# Help Needed for Alternator Problems & Measurements Using VCDS



## WillemBal (Nov 20, 2010)

I’m often wondering whether I’m the only guy on the forum who owns a Phaeton with the dash panel voltmeter sitting between 13.5 and 14 Volt, instead of a rock solid 14 Volts. 
It would be fantastic if some members could provide some feedback of what they are measuring with their VCDS.

The generator performance can be monitored by entering controller 01 (Engine Electronics), then by entering MVB (measuring blocks). Then type 053 in Group A. This will produce the readings of 4 measurements:
Field 1: Engine RPM actual
*Field 2: Engine RPM desired*
*Field 3: Battery Voltage as seen by the Engine ECM*
*Field 4: Generator power in % (0 to 100)*

The latter is the DF value (dynamo field), a value which is reported by the alternator to the J519 module and the ECM. It is the result of the generator's built-in regulator, which controls the power (voltage) output of the generator by means of adjusting the dynamo field current.

It would be very interesting to know what values other forum member are getting for battery voltage and generator power, when RPM is at idle speed (_550 RPM_), slightly higher RPM (i.e.700 RPM) and at 1500 RPM.

Today I measured these values with VCDS and noticed that the % generator load is constantly sitting at 99.2% at 550 RPM, regardless of consumers. The battery voltage never exceeded 13.58 Volts, even though I shut down every possible power consumer (including the rear heater – via the A/C menu –> extra functions). With electrical consumers, the voltage drops a bit, then slowly recovers to the original 13.58 (except at idle RPM). 
The battery voltage stays above 13 Volt most of the time, but occasionally drops down to 12.6 Volts. Increasing engine RPM, does affect the generator load value, but it looks very unstable, sometimes jumping to 0 and anything between 0 and 100. :screwy:

I made a log file (via the same menu in VCDS) and after I’m done with that, I will post the trends. Meanwhile, I’m anxious to hear what values other members are measuring…Perhaps 
what I am seeing is normal behaviour and there is nothing to worry about.


Willem


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## jyoung8607 (Feb 14, 2006)

From memory, I've seen my own generator DF reading near-100% at idle as well but it's not something I've really studied. When I'm headed out tomorrow, I will take some VCDS logs of what you're looking for.

My dash panel voltmeter is generally stable around the 14 volt level. But, on cold mornings for a short while after startup, it can wander around lower at idle engine speeds. I used to see that a lot running my kids up to the bus stop in the morning over the winter. Do you always see lower voltage than you'd like or only just after startup?

At the voltage levels you're seeing, it's quite likely intervention load management is tampering with high-power consumers in the background. You have to be in pretty bad shape to get a warning in the instrument cluster; ILM is active and working on less-important stuff way before that. Watching ILM state in Central Electronics can give you important clues. If you see voltage changes, it may not be changes in alternator output, it may be consumers silently turning on and off. It'll also be tampering with engine idle speed in an effort to raise alternator output.

Since you have that nice solar sunroof and the mythical jack-kit wrench, I'll just bet you have the heated windshield option too. The current draw for that thing is outrageous, 1000 watts I've read, which is north of 80 amps @ 12V. Is it cold enough where you are to have that come on at startup? I seem to remember reading it comes on for two minutes after startup if the outside temperature calls for it. I don't know if turning Climatronic to "OFF" disables it. But, that's something you can see in VCDS with the new Climatronic labels.

Jason


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## PanEuropean (Nov 3, 2001)

Hi Willem:

FYI, the voltage display in the instrument panel is 'normalized' to show 14 volts even if the actual voltage is slightly above or below that level - same way that the coolant temperature gauge is normalized to show 90° even if the coolant temperature is slightly above or below that level. I think that VW does this to stop people from worrying about minor fluctuations. If either of these two values moves significantly away from the norm, then the gauges will display the actual measurement accurately.

Having said all that... I'm wondering if what you might be encountering is a slight error in calibration of the needle-indicator in your instrument cluster. In other words, the needle might be thinking it is pointing at 14 volts, but due to 'mechanical' error that has crept into the needle assembly (the indicator itself), it is not actually pointing at 14 volts.

I'll be getting back to Vancouver Island this weekend, and will have a look at the MVBs on my W12 Phaeton and post them here for you. But, I won't be able to do that the first day I get back - I have not used the car since late February (have not been home since late February), and I am pretty sure that until I leave the 2 batteries on external charge overnight, any kind of electrical measurements from my car would suggest that the car is clinically dead... 

Michael


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## PanEuropean (Nov 3, 2001)

jyoung8607 said:


> ...I'll just bet you have the heated windshield option too.... I seem to remember reading it comes on for two minutes after startup if the outside temperature calls for it. I don't know if turning Climatronic to "OFF" disables it.


Hi Willem:

Jason raises an interesting point about the heated windshield.

If you want to shut down all of the electrical power consumption from the HVAC system, press the AC button on the middle display, then turn the fan control to 0 (zero). That will shut down everything - circulating fans, AC compressor, PTC heaters for the back seat area, the works.

I also think that you will not be able to observe a credible (for greater clarity: 'stabilized') current demand until the engine has been running for about 5 minutes, simply because the starter battery will have discharged somewhat during the engine start process, and it can take up to 5 minutes after start before the right side battery load diminishes down to a point where it is not significantly distorting overall vehicle electrical load measurement.

Michael


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## Paximus (Aug 26, 2011)

> WillemBal:
> The generator performance can be monitored by entering controller 01 (Engine Electronics), then by entering MVB (measuring blocks). Then type 053 in Group A. This will produce the readings of 4 measurements:
> Field 1: Engine RPM actual
> Field 2: Engine RPM desired
> ...



Hi Willem,

Here's the data on the V10, in case it's similar to the W12. I can't think why it should be designed differently, except for the idle speed.

Car: standing for 20 hours, ambient 10 degC.
Batteries: both new 2 weeks ago.

-- Open car doors for 10 mins. 
-- Start VCDS in Controller 01, Group 53 [_not available_]
-- Turn on car (not engine). Dash voltmeter reads 11.8V rising to 12.75V over 30 secs
-- Start engine. Dash voltmeter drops to 11.6V for 5 secs, then rises immediately to 14.1V
-- Change VCDS to Group 16 [_Reading available_]
-- Revs 609 - Load 78% - 13.6V
-- Revs 714 - Load 74% - 13.6V
-- Revs 800 - Load 64% - 13.6V
-- Revs 1000 - Load 52% - 13.6V
-- NB - Group 16 volts drop from 13.6V to 13.53V for 2 secs whenever engine speed is changed
-- Dash voltmeter reads 14.1V throughout, other than as noted above.


Sorry I missed the initial VCDS volts, the V10 ECU has the battery data on a different Group from the W12 and it took me a few seconds to figure this out. Its alternator Group 16 did not show me desired idle speed, only actual.

Chris


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## WillemBal (Nov 20, 2010)

jyoung8607 said:


> Since you have that nice solar sunroof and the mythical jack-kit wrench, I'll just bet you have the heated windshield option too. The current draw for that thing is outrageous, 1000 watts I've read, which is north of 80 amps @ 12V. Is it cold enough where you are to have that come on at startup


Hi Jason,

I’m afraid I’ve to admit that I don’t have the heated windshield (I think). It is not so cold now, about 10 ⁰C. Anyway, I rarely see the dash panel meter on 14 Volt, it is more like 13.5 Volt, sometimes raising to near 14 Volt on very rare occasions, and not for longer periods than a few minutes. I never see warning signs in the instrument cluster though.
I once reset the ILM counter to 0 and two weeks later, it was reading about 3 (3 interventions), one month later back to 14 (the maximum reading). Is this what you mean with the ILM status? I think that the amount of interventions is not enough to cause constant variations in the volt reading.

Willem


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## WillemBal (Nov 20, 2010)

PanEuropean said:


> Hi Willem:
> FYI, the voltage display in the instrument panel is 'normalized' to show 14 volts even if the actual voltage is slightly above or below that level - same way that the coolant temperature gauge is normalized to show 90° even if the coolant temperature is slightly above or below that level.  I think that VW does this to stop people from worrying about minor fluctuations.


Hi Michael,

Is that really true? I think that it would be very naughty of VW to design it this way. :sly:



> Having said all that... I'm wondering if what you might be encountering is a slight error in calibration of the needle-indicator in your instrument cluster. In other words, the needle might be thinking it is pointing at 14 volts, but due to 'mechanical' error that has crept into the needle assembly (the indicator itself), it is not actually pointing at 14 volts.


That is what I hoped too… but on all occasions where I compared its reading with a calibrated DMM, there was no more difference than 0.25 Volts.



> …and I am pretty sure that until I leave the 2 batteries on external charge overnight, any kind of electrical measurements from my car would suggest that the car is clinically dead... [QUOTE/]
> 
> Wow, if you could do that...It would be very interesting to see what measurements you are getting with practically discharged batteries.


