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Mon Aug 17, 2009 11:09 am

What would cause an alternator to overcharge? My 64 Bug is converted to 12V and at ilde it reads 18v. I called an auto elect shop and the guy said something about full fielding, he went on to say something in my wiring may be causing to alternator to overcharge? How's that? My VW wiring oh which was designed to handle 6 volts is now causing an alternator to overcharge at 18 + volts. I asked him about the internal VR and he just kind of brushed that off. A rippoff.

Mon Aug 17, 2009 11:37 am

Bad voltage regulator. Your mechanic is used to modern alternators where the regulator is built into the alternator. Your regulator is under the back seat on the driver's side. Suggest you get a new one at once before you cook your battery.

Mon Aug 17, 2009 11:52 am

Rusty O'Toole wrote: Bad voltage regulator. Your mechanic is used to modern alternators where the regulator is built into the alternator. Your regulator is under the back seat on the driver's side. Suggest you get a new one at once before you cook your battery.

Rusty, that voltage regulator under the back seat is for a generator, not alternator. Most alternators have an internal regulator, or one that mounts to the alternator itself.

Mon Aug 17, 2009 11:55 am

No, it's not. We've been discussing it in another thread. This does have an internally regulated Bosch alternator.

And it's not the vehicle wiring, unless for some reason alternator output is not connecting to the battery, but it would be dying if that was the case.

I asked in that other thread about making sure you really do have 18V both at the alternator and at the battery - does it?

Be careful around the battery if it really is getting that much voltage, you'll have fumes coming off of it, explosive ones. They'll melt the hairs in your nose too! As I mentioned before, might want to see how the water level in the battery is doing.

-Andy

Mon Aug 17, 2009 11:57 am

Rusty, on a stock later Bug the 12 volt regulator is under the seat on the drivers side but not on mine. That would be too easy considering the PITA it is to pull the alternator. A 64 had the 6 volt regulator sitting on top of the generator. My Bug was converted to 12V by a previous owner. Its running a Bosch AL82N with an internal voltage regulator. I'm getting alot of very different opinions from the VW community. Some say replace the alternator with a "new" (see note) one. Some say I can just have the internal VR repaired but one guy in Southern Cal is asking $425. for a VR! I would like to find a genuine Bosch but I'm hearing good luck on that. I am not interested in any part made in China, so where or who has a decent part?
PS my battery was at 16volts, it had fluid in it and its sitting on my bench.
That's one thing I may have got lucky at.

note: Made in China with a Bosch sticker on it. Made in Brazil, made in Japan, made in some guy's garage in Covina who tells you its new when it has 200,000 miles on it. But not made in Germany anymore?

Mon Aug 17, 2009 12:12 pm

Actually, I thought the AL82N was Brazillian. And is now out of production, so chinese clones are now the only option once current stock runs out.

German production on bug alternators ended a long time ago.

Mon Aug 17, 2009 12:15 pm

i just had this problem ,.. i blew a few bulbs , one headlight , and fucked up my pertronix !!!.. don't start it untill you get ti fixed ,.. all you need to do is replace the volt regulator , there about 40-60 bucks , and you can do it yourself , i had the regulator inside my alternator.

good luck.

Mon Aug 17, 2009 12:46 pm

rm56 wrote: What would cause an alternator to overcharge? My 64 Bug is converted to 12V and at ilde it reads 18v. I called an auto elect shop and the guy said something about full fielding, he went on to say something in my wiring may be causing to alternator to overcharge? How's that? My VW wiring oh which was designed to handle 6 volts is now causing an alternator to overcharge at 18 + volts. I asked him about the internal VR and he just kind of brushed that off. A rippoff.

We already told you all this in your other thread!

Is that the only alt/auto electric shop in town?

Tons of choices in the classifieds...

http://www.thesamba.com/vw/classifieds/search.php?...ton=Search

Some people take the chances at the local auto store chains too.

Like Andy said, last of the Genuine Bosch were Brazil and Mexico but they ended production and let the Chinese ( or anyone? ) I guess have the rights to tool up for stuff they decided not profitable enough to make any longer.

I have seen some Chinese ones last okay and others fail in short order. It's the "crap shoot" nature of quality control with many parts/products not only for these cars but many things in life. :roll:

If you don't want alternator you can always go back to a 12 V generator and external voltage regualtor too.

You have plenty of choices... the same all of us have to deal with.

Tue Aug 18, 2009 8:01 am

Thanks for the advice. Last night I was able to get the 36mm nut on my fan loose with the alternator in the car. That should make swapping out easier when I get the new alternator. I'm going to lift the shroud and see if I can get the fan out attached to the alt without pulling my intake. In three weeks is the local Bugorama, would that be a good place to pick up an alternator for less? Thanks

Tue Aug 18, 2009 11:18 am

If my 64 Bug is missing the ground strap from the transaxle nose to the car or if the battery ground is corroded could that cause an alternator to overcharge up to 18 volts due to improper grounding? Thanks

Tue Aug 18, 2009 12:08 pm

IMHO doubtful... but I won't swear to it! :lol: :wink:

Tue Aug 18, 2009 1:29 pm

He still needs a new regulator.

