Aftermarket Regulator Issue

[Matthew Devereux]

I've got an aftermarket 12 volt regulator that has never worked (I replaced it with an electronic regulator which works very well) and I would like to try and get it operational on my engine test stand. My knowledge of regulator operation is slim. The battery voltage doesn't change when I rev the engine. There is no voltage at the FLD and ARM terminals (engine not running). I pulled the cover off and see that the middle contact (ARM) is open. Is it supposed to be normally closed and open up with the bobbin pulls down?

[WilliamVaughan]

"There is no voltage at the FLD and ARM terminals (engine not running)."
That is as it should be. With the engine not running the disconnect relay disconnects the generator from the battery to prevent reverse current flow from the battery through the generator armature and field winding. I am guessing the disconnect relay is at right in the photo. It monitors both the armature voltage and the armature output current.

I see the heavy wire for the armature output current wrapped around the middle relay.
I am guessing that the middle relay is the armature current monitoring relay.

"Is it supposed to be normally closed and open up with the bobbin pulls down?"
That is what I would expect it to do. I would expect the voltage regulation relay (left) and current limiting relay (middle) to have their contacts wired in series so as to both be able to connect or disconnect the generator field winding terminal (DF) to ground.

Since the unit looks brand new it is odd that current limiting relay is not set up properly.

[Don Gale]

Does it need to be "polarized"?

http://www.vw-resource.com/alternator_g ... html#polar

[WilliamVaughan]

"Does it need to be "polarized"?"
This "issue" probably has more to do with the design of the current sensing relay.

How can the manufacturer copy so many aspects of the three relay regulator and get this part so wrong?
The current limit is certainly set to a value that is safe for the generator. It is set to zero. Can't get any safer than that.

You would need some electrical test equipment to experiment with setting current limit.
This "issue" leads to concern that there may be other hidden problems with this regulator product.

[Matthew Devereux]

Thanks for the replies. I believe your assumptions are correct Robert. Its just on the test stand so I may have a go at adjusting the center relay. I don't think I can do much harm? I can just leave the charger on the battery or buy a Bosch electronic relay for $40 too.

[Al Zim]

We were never able to get a voltage regulator for cars made in the USA to function with a 356 generator 6 or 12 volts. Lots of money spent with a trash can full of regulators the left the building forever. It is important for you to note that if you are using the 90MM generator it's maximum output is 22 amps. a 30 amp regulator will cause the generator to overcharge and try to disintegrate. Using the 12volt larger VW generator is an excellent solution except you cannot find any generator pedestals. If you do find one then for a single grille deck lid car you will have to shorten the oil filler. When Zim's rebuilds a generator, we always replace the field winding and the armature. It has been two years since we have been able to purchase any armatures. If you are changing to 12 volts remember to change your starter the 6 volt starter will grind the teeth off the flywheel even if you put a 12 volt solenoid on the starter. Gauges, relays and motors all need voltage reducers to operate on 6 volts. al zim 2019/04/21

[Paul Lima]

I drew this pix a long time ago to better understand how the VR works. Maybe it would help.

Generator-Voltage Regulator.pdf

(15.39 KiB) Downloaded 81 times

[Geoff Fleming]

Al,
You are wrong on the issue of the 12v solenoid used with a 6v starter motor when installed in a 12v car. You will NOT grind the teeth off the flywheel, since the solenoid allows for a smooth engagement.
I speak from a standpoint of one who knows from reality. I used my factory 12v 356 as a daily driver for a dozen years and once I incorporated the 12v solenoid, ( previous owner simply used a 6v starter, which did cause the teeth to be damaged.), the starting was wonderful. This car was used 365 days per year, so weather played no part.
I also know of others who have done this simple switch and never have any grinding issues. The other advice is fine but not the advice concerning the starter/ solenoid issue.

[Paul Lima]

The only person that I know of who tried the 12v solenoid on a 6v starter when he converted his 64C to 12v successfully ground off all the ring gear teeth within a year.

[Al Zim]

I do not believe there is such a thing as a smooth engagement if there was we would not be regularly replacing ring gears. We even relocate ring gears on unusual engine and transmission combinations. The engine usually stops in the same crank location every time, thus that section of the ring gear receives the most wear. For some reason Geoff you have been one of the luckiest persons in the 356 world! Congratulations. al zim

[Martin Benade]

My fully 6v starter worked quite happily for many years on 12v. I finally replaced it due to a misdiagnosis.

[Geoff Fleming]

Nope...no luck involved. A 12v solenoid reacts to a 12v input, simple. Why would it not mesh with the teeth?
I also know of cars that have been converted and have no problem. When I first had the car, it came with a 6v starter, ( previous owner, not factory), which worked pretty well for a while, then began to grind the ring gear teeth, due to the too-rapid engagement of the Bendix drive, that is how the flywheel teeth are damaged, not by using correct voltage to power the solenoid.
Paul: Are you absolutely sure he didn't use a 6v starter and solenoid after the 12v conversion? Ring gear teeth perhaps previously damaged?
I used to average something like 15,000 miles a year which is more than most modern 356 drivers see in a lifetime and no problem.
If anyone wants to do a test, simply rig up a 6v starter with 12v solenoid on a test bench, using a 356 transmission and see if it doesn't work as I mentioned. After a few hundred tests you will be convinced.

[Brad Ripley]

What happened to the voltage regulator discussion?

[Al Zim]

While you see one example of perfect starter to ring gear alignment, we see a lot of ring gears with the teeth ground off to the point the starter no longer works. It is very hard to extrapolate a curve on starter to ring gear successes from a single point. al zim

[Wes Bender]

What happened to the voltage regulator discussion?

Hi Jack!