If you want to shut down all of the electrical power consumption from the HVAC system, press the AC button on the middle display, then turn the fan control to 0 (zero). That will shut down everything - circulating fans, AC compressor, PTC heaters for the back seat area, the works. [/QUOTE]

Very good suggestion. I did this… and it helps a bit. The voltage increases about 0.3 Volts (almost 14 on the dash) and the DFM occasionally leaves the 100% with random numbers between 0 and 99. It is this crazy DFM reading which makes me believe that something is wrong



> I also think that you will not be able to observe a credible (for greater clarity: 'stabilized') current demand until the engine has been running for about 5 minutes, simply because the starter battery will have discharged somewhat during the engine start process, and it can take up to 5 minutes after start before the right side battery load diminishes down to a point where it is not significantly distorting overall vehicle electrical load measurement.


This is an interesting point. I made oscilloscope screenshots (also possible with VCDS) of the voltage of both batteries. I will post the results in a next post. It is amazing to see how quickly the starter battery recovers its original voltage (almost 15 Volts). But, the consumed energy during starting is not so much though. 300 amps, during 1 second, it is just 0.1 Ah...

Willem


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## WillemBal (Nov 20, 2010)

Hi Chris,

Thank you for your data. This is very useful information! And wow, that is what I would call a good charging system! Your % load reading (coming from DFM – Dynamo Field Monitor) at least decreases in a logical way. It is inversely proportional to the revs (makes perfect sense). Even though your dash meter shows 14.1 Volt, the reported 13.6 Volt looks like a good charging voltage. Mine doesn’t do that at all. 

Willem


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## n968412L (Apr 23, 2009)

Dear Willem - I think both my Pheatons show about 14.2V when running. I'll try and take measurements over the weekend (unless it rains hard!!)

Regards

M


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## WillemBal (Nov 20, 2010)

n968412L said:


> Dear Willem - I think both my Pheatons show about 14.2V when running. I'll try and take measurements over the weekend (unless it rains hard!!)


Hello Mike,

Believe it or not... there is nothing better you can do than sitting in your warm car and doing these measurements while it rains hard!
Thanks in advance,

Willem


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## jyoung8607 (Feb 14, 2006)

WillemBal said:


> Anyway, I rarely see the dash panel meter on 14 Volt, it is more like 13.5 Volt, sometimes raising to near 14 Volt on very rare occasions, and not for longer periods than a few minutes. I never see warning signs in the instrument cluster though.


If your voltmeter reading varies at all while the car is warmed up and driving down the road normally, then I think your experience is different from everyone else here and there might be a problem.



WillemBal said:


> I once reset the ILM counter to 0 and two weeks later, it was reading about 3 (3 interventions), one month later back to 14 (the maximum reading). Is this what you mean with the ILM status? I think that the amount of interventions is not enough to cause constant variations in the volt reading.


That isn't number of times ILM happened. It's the deepest stage of ILM your Phaeton has encountered since the last reset of the ILM value. Your car could have been under ILM a thousand times but only gotten to stage three each time, and that value would still be three. Stage 14 means it ran through everything it's got, which should be just about impossible with the engine running but is very possible with the engine shut off and the battery running down.

Unfortunately, it's hard to get solid documentation on ILM. There's some good basic info in the self-study guides. There's more detailed information in a TSB Volkswagen put out a while back, but it partially conflicts with the self-study guides and only shows 12 of the 14 stages. I studied this stuff in detail when I was documenting the Climatronic response to ILM.

These are my notes from a few months ago, showing what I think are the real ILM stages. It's the 12-item priority list from the TSB, with two missing items inserted based on the VW SSP at #2 and #6.

1 - PTC reduce 25%
2 - from SSP, seat heating to 50%
3 - Rear defrost reduce 50%
4 - PTC reduce 50%
5 - Heated seats and ventilation off
6 - from SSP, heated windshield off
7 - PTC reduce 75%
8 - Wiper park position and washer nozzle heating off
9 - Side mirror heating
10 - PTC reduce 100%
11 - Heated steering wheel off
12 - Rear defrost off
13 - HVAC fan 30% reduction
14 - Compressor shutoff

I believe the instrument cluster "consumers being shut off" warning happens somewhere around stage 12 or 13. Central Electronics is bad about giving you live ILM state, I think it only gives you ON/OFF and the deepest state ever reached since reset. But, you can get a pretty good sense by watching Climatronic MVB 043. Columns are PTC heating, windshield heating, unknown/irrelevant and HVAC fan/compressor respectively.

0 0 - 0 ILM not currently active
1 0 - 0 ILM stage 1
2 0 - 0 ILM stage 4
2 1 - 0 ILM stage 6
3 1 - 0 ILM stage 7
4 1 - 0 ILM stage 10
4 1 - 1 ILM stage 13
4 1 - 2 ILM stage 14

You'll see the car go through the above sequence, in order, if you sit in the car and let the battery run down somewhat. Then if you clip on your battery charger, you can actually watch it slowly roll back up the ILM priority list as system voltage is restored to normal levels.

Jason


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## PanEuropean (Nov 3, 2001)

There is a post listed in the TOC/FAQ (Table of Contents / Frequently Asked Questions) that provides quite a bit of information about ILM (Intervention Load Management) - you can find it at this link: TB: Intervention Load Management on the Phaeton.

There is also a 12 page technical bulletin (TB) from VW attached to that post that provides considerable additional detail about ILM.

Michael


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## n968412L (Apr 23, 2009)

Willem - below is some info from my GP0 V10.
Not quite got the hang of all aspects of VCDS... and my excel skills are not great - but here is graph of ECU volts from a cold start. Missed a couple of ignition off/on cylces first.. but this is the first engine start of the day.

Then a longer run immediately afterwards.

Having reversed the run - return trip 6.5 mins, the ECU has pretty stable 13.38 volts. However voltmeter showing 14V.

Pictures show voltmeter with ignition on - ie the climb to 13V within a few seconds, then the volts shortly after engine start. The last picture trys to show the same reading but with the camera closer and normal to the voltmeter so that I'm trying to reduce parallax error. I guess this is responsible for why I've assumed the voltmeter is steady at 14.2V... in practice I think it's 14V when I've put my head right in front of it.

I might do the GP1 V6 later on today or tomorrow - but from previous casual observation I would think it would be very similar.

Let me know if you want any of the data etc - I can PM it to you or something.

Regards
M


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## WillemBal (Nov 20, 2010)

n968412L said:


> I might do the GP1 V6 later on today or tomorrow - but from previous casual observation I would think it would be very similar.
> Let me know if you want any of the data etc - I can PM it to you or something.
> M


Hi Mike,

You sure are getting the hang of it! Those are nice trends, similar to mine. The generator produces 13.3 Volts, which seems a bit low. Perhaps VW DID intentionally install a dash panel meter that reads 14 Volts when there is nothing to worry about, and only fluctuates when there are big deviations from the ideal situation. Then I will have something to worry about.

Your log file probably also contains the data of the DFM, is you used MVB of the engine control module. When you send me the log file, I will merge your information in one trend, so that the difference between our cars and generators becomes more easy to see. I will send you a PM.

Willem


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## Paximus (Aug 26, 2011)

As Michael said, the consensus is that the dash voltmeter does normalise to 14V, probably when the power supply is between 13.5 and 14.5V or thereabouts.

Chris


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## WillemBal (Nov 20, 2010)

Paximus said:


> As Michael said, the consensus is that the dash voltmeter does normalise to 14V, probably when the power supply is between 13.5 and 14.5V or thereabouts.
> 
> Chris


Hi Chris,

That sounds worrying. My meter DOES follow every single variation in the battery voltage. I checked that with VCDS and with a DMM connected to the lighter socket. It implies that IF VW did this on purpose, then there IS something wrong with my generator. And both your generator and Mike's one are OK.

Regards,

Willem


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## WillemBal (Nov 20, 2010)

Here are some first trends, based on the data of the log file during a 10 minute test drive.

The first trend below shows the battery voltage & load% (Dynamo Field value) versus time. I drove the car as usual, so the RPM was normally above idle.










During the first 250 seconds I, all electrical consumers were switched off (A/C off as well). Then, from 250 to 400 seconds, the A/C was on. From 400 to 550 seconds, I switched on the rear wind shield heater, dipped beam and the fog lights. And after 550 seconds, I switched all off except for the A/C.

As you can see, there is no clear relationship between the actual load (the consumers) and the generator load% as reported by VCDS. It is easy to see though, that with everything switched on, the generator has a hard time to keep the voltage above 12.5 Volts.

The below trend shows the "relationship" between battery voltage and load%. All red squares are individual measurements of the VCDS of my car. The blue dots represent the data of Chris' car.










As you can see, my own measurements are virtually random. There is no logical relationship between generator load and RPM. 
When you look at the blue dots (data reported by Chris), you can see that there is a good relationship between RPM and load%.

The higher the RPM of the engine, the higher the RPM of the generator and the higher the voltage output (when the DFM is not adjusted). This principle is similar to that of a bicycle dynamo; the faster it rotates, the more voltage it generates.

In a car's electrical system, this effect is compensated by regulating the field strength of the rotor poles. This is done by the regulator, which is integrated the generator and is not controlled by any control module at all. Therefore, I would expect that the reported generator load % (which is basically the field current or DFM) would drop with increasing RPM. This makes me think that the generator is not working as it should, or at least not when there is a high electrical demand.

