Regulator voltage (12V generator system)

Hello!
------

My Beetle (12V, gen) started burning headlight bulbs. Does someone
remember, what was the max voltage for regulated charging voltage?
I measured 14,85 V with "normal" engine revs. Wonder if that is
still in tolerance or do I need to replace the regulator.

---
Olli

Olli Lammi wrote:
> Hello!
> ------
>
> My Beetle (12V, gen) started burning headlight bulbs. Does someone
> remember, what was the max voltage for regulated charging voltage?
> I measured 14,85 V with "normal" engine revs. Wonder if that is
> still in tolerance or do I need to replace the regulator.
>
> ---
> Olli

I would say that is on the high side. At max RPM, voltage
should be 13.5 to 14.5V. And the actual voltage at the
headlamp would be lower.

--

Speedy Jim
http://www.nls.net/mp/volks/

"Speedy Jim" > wrote in message
...
> Olli Lammi wrote:
>> Hello!
>> ------
>>
>> My Beetle (12V, gen) started burning headlight bulbs. Does someone
>> remember, what was the max voltage for regulated charging voltage?
>> I measured 14,85 V with "normal" engine revs. Wonder if that is
>> still in tolerance or do I need to replace the regulator.
>>
>> ---
>> Olli
>
> I would say that is on the high side. At max RPM, voltage
> should be 13.5 to 14.5V. And the actual voltage at the
> headlamp would be lower.

It is important to remember Kerchoff's law. Kerchoff's law simply stated
says that the sum of all voltage drops in a circuit must equal source
voltage.


--
Paul Broadway
www.broadwaypub.com
San Diego, Ca.
(619) 696-9831

>> Olli Lammi wrote:
>>>My Beetle (12V, gen) started burning headlight bulbs. Does someone
>>>remember, what was the max voltage for regulated charging voltage?
>>>I measured 14,85 V with "normal" engine revs. Wonder if that is
>>>still in tolerance or do I need to replace the regulator.
>>
> Speedy Jim wrote:
>> I would say that is on the high side. At max RPM, voltage
>>should be 13.5 to 14.5V. And the actual voltage at the
>>headlamp would be lower.
>
Paul Brodway wrote:
> It is important to remember Kerchoff's law. Kerchoff's law simply stated
> says that the sum of all voltage drops in a circuit must equal source
> voltage.

I measured the voltage between the fusebox and chassis. Most of the
voltage drops should be between the measurement points in this case.

I quess it is time for a new regulator then before that one goes
finally crazy and burns more than just my headlight bulbs.

---
Olli

On Mon, 01 Aug 2005 23:23:17 +0300 Olli Lammi >
wrote:

>My Beetle (12V, gen) started burning headlight bulbs. Does someone
>remember, what was the max voltage for regulated charging voltage?
>I measured 14,85 V with "normal" engine revs. Wonder if that is
>still in tolerance or do I need to replace the regulator.

The voltage at the VR should measure 14.1 - 14.4 V at the VR or
battery. It will measure somewhat lower at the fusebox. This
measurement must be taken at medium or high RPM or the number you
measure will be lower than the actual regulating voltage. You said
"normal" engine revs. If that means driving down the street a 30 mph
(or an equivalent RPM) then that's fine. If you did it at idle, then
your real number is even higher than 14.85V.

At any rate, 14.84 V is too high.

The next question is, "How accurate is your voltmeter?" That COULD be
part of your problem.

It is extremely unusual for a charging system with a Bosch VR to run
high voltage; I've never seen this happen. They always wear out on the
low voltage side. If your voltage really is this high, then either you
have a different VR brand, with a different failure/aging mode, or
there is a short in your wiring somewhere.

I suggest that you try to verify the accuracy of your voltmeter, then
do this test:

Unplug the DF wire from the VR and leave it where it can't short to
anything. With it disconnected, start the car and do your test again.
The voltage should stay between 12 - 13 V. If the voltage goes above
13, you have a wiring problem, either in the DF wire between the VR
and the generator, or inside the generator.

