Regulator voltage (12V generator system)

Hello!

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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.

Reply to
Olli Lammi
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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.

Reply to
Speedy Jim

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.

Reply to
Paul Broadway

Paul Brodway wrote:

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.

Reply to
Olli Lammi

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 snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

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Reply to
Jim Adney

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.

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 a Bosch regulator.

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?

Reply to
Olli Lammi

That sounds just fine.

I agree. Your numbers are probably good.

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

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.

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.

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----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

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Reply to
Jim Adney

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

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.

Reply to
Olli Lammi

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

Reply to
<josephgliebe

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.

Perfect! ;-)

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..

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----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

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Reply to
Jim Adney

I would not bet too much on parts that say "made in Taiwan". Pretty sure it won't last the 30+ years that the old one did.

I think it is possible that this is the original one. Not sure ofcourse, but that is possible. Or it might be original VR from some other generator equipped VW that one of the POs has bought from a swap meet or something.

Shipping the old VR from Finland to US would cost 23.32 US$. It will take 16-30 days to get there with that price. If you want to test it, one possibility also is that I'll open it for you, take large pictures and send them to you by email (or post links to pictures here, if someone else is interested). Then if you want some more pics or measurements to be carried out, you can tell me what to measure.

Reply to
Olli Lammi

Most of the OG ones over here didn't last even 20 years; 15 was about average. The Bosch replacements didn't do as well

Thanks, but $23 is more than it'w worth to me. If you're able, open it up and just inspect it for problems. If you have a variable voltage power supply connect it across D+ and ground and increase the voltage until you see the regulating relay just pull off its contact. Let me know what the PS voltage is when that happens.

Otherwise, just thanks, and good luck with your replacement.

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----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

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Reply to
Jim Adney

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