Willem


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## Paximus (Aug 26, 2011)

Hi Willem,

Very useful presentation of your data.

Sorry I can't replicate your 10-min drive right now, my laptop battery is shot and I have to use mains power, and the other one is a Mac. Plugging in a 10amp 12V DC-AC converter would distort the figures!

I am sure you posted when you fitted new batteries, but I can't remember.

The random distribution of those outlier load % figures looks very unhappy. Unless it's something to do with the small reduction in power supply voltage every time the engine revs change, which they do frequently on a normal drive, naturally. Perhaps the alternator's voltage regulator drops the volts or puts in a response time delay when it sees an output fluctuation, so as not to ever run over-volts. Or the ECU too busy to bother to report on Group 53.

Other than that, it does look as if the alternator is not delivering power predictably, or else the % load reporting wire from the alternator is loose!

Is there any noise on the AM radio?

Chris


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## WillemBal (Nov 20, 2010)

Hi Chris and Mike,
You both seem to have a V10. The topology of the groups of the ECM is apparently not identical to that of the W12, also as far as the group 053 is concerned. Chris already mentioned that he found “load %” in group 016, however I overlooked that information initially. Mike made a log file with group 016 of which I now made a trend versus RPM. It is very likely that Group 016 (Controller 01 of V10) is in fact the generator load%. Perhaps the label file of the V10 engine can confirm this, but it doesn’t seem to exist in my VCDS or I erased it. (Label file for controller 070 906 016 B).

The trend below shows how the load % responds to the RPM of the engine. As you can see, it is quite different than my own W12. It is much more stable and the variations can be directly related to RPM. Another factor is the electrical power consumption during the ride, which is of course depending on many factors. Everything in the car uses electricity, i.e. gear shifts, A/C, rear PTC heater etc. So it is only natural that the load % is not only inversely proportional to the RPM of the engine. 










My conclusion is that both alternators are working fine.

Willem


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## WillemBal (Nov 20, 2010)

Hi Jason & Michael,

I made a log file using Climatronic MVB 043. The result is given below:










Only during a very short period of time, during the start procedure, some power consumers are shut down.
The status of the MVB 043 is illustrated in below picture:










To me, it looks logical that these power consumers are shut down during cranking the engine and up to 5 seconds thereafter, because the ECM consumes quite a bit of energy. I stopped the car for some time (from 700 up to 1350 seconds in the first trend), and then started the car again with the same result.

My problem is actually not that the engine shuts down electrical consumers while driving. During the winter time, I used the auxiliary heater every day, for about 10 to 15 minutes per day. When I charge the battery with an external charger, I can use the heater about 5 times per week. The 6th time, it will not turn on. When I make a scan, these errors are reported:

Address 07: Control Head Labels: 3D0-035-00x-07.lbl
Part No: 3D0 035 007 L
Component: ZAB COCKPIT 0223 
Coding: 0500735
Shop #: WSC 01065 000 00000
VCID: 2240E8D6C295E70C

1 Fault Found 
00668 - Supply Voltage Terminal 30 
002 - Lower Limit Exceeded - Intermittent

Address 09: Cent. Elect. Labels: 3D0-937-049.lbl
Part No: 3D0 937 049 G
Component: STG.Bordnetz 5001 
Coding: 0000003
Shop #: WSC 00404 211 75534
VCID: 2E580CE6864D536C

1 Fault Found 
00907 - Intervention load Management 
000 - - 

and:
Address 18: Aux. Heat Labels: User\3D0-815-005.lbl
Part No: 3D0 815 005 Q
Component: Standheizung 2426 
Shop #: WSC 00000 000 00000
VCID: 2B5E05F2B55F2644

1 Fault Found 
01444 - Under-Voltage Shut-Off (Automatic) 
000 - - - Intermittent

Half a year ago, I went to the dealer and one of the things I asked, was to check the state of the battery. After completion of this test, which I was allowed to witness, the technician gave me a little printout of the result. This report told me that the test apparently was done using a Midtronics device, Inpect 65, version 11 @2005, with the following details:

•	Charge conditions: 12.21 Volt
•	Measured: 798A (SAE)
•	Value: 520A (SAE).
Below this text, to graph bars telling me that the battery condition was 100% (798A is a lot better than the specified 520A !) and charge condition 40%. Conclusion: battery is excellent, but needs recharging. A remarkable result, given that I had just been recharging my battery 2 days before. And it was in the middle of the summer, so there couldn’t have been much battery drain due to “cold weather” electricity consumers, like defrosters, PTC rear heaters and so on.

I also checked the battery drain using a current clamp. No more than 35 mA each time, although it can take up to 10 minutes before this quiescent current is reached.

This is why I suspect my generator...and hope to find an easy way to use VCDS in diagnosing the cause of the problem. Which is apparently not so easy.

Willem


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## WillemBal (Nov 20, 2010)

*The role of the dash panel voltmeter*

Both Mike and Chris reported much higher readings on their the dash panel voltmeter than what was reported by VCDS. An important reason for this difference is that they apparently are not measuring the same.
The voltage, as reported by VCDS is coming from the Battery Charge monitor, which is in the trunk.
The dash panel meter is connected to the generator directly, which is in the front. This is what can be concluded from the electrical diagram of the engine (not the Power Distribution diagram)
Although generator and battery are linked together, a difference in voltage may exist as the result of internal resistance of the cable (6 meters of 50 mm2 wire), where it not only feeds the battery, but also some consumers in the aft side of the car, such as rear PTC heaters, rear windshield heaters etc.)

Yesterday I measured the difference between generator connection (TV22) under the hood and the battery. This difference varied between 0.2 Volts (no consumers) and 0.4 Volts (A/C with PTC heater & rear windshield heater on).

The conclusion therefore is that the dash panel meter monitors the operation of the generator. My theory is that when the dash panel meter is indicating a rock solid 14 Volts, then the generator is doing exactly what it is supposed (designed) to do: to supply a constant voltage, regardless of engine RPM and electrical power consumption. And the lower voltage on the battery is simply the result of some voltage drop over the connecting cable (as the result of the high rear consumption plus the charge current)

Willem


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## n968412L (Apr 23, 2009)

Hi Willem- I'll post you two more logs I made today. One again from GP0 V10 and the other from GP1 V6. If anyone knows where the alternator loading measurement block is for the V6.... can they tell me - 'cos I can't find it.

And I have to question whether the indication in group 16 for the V10 is actually a loading... it is certainly not obvious to me why loading should have an inverse relationship with speed - unless it is torque. I think the alternator controller will be trying to provide steady voltage... I also think that current will be limited by the synchronous reactance of the alternator... although there are so many electronic loads (eg the dc dc converter to charge the starting battery) that predicting how loading will vary is a bit beyond me. And the real problem I have is this measuring block shows 20% load with the alternator stationery.... I can't get my head round that. Again from memory I think the alternator will have a wound rotor to generate a DC magnetic field.. so maybe this field current? I think voltage is proportional to speed, so a higher excitation (field) current at lower revs would probably be right to keep a contstant terminal voltage. Maybe this is what you meant, Willem?

Whatever it is, it would be nice to find it in the V6 so we can do another comparison!

Regards

M


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## Paximus (Aug 26, 2011)

That VWA Tech Bulletin about load shedding that Michael/PanEuropean posted says that the V8 does not report the % load value in Group 53, because it doesn't use it.

Maybe the V6 is the same, ie that value is not present in VCDS.

I see in the VW drawings that some alternators have the voltage regulator shown as a distinct module in the alternator assembly, which might imply it uses a different (electronically modified) mechanism rather than raw feedback reactance to stabilise the output voltage with current load and rpm variations.

In which case there's a discrete part in the alternator that can misbehave.

BTW, did you check the AM radio for hash? Those random load values bother me, like there's some sparking or similar!

Chris


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## WillemBal (Nov 20, 2010)

n968412L said:


> ... I think the alternator will have a wound rotor to generate a DC magnetic field.. so maybe this field current?


That's right. It has a wound rotor with 6 pole-pairs, i.e. 12 poles all together. These poles are weakly magnetized. All poles have one common winding which is called the field. The higher the current through the field winding, the higher the magnetic field each pole will generate. And the higher the magnetic field (change) generated in each stator winding, the higher the output voltage.



> I think voltage is proportional to speed, so a higher excitation (field) current at lower revs would probably be right to keep a constant terminal voltage. Maybe this is what you meant, Willem?


Exactly right. The situation as far as this aspect of the generator is concerned, isn't different from an old-fashioned bicycle dynamo. The faster you drive with the bicycle, the faster the dynamo RPM will be and the more light you will have. But permanent and strong magnet poles are not going to work for a car's electrical system.
The field poles of a car's generator are only weakly magnetized to avoid a too high voltage at high RPM. The field winding is used to increase the magnetic field flux of the poles at low revs, compensating for the RPM-output voltage effect.
The regulator, which is an integral component of the generator, measures the output voltage. When it is (slightly) too low, it increases the field current. This results in a higher flux in the rotor, resulting in a higher output voltage. 