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
-----------------------------------------------

Jim Adney wrote:
>
>>My Beetle (12V, gen) started burning headlight bulbs. Does someone
>>remember, what was the max voltage for regulated charging voltage?
>>I measured 14,85 V with "normal" engine revs. Wonder if that is
>>still in tolerance or do I need to replace the regulator.
>
>
> The voltage at the VR should measure 14.1 - 14.4 V at the VR or
> battery. It will measure somewhat lower at the fusebox. This
> measurement must be taken at medium or high RPM or the number you
> measure will be lower than the actual regulating voltage. You said
> "normal" engine revs. If that means driving down the street a 30 mph
> (or an equivalent RPM) then that's fine. If you did it at idle, then
> your real number is even higher than 14.85V.

I did the test with as high revs that were reasonable to use in
the parking lot car standing at 22 o'clock in fear to disturb
neighbours About 2000 rpm I think.


> At any rate, 14.84 V is too high.
>
> The next question is, "How accurate is your voltmeter?" That COULD be
> part of your problem.

Ok. I have two digital voltmeters available. I did some more tests and
hooked them both meters in parallel to measure voltage between the
B+-post of the voltage regulator and the voltage regulator mounting
bolt. Maybe they both are wrong, but that is not likely.


> It is extremely unusual for a charging system with a Bosch VR to run
> high voltage; I've never seen this happen. They always wear out on the
> low voltage side. If your voltage really is this high, then either you
> have a different VR brand, with a different failure/aging mode, or
> there is a short in your wiring somewhere.

It is a Bosch regulator.


> I suggest that you try to verify the accuracy of your voltmeter, then
> do this test:
>
> Unplug the DF wire from the VR and leave it where it can't short to
> anything. With it disconnected, start the car and do your test again.
> The voltage should stay between 12 - 13 V. If the voltage goes above
> 13, you have a wiring problem, either in the DF wire between the VR
> and the generator, or inside the generator.

Some more measurements (two values for two meters):

Between regulator B+ and GND, normal setup:

engine off: 12.50 V 12.46 V
engine idle: 13.27 V 13.29 V
high revs: 14.75 V 14.73 V

DF-wire loose from the regulator, between reg B+ and GND:

high revs: 12.21 V 12.18 V

So, it seems that the values are quite where they should be except
slightly high voltage with engine revving.

Decided to buy another set of head lamp bulbs (maybe the bulbs were poor
quality) and keep the regulator. Or is this wise move at all?

---
Olli
http://olammi.iki.fi/olammi/beetle/

On Tue, 02 Aug 2005 10:54:23 +0300 Olli Lammi >
wrote:

>Jim Adney wrote:
>>
>>>My Beetle (12V, gen) started burning headlight bulbs. Does someone
>>>remember, what was the max voltage for regulated charging voltage?
>>>I measured 14,85 V with "normal" engine revs. Wonder if that is
>>>still in tolerance or do I need to replace the regulator.
>>
>>
>> The voltage at the VR should measure 14.1 - 14.4 V at the VR or
>> battery. It will measure somewhat lower at the fusebox. This
>> measurement must be taken at medium or high RPM or the number you
>> measure will be lower than the actual regulating voltage. You said
>> "normal" engine revs. If that means driving down the street a 30 mph
>> (or an equivalent RPM) then that's fine. If you did it at idle, then
>> your real number is even higher than 14.85V.
>
>I did the test with as high revs that were reasonable to use in
>the parking lot car standing at 22 o'clock in fear to disturb
>neighbours About 2000 rpm I think.

That sounds just fine.

>> At any rate, 14.84 V is too high.
>>
>> The next question is, "How accurate is your voltmeter?" That COULD be
>> part of your problem.
>
>Ok. I have two digital voltmeters available. I did some more tests and
>hooked them both meters in parallel to measure voltage between the
>B+-post of the voltage regulator and the voltage regulator mounting
>bolt. Maybe they both are wrong, but that is not likely.

I agree. Your numbers are probably good.

>> It is extremely unusual for a charging system with a Bosch VR to run
>> high voltage; I've never seen this happen. They always wear out on the
>> low voltage side. If your voltage really is this high, then either you
>> have a different VR brand, with a different failure/aging mode, or
>> there is a short in your wiring somewhere.
>
>It is a Bosch regulator.

Wow, I'm stunned, but there's always a first time....