Possibly your best shot is an independent auto electric shop if you can find one that won't rip you off.

Example. I went thru something similar recently with a Lincoln Town Car. They use the same motor as a Ford but the alternator is bigger. A Ford alternator cost $75, a Lincoln costs $330 for new or $285 for rebuilt. The local small town auto electric shop quoted me $185 for rebuilt. In the end the bill was only $45 because all it needed was a new regulator and a set of brushes.

The point is if you take it to a good repairman he can fix it pretty reasonably. Also, there are 3 or 4 different grades of quality in the parts they get even if they all come from China. A good man will use good parts even if they cost a couple of bucks more. The cheap chain store alternators always use the cheapest parts, that's why they are so short lived.

How you find a good honest auto electric shop is another question.

Tue Aug 18, 2009 1:32 pm

rm56 wrote: If my 64 Bug is missing the ground strap from the transaxle nose to the car or if the battery ground is corroded could that cause an alternator to overcharge up to 18 volts due to improper grounding? Thanks

A bad ground can blow an alternator. I didn't think it could until I saw it happen. One car went thru 4 or 5 alternators until I put on new ground wires and new wire to the battery.

Tue Aug 18, 2009 1:35 pm

rm56 wrote: Thanks for the advice. Last night I was able to get the 36mm nut on my fan loose with the alternator in the car. That should make swapping out easier when I get the new alternator. I'm going to lift the shroud and see if I can get the fan out attached to the alt without pulling my intake. In three weeks is the local Bugorama, would that be a good place to pick up an alternator for less? Thanks

With the fan nut loose you can take off the fan and leave it sitting in the shroud while you take off the alternator. I don't think you can get the alt out with the fan still attached unless the motor is out of the car.

Tue Aug 18, 2009 1:42 pm

"PS my battery was at 16volts, it had fluid in it and its sitting on my bench. "

Your voltmeter is reading high. The most you can get out of a brand new fully charged 12 volt battery is 13.2 volts.

Your alternator should be putting out 14.5 volts max.

If your meter is reading 3.5 volts high it would read 16 volts for 12.5 and 18 volts for 14.5.

In other words it could be there is nothing wrong with your car, you just have a real wacky volt meter.

See if you can get your hands on another meter and find out what's what'

Tue Aug 18, 2009 1:46 pm

By the way didn't the alternator equipped beetles of the 70s have external regulators under the seat?

Tue Aug 18, 2009 1:58 pm

You may be onto something with a possible bad VM. I'll double check the calibration on it. I set mine on the 20 volt scale. Its a digital one, but I have an old analog to I'll try that one. Yes the older bugs had the 6 volt regulator on top of a generator. The newer ones just like my service manual shows had a VR under the back seat on the drivers side. As I mentioned before a previous owner modified my 64 Bug to 12 volts using an alternator with an internal VR kit. Someone pulled out all the old parts, nothings remains of the old set up.

Tue Aug 18, 2009 2:12 pm

The reason his battery is showing 16V is because his alt has been putting out 18V and has it over charged... it is possible to make a battery take higher charge than it's rated for. He can hook it up to something and discharge it some and get it back down into the high 12 - 13 V range.

Yes the original alternators from 73-74 maybe mid 75 did have 'external' regulators but after that production switched to internal regulators. While stil possible to find some rebuilt external regulator "AL- 78" styles most of what is out there is the AL- 82 style / China clone with internal regulator.

This thread has a breakdown and pics of the different ones over the years.

http://www.thesamba.com/vw/forum/viewtopic.php?t=315341

Tue Aug 18, 2009 3:05 pm

I am going to double check my VM on several other vehicles I have just to be sure its reading correct. I will also check everything with my analog meter that I have. And I'll check my cables and take a look under the car at the ground that goes from the trans to the body. It will get done, just may take a bit. Just wish I could fix it before the big VW show here on Sep 5th. I missed the first one cause my engine was pulled, now this. Oh well maybe I'll go to look for parts :lol:

"He can hook it up to something and discharge it some and get it back down into the high 12 - 13 V range." How about my hand held bug zapper? Great fun! Here kitty kitty just kidding... :twisted:

Tue Aug 18, 2009 3:09 pm

rm56 wrote: I am going to double check my VM on several other vehicles I have just to be sure its reading correct. I will also check everything with my analog meter that I have. And I'll check my cables and take a look under the car at the ground that goes from the trans to the body. It will get done, just may take a bit. Just wish I could fix it before the big VW show here on Sep 5th. I missed the first one cause my engine was pulled, now this. Oh well maybe I'll go to look for parts :lol:

"He can hook it up to something and discharge it some and get it back down into the high 12 - 13 V range." How about my hand held bug zapper? Great fun! Here kitty kitty just kidding... :twisted:

When you check it with your VOM ( if your VOM reads correct on other car battery or battery charger etc) then just stick it back in the car and leave the headlights on for an hour or so and check it again.