So you are absolutely right about the function of the % load value. It is nothing else than the amount of current through the field winding (of the rotor). More electrical load at the same RPM will result in an increase of this value (in order to provide more output).
When the load remains constant, and the RPM varies, then you would normally see the field current decrease when the RPM increases.

Willem


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## WillemBal (Nov 20, 2010)

Paximus said:


> That VWA Tech Bulletin about load shedding that Michael/PanEuropean posted says that the V8 does not report the % load value in Group 53, because it doesn't use it.
> Maybe the V6 is the same, ie that value is not present in VCDS.


The same thought crossed my mind. What is strange though, that the label file of a V8 *does* have Group 53 and *including* generator load. (i.e. 4D0-907-560-BGH.lbl)

However, the label file for the V6 engine appears to be missing: 3D0 907 401. Also the V10 label file is missing (070 906 016) or it is part of a re-direct file.
I think we need help from the VCDS label specialists. Perhaps making a pre-label file helps us to get a listing of all groups?



> I see in the VW drawings that some alternators have the voltage regulator shown as a distinct module in the alternator assembly, which might imply it uses a different (electronically modified) mechanism rather than raw feedback reactance to stabilise the output voltage with current load and rpm variations.


I think that you are referring to "C1", the voltage regulator. That part is included in the generator. I guess we all would like to think that the generator is something special and that it is controlled by ECM's, ILM's etc. This is not the case. The generator only has 4 connections. The chassis, which is ground. The B+ connection is connected to the battery. Then there is DFM (Dynamo Field Monitor), which allows us to monitor the duty cycle modulation of the field (current). This signal is fed into the ECM, which converts it into the Generator Load % value.
The final connection is the "L" terminal. This L connection has a very cryptic description:
_Lamp terminal low side driver; relay terminal high side driver_. It is a very "old" terminal, used in most vehicles, practically since the invention of the dynamo. "L" is primarily used to light the Generator Warning Lamp in the instrument cluster. For instance, when the generator is not functional, the voltage on the L terminal will be low, and a warning light can be lit (as the other side is connected to the battery +). When the generator starts functioning, the L terminal adapts the voltage of the generator, or better, the D+ of the generator. Then the same L terminal can be used to monitor/estimate the generator output. And I'm starting to believe that this is actually happening. The L terminal *is* connected to J285 Instrument Cluster Module. Then it makes perfect sense (to me), to use the L signal for both the Generator Warning Lamp (K2) _and_ the dash panel meter.



> In which case there's a discrete part in the alternator that can misbehave.


All I can think of now, is worn brushes. 



> BTW, did you check the AM radio for hash? Those random load values bother me, like there's some sparking or similar!


AM is not particularly noisier with the engine on. But it is some time ago I checked this. I will do that again tomorrow.

Willem


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## Paximus (Aug 26, 2011)

You know far more than I do about alternators!

I was thinking of the Hitachi voltage regulator part 077 903 803C, item (4) in the drawing, but I don't even know what model of Phaeton that alternator is for... It's certainly not a V10, which is gear-driven.

And isn't yours water-cooled, somehow?

Regards,
Chris


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## WillemBal (Nov 20, 2010)

Paximus said:


> You know far more than I do about alternators!


Long time ago I kept myself busy with windmills, trying to store and conserve energy...all this idealistic thinking vanished since I'm driving a Phaeton. 

Yes, the W12 generator is water cooled. The water cooling has been added to make it more silent. It looks like this:









The essential electrical components (12 diode rectifier block and the regulator) are located at the left side of the stator housing.

Your drawing shows the components which can be replaced. Strange enough, the components which may fail, like diodes, regulators and brushed, aren't listed. 

Willem


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## PanEuropean (Nov 3, 2001)

Hi Willem:

This conversation has climbed way above my 'service ceiling' so far as my ability to comprehend it is concerned - I have never been able to figure out electricity (although I can tell the difference between a volt and an amp).

Anyway - I did get back home yesterday, and after charging up both of the batteries in my car using an external charger (the car had not been used since February, although it did start and run just fine when I got into it), I observed the measurements you asked for.

MVB 053/3 in the engine controller of my W12 remained pretty constant at 13.2 volts regardless of engine RPM (RPM range was 550 to 1,000). 

MVB 053/4 appeared to be fixed at 99.2% when the engine was idling. When I increased the engine speed above about 700 RPM (range between 700 RPM and 1,000 RPM), the reading flickered rapidly between 99.2 and single digits, with 99.2% predominating.

By way of comparison, MVB group 007 of controller 09 (the central electrical controller) showed a pretty constant 13.7V for the left battery and 14.65V for the right battery, regardless of RPM.

If it puts your mind at ease - I have never heard of anyone having to replace a generator on a W12 powered Phaeton.

You mentioned midway above that when you operate your auxiliary heater, you get about 5 cycles out of it before the battery voltage declines to a point where the heater shuts down. I suspect that (like me) you have a pretty short commute between your home and your workplace, and the batteries are not getting fully charged up during the short drive from home to work each weekday.

My average driving cycle is about 1.5 to 2 km; rarely over 2 km per cycle. Heck, the engine doesn't ever get a chance to warm up, let alone the battery getting a chance to charge. I need to put my left battery on an external charger once per month to make up the accumulated deficit. Even though I replaced the left battery about a year ago, I still have to do this, so the need for a periodic external charge is not a function of age of the battery.

Michael


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## jyoung8607 (Feb 14, 2006)

WillemBal said:


> To me, it looks logical that these power consumers are shut down during cranking the engine and up to 5 seconds thereafter, because the ECM consumes quite a bit of energy. I stopped the car for some time (from 700 up to 1350 seconds in the first trend), and then started the car again with the same result.


I don't think it's really unique to the moment of trying to start the engine. They were shut down as soon as the vehicle was turned on and available voltage was below a threshold where ILM needed to act. They get turned back on as soon as the alternator is running and the ILM algorithm decides it's safe.

I was bringing ILM into the conversation because in my experience, if my voltmeter is wandering down below 14V, I often see ILM actively managing stuff like the defroster. This would be invisible to the driver unless they were specifically looking for it with VCDS. And that might have an impact on the very detailed readings you're trying to take. Just wanted you to keep it in mind.



WillemBal said:


> My problem is actually not that the engine shuts down electrical consumers while driving. During the winter time, I used the auxiliary heater every day, for about 10 to 15 minutes per day. When I charge the battery with an external charger, I can use the heater about 5 times per week. The 6th time, it will not turn on. When I make a scan, these errors are reported:
> 
> ...


Okay, so that tells us two things. One, your VPS battery is seeing a lot of deep cycles. An AGM battery will tolerate that somewhat, but not that often and not forever. Two, your vehicle charging system isn't able to keep the battery topped up on its own. This could be as simple as not driving very often or driving on very short trips, or a battery in poor condition, or the alternator not putting out enough current.

If your car was topped-up on an external charger just prior to starting, do you get better voltage readings?



WillemBal said:


> Half a year ago, I went to the dealer and one of the things I asked, was to check the state of the battery. After completion of this test, which I was allowed to witness, the technician gave me a little printout of the result. This report told me that the test apparently was done using a Midtronics device, Inpect 65, version 11 @2005, with the following details:
> 
> •	Charge conditions: 12.21 Volt
> •	Measured: 798A (SAE)
> ...


Your tech put the wrong figure in his tester. The measured value is valid, but if he's doing the SAE CCA test, the SAE battery rating is 850A - see the label on the battery, "850A EN/SAE 520A DIN". I found a conversion chart as well, it's about halfway down. You can see the two ratings line up roughly on that chart. Also, measuring SAE or DIN CCA (very brief, very high current test) may not tell you much about the battery's reserve capacity, endurance under a low current draw which is exactly what you need from a Phaeton VPS battery.



WillemBal said:


> I also checked the battery drain using a current clamp. No more than 35 mA each time, although it can take up to 10 minutes before this quiescent current is reached.


That's good to know, and a very acceptable number.

Jason


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## jyoung8607 (Feb 14, 2006)

PanEuropean said:


> MVB 053/3 in the engine controller of my W12 remained pretty constant at 13.2 volts regardless of engine RPM (RPM range was 550 to 1,000).
> 
> MVB 052/4 appeared to be fixed at 99.2% when the engine was idling. When I increased the engine speed above about 700 RPM (range between 700 RPM and 1,000 RPM), the reading flickered rapidly between 99.2 and single digits, with 99.2% predominating.
> 
> By way of comparison, MVB group 007 of controller 09 (the central electrical controller) showed a pretty constant 13.7V for the left battery and 14.65V for the right battery, regardless of RPM.


Readings from my car are very consistent with this.

Willem, I emailed you some VCDS logs from my car. You already have the Excel charts built the way you want, so I'll let you integrate and compare the data however you like.

I think we are all seeing the same generator-DF oscillating values. I'm not an expert in alternator design and function. Is it possible the reading we're being shown is an instantaneous sample of a PWM control signal? It would account for "random" values being shown when less-than-full output is called for.