>> I suggest that you try to verify the accuracy of your voltmeter, then
>> do this test:
>>
>> Unplug the DF wire from the VR and leave it where it can't short to
>> anything. With it disconnected, start the car and do your test again.
>> The voltage should stay between 12 - 13 V. If the voltage goes above
>> 13, you have a wiring problem, either in the DF wire between the VR
>> and the generator, or inside the generator.
>
>Some more measurements (two values for two meters):
>
>Between regulator B+ and GND, normal setup:
>
> engine off: 12.50 V 12.46 V
> engine idle: 13.27 V 13.29 V
> high revs: 14.75 V 14.73 V
>
>DF-wire loose from the regulator, between reg B+ and GND:
>
> high revs: 12.21 V 12.18 V
>
>So, it seems that the values are quite where they should be except
>slightly high voltage with engine revving.

I agree. This all seems to point to a bad VR. Unless there's any
chance that there's rust, or something conductive caught under the VR
that's shorting out something under there.

>Decided to buy another set of head lamp bulbs (maybe the bulbs were poor
>quality) and keep the regulator. Or is this wise move at all?

I'd replace the VR and repeat the test. I'd hate to see you burn out
another set of headlights, or other bulbs, or the battery....

In the worst case, you'll replace it and find that nothing's changed,
but I think you've done all the tests, done them well, and there's
little room for any other conclusion. There are worse things than
ending up with a good spare VR.

Since this one has an unusual failure mode for a Bosch VR, if you end
up replacing the VR, I'd like to test and dissect your old one. If
you're interested, I'll pay the postage and give you a report on what
I find.

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
-----------------------------------------------

Jim Adney wrote:
>
>>Decided to buy another set of head lamp bulbs (maybe the bulbs were poor
>>quality) and keep the regulator. Or is this wise move at all?
>
>
> I'd replace the VR and repeat the test. I'd hate to see you burn out
> another set of headlights, or other bulbs, or the battery....
>
> In the worst case, you'll replace it and find that nothing's changed,
> but I think you've done all the tests, done them well, and there's
> little room for any other conclusion. There are worse things than
> ending up with a good spare VR.

I bought an aftermarket anonymous Taiwan made regulator today. It looks
overall like the Bosch one and had same terminals. The part says, it
replaces 0.190.350.079 and VW 113-903-803E. Model code was
"Regulator SE-805".

Installed it in my Beetle and run measurements again. Voltage is now
at max 14.25 V when revving (before with Bosch it was 14.75 V).
Now it is in Bentley tolerance (13.5-14.5 V).

Ok. The old one looks at least ok from the top. I don't see any
damage under the VR in the components. Did not open it. There was
nothing under the VR that in my opinion could have shorted something.

The old Bosch one has the following type information on it:

BOSCH
made in Germany
Bosch 0 190 350 068
VA 14V 30A
VW 113 903 803E


> Since this one has an unusual failure mode for a Bosch VR, if you end
> up replacing the VR, I'd like to test and dissect your old one. If
> you're interested, I'll pay the postage and give you a report on what
> I find.

If you really wan't the old Bosch one, I can send it to you.
It is in Finland though, so it will take some time to get to the US.
Send me email with address details if you want it for testing.

---
Olli

That is really close, it actually states that the sum of all potentials in
any closed loop equals zero (0). But yours is a good interpretation to use
in cars.

Joe

On Wed, 03 Aug 2005 22:07:01 +0300 Olli Lammi >
wrote:

>I bought an aftermarket anonymous Taiwan made regulator today. It looks
>overall like the Bosch one and had same terminals. The part says, it
>replaces 0.190.350.079 and VW 113-903-803E. Model code was
>"Regulator SE-805".

I haven't been too impressed with the aftermarket VRs we see here.
They don't seem to last long. Perhaps you get better ones there.

>Installed it in my Beetle and run measurements again. Voltage is now
>at max 14.25 V when revving (before with Bosch it was 14.75 V).
>Now it is in Bentley tolerance (13.5-14.5 V).

Perfect! ;-)

>Ok. The old one looks at least ok from the top. I don't see any
>damage under the VR in the components. Did not open it. There was
>nothing under the VR that in my opinion could have shorted something.
>
>The old Bosch one has the following type information on it:
>
> BOSCH
> made in Germany
> Bosch 0 190 350 068
> VA 14V 30A
> VW 113 903 803E

Could this actually be the original one? If so, it's pretty unusual
for them to have lasted this long.

The fact that it has the VW part # on it indicates that it is either
the original or it was a replacement but bought from a VW dealer. The
ones that came straight from Bosch would carry only the Bosch #, or at
least that's how it works in the US..

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
-----------------------------------------------