? If so, is it possible that if the battery is fully charged, the Gen light won't come on at start-up?

Thanks for any insight.

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Amskeptic
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Re: Charging woes

Post by Amskeptic » Mon Sep 04, 2017 9:40 am

appetite wrote:
Mon Sep 04, 2017 9:29 am

So sometimes, the voltmeter will read less than 12 volts and at other times, read a steady 13+? Or should the alternator always be pushing a steady 13+?

Finally, does the Gen light sense alternator output? If so, is it possible that if the battery is fully charged, the Gen light won't come on at start-up?

Thanks for any insight.
When the engine is off, the generator warning light is provided 12 volts from your ignition switch and grounded through the alternator brushes.

When the engine is running, the ignition switch is still providing 12 volts, but now so is the alternator back at it. That shuts off the warning light because 12 volts on both sides means no current/no lamp illumination.

I think your alternator brushes may be worn out and are intermittently losing contact.
Colin
(but your old clutch plate is fabulous)
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

appetite
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Re: Charging woes

Post by appetite » Mon Sep 04, 2017 4:10 pm

So is the remedy a new alternator? Can the brushes be swapped out?

I dread having to get at that nut behind the fan shroud to remove the alternator.

James

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asiab3
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Re: Charging woes

Post by asiab3 » Mon Sep 04, 2017 5:43 pm

There are some pictures here of removing the brushes with the alternator in a bug. If yours is the same style, it should be easy enough to visibly check the brushes and slip rings.

http://www.vw-resource.com/alternator_r ... html#brush

Good luck,
Robbie
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

appetite
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Re: Charging woes

Post by appetite » Tue Sep 05, 2017 7:14 am

Mine is not a Motorola, but I will see if I can pull the brushes out in the same way.

Thanks everyone for the info. I will dutifully report back.

James

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Amskeptic
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Re: Charging woes

Post by Amskeptic » Thu Sep 07, 2017 4:29 pm

appetite wrote:
Tue Sep 05, 2017 7:14 am
Mine is not a Motorola, but I will see if I can pull the brushes out in the same way.

Thanks everyone for the info. I will dutifully report back.

James
Is it a Bosch?
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

appetite
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Re: Charging woes

Post by appetite » Thu Sep 07, 2017 7:16 pm

Yes, it is a Bosch AL82N according to the sticker.

It looks like this one:

http://volks-shop.com/media/catalog/pro ... _al82n.jpg

It has been pissing rain, but I hope to get to the task tomorrow. I'm hoping the brushes and the slip rings are accessible under that black cover that holds the spade connector.

James

bus71
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Re: Charging woes

Post by bus71 » Thu Sep 07, 2017 8:07 pm

The brushes are under that black plate. They are attached to it. You need to lift it up about 3 inches to remove it. You will Also see a flat finger that connects to holder to provide contact. These can lose tension over time. I clean the slip rings with an eraser while slowly turning alternator (belt off). The rings can wear and look blue/ burned and even develop a taper. If the slip rings are shot, it's rebuild time or new alternator. It may help to remove carb and loosen clamp/strap for elbow room. It really is a bit of pain because you working by mirror in a bus. If you need a new alternator, I'd be tempted to pull the engine and do some other maintenance at the same time. Hope this helps!

kreemoweet
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Re: Charging woes

Post by kreemoweet » Thu Sep 07, 2017 9:11 pm

In order to remove the brush holder to inspect the brushes on an AL82, you'll have to disconnect a couple of spade connectors on the brush
holder, one 1/4 in and one smaller 3/16 in. The brush holder body almost touches the slip rings, so if there's any brush length left protruding
with some spring tension, they're probably OK. New brushes protrude from the holder about 10-11 mm. Once the brush holder is removed, you
can look down in the hole and see if the slip rings are all gnarly or not.

That said, you really should not be using an aftermarket VDO volt gauge to diagnose or troubleshoot an electrical problem. They are just not
reliable or accurate enough. Sticking gauge needles are a fairly common thing. An actual electrical test instrument, i.e. a multimeter of some sort,
is a very useful thing to have.

appetite
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Re: Charging woes

Post by appetite » Sat Sep 09, 2017 11:57 am

Hi all,

OK, I think we may have found the solution.

I disconnected the battery, removed wires and got the black plate off. I struggled a bit with the spade connectors, but I didn't need to remove the carb. I mounted a mirror on the fan shroud and stuck a light in the engine compartment. I followed the procedure as described, using an eraser to clean off any grime on the brushes and slip rings. It was pretty dirty inside the alternator, oily and grimy. The slip rings weren't awfully dirty, but did have some sticky black soot in places. I went through the cleaning procedure a few times, spinning the pulley to make sure I got all of the surface area of the rings.

Hooked everything back up, started the bus up and hooray, the VDO is showing 13+ volts. I realize that the gauge is not the most accurate; I use it only to recognize trends in the charging system. I brought the bus over to a nearby mechanic to borrow his voltmeter. Same reading: 13.4. So perhaps this has solved the issue.

A couple of caveats...

First, I don't know how much of the brushes are supposed to be left. There's still another inch and action in the springs. See here:

https://www.youtube.com/watch?v=0QA4Nb7SKJI

Second, the slip rings don't look totally brass. They look more silver. It's hard to see, but take a look:

https://www.flickr.com/photos/23704155@ ... ed-public/

https://www.flickr.com/photos/23704155@ ... ed-public/

Perhaps they are wearing?

Many thanks to the collective wisdom and insight of the forum. I could not have diagnosed the problem without your ideas.

James

kreemoweet
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Re: Charging woes

Post by kreemoweet » Sat Sep 09, 2017 7:54 pm

Your brushes look fine. Can't tell much from your slip ring pics. The slip rings are thin copper (about 1.5 mm), and when clean and smooth
look unmistakeably like shiny copper. They can get grooved and pitted with age, and brush carbon (and in your case apparently oily grunge)
gets in the grooves/pits and makes em look gray or blackish. I don't know about "silver": personally, I would continue the cleaning process
until I saw something that looked like clean copper.

Rebuild parts for the AL82 are (or were) available: bearings, slip rings, regulators, brush holders, and combination regulator/brush-holders. But then,
brand-new Bosch AL82's are available fairly cheaply ($170.?) at amazon.com and I suppose ebay too.

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