PanEuropean said:


> You mentioned midway above that when you operate your auxiliary heater, you get about 5 cycles out of it before the battery voltage declines to a point where the heater shuts down. I suspect that (like me) you have a pretty short commute between your home and your workplace, and the batteries are not getting fully charged up during the short drive from home to work each weekday.
> 
> My average driving cycle is about 1.5 to 2 km; rarely over 2 km per cycle. Heck, the engine doesn't ever get a chance to warm up, let alone the battery getting a chance to charge. I need to put my left battery on an external charger once per month to make up the accumulated deficit. Even though I replaced the left battery about a year ago, I still have to do this, so the need for a periodic external charge is not a function of age of the battery.


I would concur with this. Even if you don't currently have winter-time electrical loads, you'll eventually get behind on charging the battery if all you do is very short trips.

I don't think you mentioned it above - what's the manufacturing date on your VPS and starter batteries?

You mention that you need to run your auxiliary heater (you and all your nice Euro-only options! ). That implies that you park outside. You might consider a solar charger semi-permanently installed on the hat shelf. The W12 reflective glass will cut down on output, but it'll be better than nothing. Or, tweak your solar sunroof wiring a bit. 

Jason


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## WillemBal (Nov 20, 2010)

PanEuropean said:


> This conversation has climbed way above my 'service ceiling' so far as my ability to comprehend it is concerned....


Hi Michael,
Don't worry, you probably are not the only one... I just hope that we can find a quick and easy method and standards to determine the condition of the generator and the battery.



> MVB 053/3 in the engine controller of my W12 remained pretty constant at 13.2 volts regardless of engine RPM (RPM range was 550 to 1,000).
> MVB 053/4 appeared to be fixed at 99.2% when the engine was idling. When I increased the engine speed above about 700 RPM (range between 700 RPM and 1,000 RPM), the reading flickered rapidly between 99.2 and single digits, with 99.2% predominating.


That is about the same as what Jason observed (I'll post some trends later). 



> By way of comparison, MVB group 007 of controller 09 (the central electrical controller) showed a pretty constant 13.7V for the left battery and 14.65V for the right battery, regardless of RPM.


That looks OK to me. I'm trying to figure out where all these voltage readings are coming from. It is possible that the Central Electrical Controller (06) and the ECM have their own voltmeter built-in, to report eventual problems. Some difference in voltage reading can be expected then.



> If it puts your mind at ease - I have never heard of anyone having to replace a generator on a W12 powered Phaeton.


I think that the generator itself is a sturdy design. But its output may be a bit tightly specified, given the very large power consumption of the W12 engine itself and the many power consumers. And as a result, there is little juice left to recharge the battery. On the other hand, soon I will have to replace the serpentine belt. This seems to be an excellent opportunity to inspect the alternator. If everything looks OK, my mind will be put at ease... 



> Even though I replaced the left battery about a year ago, I still have to do this, so the need for a periodic external charge is not a function of age of the battery.


A healthy battery sure helps to avoid a lot of problem. How many batteries did you already replace since it was new? Mine was replaced with an original battery in June, 2009. And the battery itself was manufactured in 2009 as well. Is it time for a new battery already?



jyoung8607 said:


> .... I often see ILM actively managing stuff like the defroster. This would be invisible to the driver unless ....


Thanks Jason, I didn't know this.



> If your car was topped-up on an external charger just prior to starting, do you get better voltage readings?


Somewhere in the range between 13.65 and 13. 85 Volt. But never 14.2 Volt. I did this log some time ago, with battery voltages reported by the battery monitor controller.



> Your tech put the wrong figure in his tester


OMG.. This test was done by the same tech who tried to connect his battery maintainer on the jump start posts under the bonnet.  But I'm glad he tested the LH and not the starter battery.



> The measured value is valid, but if he's doing the SAE CCA test, the SAE battery rating is 850A - "850A EN/SAE 520A DIN".


So the measurement result was 440A DIN in reality. I can imagine that 520A DIN is the specification of a new battery. But what is the criterion to reject a battery which has been in service? Is a measured 440A DIN acceptable?



> ... endurance under a low current draw which is exactly what you need from a Phaeton VPS battery.


Well... what I really need is something that can top off the battery while driving 



> Willem, I emailed you some VCDS logs from my car. You already have the Excel charts built the way you want, so I'll let you integrate and compare the data however you like.


I'm working on them right now!



> I think we are all seeing the same generator-DF oscillating values.


All 3 W12's have pretty much identical oscillations.



> Is it possible the reading we're being shown is an instantaneous sample of a PWM control signal? It would account for "random" values being shown when less-than-full output is called for.


It is possible that the ECM can't make any soup (Dutch expression) of this PWM signal, while the PWM control signal itself might look perfect. (when viewed with an oscilloscope). I just have no possibility to reach the DFM right now. 



> (you and all your nice Euro-only options! ). That implies that you park outside. You might consider a solar charger semi-permanently installed on the hat shelf. The W12 reflective glass will cut down on output, but it'll be better than nothing. Or, tweak your solar sunroof wiring a bit.


Do I detect some Euro jealousy here?  A solar panel won't help me through our dark and windy winters though... Perhaps a wind turbine would be a better idea? :laugh: 


Willem


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## Paximus (Aug 26, 2011)

> what I really need is something that can top off the battery while driving
> ...
> Perhaps a wind turbine would be a better idea?


You answered your own question! 











I already have a worry about units 50 & 52 - the controllers!

CB


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## PanEuropean (Nov 3, 2001)

WillemBal said:


> How many batteries did you already replace since it was new? Mine was replaced with an original battery in June, 2009. And the battery itself was manufactured in 2009 as well. Is it time for a new battery already?


Hi Willem:

My car was manufactured in September of 2003 (it is a MY 2004 car). I took delivery of it, new, with 3 km on it, in the fall of 2004. My VW dealer put a new left battery in it as part of the PDI, because he was concerned that during the half-year that the car was in the showroom, the battery had been run down too often.

I used that LH battery (manufactured Q1 2004) until the summer of 2011, when I replaced it with a new one. So, I think that it is reasonable to expect between 5 years (minimum) and 7 years (maximum without having to worry about the battery failing on the first cold day of the year) out of the left battery.

I suspect you will get close to 7 years out of yours, first because the climate in your community is mild, and second because you maintain it on a regular basis with the external charger.

FYI I still have my original starter battery, which tested just perfectly last summer at the VW dealership using the VW battery testing tool. I am quite surprised at the longevity of the RH battery, but I suppose it really does not get used all that often (just for engine cranking), therefore it has a pretty soft life.

Michael


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## WillemBal (Nov 20, 2010)

PanEuropean said:


> I am quite surprised at the longevity of the RH battery, but I suppose it really does not get used all that often (just for engine cranking), therefore it has a pretty soft life.


Hi Michael,
Indeed the RH battery tested perfectly today at the dealer. And in fact, the LH battery wasn't so bad either, compared to the result which was obtained back in August year. 

Below are the two results of the LH battery (2011 and now) and the RH battery.
FYI:
"Laadtoest" = "Laadtoestand" = *Charge condition*
"Gemeten" = *Measured value*
"Waarde" = *(reference/specified) value*
17/4/2012 = 17 April 2012
"Laden" = *Charge* (what I've been doing all winter just about every week )










Willem


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## WillemBal (Nov 20, 2010)

Paximus said:


> I already have a worry about units 50 & 52 - the controllers!


Brilliant! The car even has a spoiler! And unit 10 must be the solar panel, I presume?


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## WillemBal (Nov 20, 2010)

*Mike's V10 Phaeton*

Mike sent me some log files. Unfortunately there is some confusion (not only Mike ) about which group should be addressed to obtain the generator load value. Apparently, it is hidden in group 16 of the ECM. Also, the Phaeton Diesels seem to not yet have label file, or I couldn't find it.
Some more detailed information is given below:

Group 016 Additional heater / Zusatz Heizung (heater elements in cooling system)



*Generator loading*
Additional heater
Activation of heater elements
Voltage supply from ECM


Anyway, Mike's results are quite remarkable, at least when we compared them with the W12 version. Below are some trends of the V10:










So far, the trend is similar to the W12. The battery voltage drops considerably during the start procedure, then quite rapidly the generator starts functioning, raising the voltage to 13.4 to 13.5 Volts.

Next picture shows the trend of the "Load Voltage" during Mike's trip:










It is remarkable to see that the load % values are not "random", as they appear in the W12 logs. Just after start, the generator needs to work harder to increase the supply voltage back to a sufficiently high value. Once it is approaching the target value (explained below), it reduces the "load" value. This value is in fact the amount of correction as applied by the regulator.

Below is attempted to visualize the load versus RPM:










I won't say much about the factor R2, but basically it tells us something about how well one parameter is depending on the other. A value of zero means there is no relationship, a factor of 1 means it is perfect. The regression line describes the supposed linear regression and the R2 factor is pretty poor. Nevertheless, there is at least some relationship. This is related to the higher output of the generator at higher RPM. A good fit would probably be present when the load is kept constant, which is obviously not the case.

But the next trend shows a better relationship:










This is almost like to a text book example of a proportional control loop. In such a control loop, the control signal (the load % in this case) is proportional to the amount of deviation of a set point (desired value). The control signal will be zero when the set point has been reached. As you can see in the trend, this point can be found where the trend line crosses the X-axis (load% = 0).
The problem with a proportional control loop is that there is always a difference with the desired (14 Volt) value. This control loop will only do something when there is a difference, and when there is no difference, then no intervention is needed. More clever control loops also integrate the difference (i.e. add more control signal when the difference stays constant) or try to anticipate the amount of control signal when a sudden change occurs (differentiating action). For those of you who want to know more about this, please google "PID control loop".

Bottom line is that the load % value is not a *measured *value, but a *control* signal. The more load on the battery, the lower the voltage will be. The lower the voltage, the more control signal needs to be applied (more field current for more magnetism in the poles). So this signal is a "kind of" load signal. Almost "Simple comme bonjour" as the French say. 

Willem


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## WillemBal (Nov 20, 2010)

*Mike's V6*

Mike's V6 seems to provide a much higher voltage: 










14.4 Volts!

Mike, you are the winner! :wave:


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## WillemBal (Nov 20, 2010)

*Jason's W12*

Here are Jason's trends:










Markers are placed where the dash panel meter indicated exactly 14 Volts. Quite a difference with the 12.82 Volts, as recorded by the VCDS.
Jason placed a marker at a point roughly 3-5 seconds after voltage stabilized at 14V indicated by the panel meter.
The second marker is where he added headlights, foglights, seat heater and music playing to add some electrical load. Indicated voltage stayed at 14V the entire time during driving. Difference with the VCDS is about 0.5 Volts.

The next, blue snow picture, trends the load % during his trip:










The load % versus Voltage trend seems to be typical for the W12, as shown in the picture below. 










Well, I hope you are still with me now... Lots of trends and puzzling information.
Looking forward to comments...

Willem


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## jyoung8607 (Feb 14, 2006)

Willem,

Very interesting stuff.

I have several thoughts on your earlier postings, but I'd like to explore an idea first: do you really have a problem?

While running, your ECM-measured voltages don't seem to be out of line with mine and Michael's. You seem to draw your battery down with the aux heater, but that wouldn't be totally out of line if your trips are too short to replenish the battery.

Your Midtronics measured battery voltage of 12.1-12.2V when testing would reflect about 40-50% charged for an open-circuit resting battery. But, $5 says your tech didn't disconnect it from the car, and all sorts of stuff will be awake with the trunk open. A measurement under unknown load doesn't really reflect its state of charge. I'll take a measurement of mine later to compare.

This leaves your wandering dash panel voltmeter. My dash panel seems happy to indicate 14V on the dot for anything roughly 13.0V and above that I've seen, and you say you're getting up into that range - although it would be worth using VCDS to check the dash panel itself rather than the ECM. Do you have a full-car auto-scan you can email me? I wonder if the dash panel voltmeter is not supposed to be stabilized for a car in your market, or if you did any custom recoding or it has odd firmware? VW does customize dash panel and other behavior by market. I know I'm grasping at straws (USA expression), but let's compare our controller part numbers and coding and such.

Jason


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## Paximus (Aug 26, 2011)

Mike's V6 TDI voltage seems to be reporting the normalised feed to the voltmeter rather than the Power Supply voltage.

Chris


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## WillemBal (Nov 20, 2010)

jyoung8607 said:


> ..... do you really have a problem?.....


I don't know, ask my wife and she'll probably say yes, but my shrink doesn't yet have a clue 

I've learnt to live with imperfections, i.e. I don't mind when my car occasionally doesn't crank at once, sometimes doesn't lock using the door handle buttons, occasionally doesn't open the trunk lid using the VW logo...
I know that all of these little inconveniences instantly disappear by shutting down the engine, leave it and come back. Or make a scan and clear all DTC's.
As far as the occasional crank imperfection is concerned:
During half a year, I had this happening about 1 or 2 times a month: car seems to crank normal for half a second, then dies, another push on the start button cranks the engine normally. Since last winter, I know that it must be due to a low battery charge condition (not a poor battery), because since I use the battery charger every week, this problem is vanished.
I know for sure that the dash panel meter indicates exactly the same as what is reported by VCDS, plus 0.25 Volts. When I switch off my rear PTC heaters via the A/C menu -> "Extra functions" page, the dash panel VM goes up by 0.4 Volt at any RPM above 1000. Rear windshield heater: 0.3 Volts and dipped beam (not city light): 0.25 Volts.
Sometimes, after making a night trip and after parking the car on my drive way, the interior lights start flickering (engine running idle at 550 RPM). When I see this (faint) flickering, I check my VM and at all occasions I see it drop down to 12 Volt. Increasing idle speed puts the needle back to 13.5 Volts. I release the gas pedal: voltage stays 13.5 Volts, no flickering.:screwy:

Some time ago, Wouter visited me and I of course was allowed to measure his battery voltage before and after start. From the top of my head, readings were 0.2 Volts higher (i.e. 12.5) before starting the engine and afterwards, the DVM rapidly indicated 14.2 to even 14.4 Volts. I never see these voltages, even not immediately after recharging the battery overnight. Charger is fine...please be sure I checked the voltage several times.
This triggered my R&D heart to search for possible causes of the problem - and remedies.

Perhaps all this is caused by the high energy consuming W12 engines... which would be food for the thought that the generator the Achilles heel of the W12 Phaeton.



> While running, your ECM-measured voltages don't seem to be out of line with mine and Michael's. You seem to draw your battery down with the aux heater, but that wouldn't be totally out of line if your trips are too short to replenish the battery.[QUOTE/]
> 
> It actually doesn't matter whether I make 5 km or 500 km trips.
> 
> ...


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## n968412L (Apr 23, 2009)

Paximus said:


> Mike's V6 TDI voltage seems to be reporting the normalised feed to the voltmeter rather than the Power Supply voltage.
> 
> Chris


Hi Chris - I think that assumes that the panel voltmeter really is a voltmeter... I bet it's not! 

Not pondered all Willem's trends yet.... all jolly confusing!

M


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## Paximus (Aug 26, 2011)

> I think that assumes that the panel voltmeter really is a voltmeter... I bet it's not!


 Ahh, what in this life is what it seems? The news is all spin-doctored, photos are all airbrushed, reality is virtual, and voltmeters are pulse-width modulated energy-to-angular-rotation converters!  

Chris


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## WillemBal (Nov 20, 2010)

Paximus said:


> Ahh, what in this life is what it seems? The news is all spin-doctored, photos are all airbrushed, reality is virtual, and voltmeters are pulse-width modulated energy-to-angular-rotation converters!
> 
> Chris


 Absolutely! For instance, when you take a look at your odometer, you will see that the scale is not linear, although at first glance there is nothing odd with it. The angle displacement of the needle is proportional to the speed up to 80 km/h, i.e. each +10 km/h causes the same positive angle displacement of the meter. From 80 km/h to 100 km/h causes the needle to rotate the same way as from 70 to 80. And above 200 km/h, each additional step is 30 km/h instead of 20 km/h. 
The result is that, while zero and 320 are neatly positioned at symmetrical positions with respect to the 100 km/h, which is then in the centre of the scale. Apparently, the digital information is converted/adapted to the scale of the odometer to make this all happen. 

Controller 17 (Instruments) contains various information which is presented in the instrument cluster. One piece of information, in group 004, seems to be the 004,1 Voltage at Instrument Cluster. The reported voltage is exactly the same as presented by the dash panel voltmeter. The resolution is 0.1 Volt, opposed to the resolution of the voltages as reported by the other controllers, i.e. the ECM, the Battery Monitor controller etc. (0.05 V) 
In VCDS, this group 004-1 voltage is clarified by the text "*generator voltage*". 
In my own car, the group 4 voltage is a little higher than the voltage as reported by the battery monitor and the ECM when the engine is running. When the ignition is on while the engine is off, this voltage is slightly lower than the battery voltage. In both cases (engine running and ignition on), the group 4 voltage of the instrument cluster is identical to the dash panel meter reading. 

After I recharged the battery overnight, I got readings near 14 Volts (Controller 17, group 4). Dash VM's needle solidly on 14 Volts during 5 minutes of driving with all electrical consumers off. 
As soon as I switched on A/C and the rear heater, the voltage dropped to 13.5 Volts. 

Willem


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## Paximus (Aug 26, 2011)

Hi Willem, 

Just for interest, what is the VCDS scan text on your Address 17: Instruments (Combi Instrument)? 

Chris


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## WillemBal (Nov 20, 2010)

As you know, I originally started this thread to be able to diagnose the electrical system using tools which we have. VCDS seemed a perfect tool for this purpose, however up till now, more questions arose than were answered. One question is answered though, and this relates to the way the generator recharges the battery while driving. The charging process doesn't seem to be different from any other car (as far as the LH-convience battery is concerned). The generator is tightly connected to the battery - the only difference is that there is about 6 meters of 50 sq. mm cable between generator and battery. 
The output of a our generator is controlled by an internal regulator, which in turn is only controlled by the output voltage itself. It tries to maintain the output to 14.2 to 14.4 Volts (the float charge voltage) and any deviation from this setting is corrected by the regulator, which in turn increases the DF (dynamo field) current. Only when the electrical load is very high, this voltage may not be maintained. This may happen when the engine is running idle (stationary) at for instance 550 RPM. To overcome this situation, the Central Electrical Controller sends a signal to the ECM, to increase the RPM to 650 RPM (in the case of a W12). 

This is all perfectly understandable, but still, the charging system isn't different from a car produced in the 80's. What is different though, is the way how it is discharged. For instance, the 30+ computers already awake when someone touches the door handle, not to mention when one unlocks the door or even the trunk lid. Massive power consumption of all controllers, randomly taking energy from the battery, prevents proper battery diagnosis. And despite the use of "smart" diagnostic tools, mixed with whatever intelligence the technician (unintentionally) might throw in the game, I think that the battery/generator is best determined by means of good old proven tools, like volt and amp meters, possibly complemented by more advanced tools, such as oscilloscopes. 

The most simple tests, still performed by many car technicians, are the OCV test and the alternator output test. The first test is almost impossible to perform on the Phaeton, because the trunk lid needs to be opened, causing immediate and hefty drain of the LH battery. In my opinion, I found a better location to perform this test, which is right under the bonnet, next to the jump start post. 

All you need to for this test is to purchase a 20 $ DMM and all you need to do is to lift one little panel under the hood, and lift a red cap, covering two major electrical junctions: 










These 2 junctions are connecting multiple major electrical components. 
The left one (seen from the front of the car) is also called the jump-start post. Connected to the starter AND to the starter battery. 
The right one is the "TV22" junction. There is just one meter of 75 sq.mm wire between this junction and the generator. The aft side of this junction (not visible on this photo) connects directly to the battery via a 50 sq. mm wire. 

The procedure to test OCV and alternator voltage is pretty simple. 



When you plan to do this test, pull the handle for opening the bonnet prior to leaving and locking the car. 

Wait at least 10 minutes (to allow out-run of processes like coolant fans and pumps). 

Find paper and pen to make notes of all the readings. 

Now open the bonnet and connect your DMM (selector set to DC Voltage) as per below photo. 

This is the OCV (open cell voltage). Above 12.6 Volts indicates >90% charged (12.8 is fully charged). 

Now enter your car (bonnet still open), do NOT start the car, but switch on ignition. Your dash panel will now light up all warning lights, as usual. 

Turn A/C all the way to the left (0). This will shut it down completely. 

Observe the dash panel voltmeter: it will read between 12 and 12.5 Volts. 

Now, again measure the same TV22 junction voltage with the DMM. It will probably read approximately 0.2 to 0.3 Volts lower. 

Start the engine. 

Observe the dash panel meter. It will first drop a bit, then hesitantly climb to 14 Volts within 10 seconds. 

Now, again measure the same TV22 junction voltage with the DMM. It should at least read 14.0 Volts. 

 

My own set-up looked like as in the photo below: 










Above is the OCV (open cell voltage) which looks OK to me. I would have liked to see 12.8 Volts, since I had recharged the battery the night before, but I still was happy to see that this voltage was 0.3 Volts more than what the dealer had measured with his intelligent Midtronic device at the battery in the trunk. 
For 80's cars, the alternator voltage is usually between 14.2 and 14.4 Volts. I measured 14.01 Volts with A/C off and 13.7 with A/C on. In my case, the rear heater (PTC's) draw a considerable amount of current. I guess that the engine itself already is demanding a lot of electrical energy. 

Of course, you may wish to inspect the starter battery as well. Below is my "OCV" reading. 










In this case, it is much higher than 12.8 Volts. The reason is that a trustworthy OCV reading can only be obtained when the battery is slightly discharged prior to taking the reading. An OCV reading of higher than 12.8 Volts indicates that the battery was fully charged, but never loaded after charging and is perfectly normal. Any reading between 12.8 and 14.2 Volts can be expected. 

Willem


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## WillemBal (Nov 20, 2010)

Paximus said:


> Hi Willem,
> Just for interest, what is the VCDS scan text on your Address 17: Instruments (Combi Instrument)?


 Hi Chris, 

My last scan, made just shortly after my dash panel meter (possibly also the odometer) was completely dead, showed this result: 

Address 17: Instruments Labels: 3D0-920-xxx-17.lbl 
Part No: 3D0 920 881 E 
Component: KOMBIINSTRUMENT RB4 0321 
Coding: 0005111 
Shop #: WSC 00420 211 102108 
VCID: 2854FAFEA4A90D5C 

1 Fault Found 
00457 - Control Module for Network (J519) 
004 - No Signal/Communication - Intermittent 

Does it trigger a "Eureka" moment?  

Willem


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## EnglishPhaeton (Dec 6, 2010)

:screwy::what::thumbdown::facepalm::laugh::laugh::banghead: 

OH MY GOD, I think I'll buy a FIAT.................................... 

Stu


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## WillemBal (Nov 20, 2010)

EnglishPhaeton said:


> :screwy::what::thumbdown::facepalm::laugh::laugh::banghead:
> OH MY GOD, I think I'll buy a FIAT....................................
> Stu


 :laugh::laugh::laugh: 
Hi Stu, 
Don't forget to watch this *Instruction Video* before you buy one...


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## EnglishPhaeton (Dec 6, 2010)

WillemBal said:


> :laugh::laugh::laugh:
> Hi Stu,
> Don't forget to watch this *Instruction Video* before you buy one...


 So Willem, 

is this the problem that you have with your Phaeton? If so I suggest a much longer piece of string to start her up on a morning! 

:laugh::laugh::laugh: 

Stu


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## Paximus (Aug 26, 2011)

> Willem: My last scan... Does it trigger a "Eureka" moment?


 Alas no, I was idly seeing of there was some possible reason why your coding would make your dash voltmeter read the true voltage all the time, instead of normalising at 14V like everyone else's. 

But your software version is functionality 21, same as mine. 

The hardware is different (you have 3D0 920 881 E and I have 3D0 920 982), but the coding is the same except for EU v UK settings. 

Conclusion: your Vehicle Power Supply is usually running at a voltage just below the 'normalisation' value that makes the dash voltmeter jump to 14.0V, probably 13.55V 


Chris


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## jyoung8607 (Feb 14, 2006)

Willem, 

I have been thinking about the additional data you posted. I don't have anything really conclusive to say, but evidence leans toward your alternator being broken. 

Interesting facts you've posted: 

* It appears that fully charging your VPS battery and starting the car without load takes your dash panel voltmeter into the 14.0V-indicated normalized range. Then, adding a very normal and reasonable amount of load takes you out of the normalized range, which doesn't happen for anyone else. 

* It appears that your VPS battery isn't getting fully charged. This could be a bad alternator. Or, your alternator could be fine and your low-voltage readings could be due to excessive load trying to charge up your near-flat VPS battery. I lean toward the first because you can create pretty deep voltage sags with reasonable load and a fully-charged VPS battery. 

* On the scans you sent me, you say your dash panel voltmeter was stuck at zero during one of the scans. It also shows communication faults with the J519 central electronics controller. That implies the dash panel doesn't monitor voltage itself, but displays a value measured (or relayed) by J519 and transmitted via CAN. 

* I was aware of the jump-start terminal, of course, but I wasn't aware of the TV22 terminal right there next to it. That seems like a very odd design and placement. It seems like it would be very easily to accidentally short/bridge the two halves of your electrical system together when clamping on a jump-start cable, and no purpose I can think of for it to be there. I am going to check wiring diagrams and read up on that. I wonder if there were originally plans to allow deliberate/emergency bridging or direct powering of the VPS electrical system from there. 

I read somewhere the vehicle system-voltage measurement point is on the "main" fuse panel that ties together the alternator and the main terminal 15/terminal 30 feeds and such, in the trunk near the convenience battery. 

I'm a couple thousand miles away from my Phaeton this week. But, when I get back home this weekend I will make a chart of voltages seen in VCDS polling the dash panel as compared to voltages indicated on the physical voltmeter. Once we have a known reference model for how the physical voltmeter works, and we know the 14.0V-normalized display range, we can ask some other people to verify it on their cars. Then we can finally figure out whether it's your voltmeter misbehaving or your alternator misbehaving. 

Jason


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## WillemBal (Nov 20, 2010)

jyoung8607 said:


> * It appears that fully charging your VPS battery and starting the car without load takes your dash panel voltmeter into the 14.0V-indicated normalized range. Then, adding a very normal and reasonable amount of load takes you out of the normalized range, which doesn't happen for anyone else.


 Hi Jason, 
Since I know that my rear PTC heaters consume a lot of energy, I now have made it a habit to first disable the rear A/C right after starting the engine. Then the DP voltmeter climbs to 13.5. Else, without disabling the rear A/C, the DPV does not come higher than 13 and a bit. At any RPM, switching on the rear A/C results in dropping of the DP voltage with about 0.3 to 0.5 Volt. 



> * It appears that your VPS battery isn't getting fully charged. This could be a bad alternator.


 I think so too. 



> Or, your alternator could be fine and your low-voltage readings could be due to excessive load trying to charge up your near-flat VPS battery. I lean toward the first because ...


 I think so to (the first) but that is because I measured the current going in and out of the battery some time ago. The resulting charge current is often zero and sometimes negative. I will post some oscilloscope screens demonstrating this. I'm sure that Stu can't wait to see these. 



> * On the scans you sent me, you say your dash panel voltmeter was stuck at zero during one of the scans. It also shows communication faults with the J519 central electronics controller. That implies the dash panel doesn't monitor voltage itself, but displays a value measured (or relayed) by J519 and transmitted via CAN.
> 
> 
> > Although the scan was made after when the car functioned normal again, I agree with your conclusion that the implication is that the DPV might be measured by J519. It reports via the K-Can and some other controllers, also using K-CAN, also complained about J1519. (threw the same DTC)
> ...


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## WillemBal (Nov 20, 2010)

Some time ago, I made some measurements using an oscilloscope with voltage probes and an AC/DC current clamp. I did not yet post them, in order to see whether it would be possible to diagnose alternator problems with more common tools. At this stage, these oscilloscope measurements may shed some additional light on what is happening. 

My first set-up is in the trunk: 










On the photo, you can see the oscilloscope, the current clamp, capable of measuring the current from -40 to +40 Amps, and an additional voltage probe (hardly visible). 
The oscilloscope "reads" as a strip chart recorder. The horizontal scale represents the time, the vertical scale (Y-axis) the voltage or current. 

The scope has two channels and for the sake of easy identification, they are colored. 
Yellow/Orange for channel 1 and Blue for Channel two. 

Below is the first measurement, which is cryptically called a "SCAN". I set the time base to 5 seconds (per division), which implies that the total horizontal scale covers a time period of 50 seconds. 









Further explanation is necessary to fully understand what we are seeing. 
At the left hand side of the screen, you can see two little arrows, marked 1-> and 2->. 
1-> indicates the zero for channel 1, which is connected to the voltage probe and battery +. This implies that zero volts on the channel 1 would be indicated as a horizontal (orange) line at the bottom of the screen. 
2-> indicates that zero is at the top side of the screen. Therefore, we will only be able to see negative values (discharging of the battery). 

Just below the X-axis, some text clarifies the vertical deflection values and the horizontal scale. 
CH1 2.00 V indicates that each vertical division represents 2 Volts. 
Because the yellow trace sits at near 6.3 divisions, the voltage during this scan was near 12.6 Volts. 
A little correction of -0.2 Volts is necessary, due to a -1.5% error of the probe. 
CH2 1A indicates that each vertical division represents 1 Amp, as far as the blue trace is concerned. 

The picture shows what happened when I closed the trunk lid. Just prior to closing, the scan started (left hand side). The current then was -3.5 Amps (the blue trace starts at -3.5 divisions from the top). After 9 seconds, (almost 2 divisions from the left), I pressed the close button. The blue trace drops off scale, indicating that the current briefly was lower than -10 Amps. 
After the trunk lid closed, the current draw reduces step wise, probably because controllers are switched off one by one. 
After 50 seconds, the negative (discharge current) is still -3.5 Amps. It can take up to 10 minutes before the current finally is near zero (normally around 35 milliAmps). 

In the next post, I'm going to start the engine and see what happens. 

Willem


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## Paximus (Aug 26, 2011)

OK - so far so good! - Chris


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## WillemBal (Nov 20, 2010)

*Crancking the engine*



Paximus said:


> OK - so far so good! - Chris


 Ahhh, thanks Chris, it is good to see there is live audience! :thumbup: 

During the next scan, I open my trunk lid, and shortly thereafter entered the car, followed by ignition and starting of the engine. 










I changed the vertical scale of channel 2 to 10 Amps/div and put the zero in the centre - to be able to see both charging and discharging of the battery. 

Opening the trunk lid makes the current meter "clip to" -40 Amps. And soon after starting the engine (roughly 20 seconds after starting the scan), you can see that the charge current clips at +40 Amps. The average charge current, as far as it can be seen in the "noisy" part of the picture, begins at about 35 Amps (20 seconds from start scan). 

The voltage, represented by the yellow line, follows a trend as I would expect (in contrast to the heavily varying charge current). 
In the next post, more about this current. 

Willem


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## Paximus (Aug 26, 2011)

So at 35 secs from start of recording, given that the scope CH1 shows a -0.2V baseline offset, the scope probe is seeing 13.4V? You mentioned a correction factor on that.


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## WillemBal (Nov 20, 2010)

*Shortly after starting the engine*

During the first minute, the RPM stays around 900 to 1000 RPM. Below scan is made during this minute. 










I changed the time base to 25 ms, so the total time is 0.25 seconds. Also the vertical scale of the current meter is adapted, it is now set to 10 Amps per division. 

The right hand side of the screen shows some automatic measurements. In this case, the following can be read: 


The battery voltage stabilizes at 13.7 Volts (13.9 -.2 correction). 

The "ripple" on the battery voltage is 320 mV, which I consider as good, given the very high peak-to-peak charge/discharge current (62.8 Amps). 

The mean current is 7.04 Amps, meaning that the battery is actually charged with a mean current of 7.04 Amps. 

 
But the battery has a hard life. It has to swallow large current peaks as you can see.:screwy: 
I guess that you this surprises everyone, including me. 

It is difficult to determine where these large peaks are originated. It could be a screwy alternator, or may be caused by a periodic consumption of one of the controllers. 
The alternator makes about 3 times more RPM more than the crank shaft. (gear ratio of 1:3 based on pulley diameters). So with 900 RPM, the alternator RPM is 2700 RPM. Each revolution of the alternator therefore takes 22 ms (milli seconds). That is almost 1 division. Can you see any relation with what is shown? 

Next, I will change the RPM of the engine and change the load, by switching on some consumers. 
Willem


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## WillemBal (Nov 20, 2010)

Paximus said:


> So at 35 secs from start of recording, given that the scope CH1 shows a -0.2V baseline offset, the scope probe is seeing 13.4V? You mentioned a correction factor on that.


 Correctly observed. The trace at 7 divisions from the left sits at 6.8 divisions (difficult to see as the CH2 trace is blurring CH1 trace), so voltage is 2x6.8 minus 0.2 Volts correction. 

Below is a picture I took when the engine idled at 550 RPM and with lights switched on. 










I moved channel 1 (battery voltage) to the lower side of the screen, to get a better view of the current. 
The ripple you see (about 16 ms period) is not the diode ripple. If you look carefully, you can find more recurring artefacts. They may be related to anything that consumes power on a repetitive basis. For instance, at this RPM, every 18 ms an injector is energized. I doubt, however, that injectors have a peak power consumption of 66.4 Amps. 
The "diode ripple" now becomes faintly visible at the "flats" of the positive peaks. 
I have some good pictures of this ripple as well. 

Willem


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## Paximus (Aug 26, 2011)

I guess 16ms could be the headlights, 62Hz current gulps seems about right for flicker...


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## WillemBal (Nov 20, 2010)

I don't know... The difference between the last two pictures is that the last one was taken with the lights were on and the time base was expanded to 10 ms/Div versus 25 ms/Div. 
And the mean current (the net charging current) drops from 7 to 2 Amps, while the voltage drops from 13.7 to 13.5 V(corrected). 

Willem


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## jyoung8607 (Feb 14, 2006)

I have a feeling, before this thread is over, Willem will be adding a roof windmill or a small fission reactor. :laugh: 

In seriousness, I wonder how your readings compare with some known alternator fault conditions described in references from Mercedes and Ford. Lessons from these should be adaptable IF we know enough about the internal design of the W12 alternator. 

Jason


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## WillemBal (Nov 20, 2010)

jyoung8607 said:


> I have a feeling, before this thread is over, Willem will be adding a roof windmill or a small fission reactor. :laugh:


  


> In seriousness, I wonder how your readings compare with some known alternator fault conditions described in references from ....Lessons from these should be adaptable IF we know enough about the internal design of the W12 alternator.


 Thanks for posting these links. I already had read these documents, including a dozen others.  
It seems that all alternators are manufactured by a just a couple of manufacturers, like Bosch, Hitachi and Delco-Remy (now Delphi). Some additional stuff to read here: 
Delco-Remy Learning Guide. 

As far as I know, our alternator has two delta rotors, with 12 diodes. The rotor has 6 pole-pairs (12 poles) and according to the theory, the stator would have 72 segments, good for 72 ripples per revolution. Since the alternator makes 3x more revs than the crank shaft (estimation), the ripple frequency would be about 1980 Hz, and the ripple period would then be *505 ns*. (0.5 ms). 
What we can learn from your document, we would be looking for at least 12 uninterrupted ripples to come to the conclusion that our alternator is functioning well. The periodic time of 12 ripples is *6 ms*. 

Below is one of the last pictures I made in the trunk. It is made at 1500 RPM, so all periodic times related to the generator should then be much smaller. 








. 

The periodic drop of the charge current still is 16 ms, so I guess we can conclude that this is not related to any rotating part of the car. Also interesting is that apparently only the net charge current and voltage increased a bit. 

For a better view of the voltage ripple, I moved my gear to under the hood.... 

Willem


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## jyoung8607 (Feb 14, 2006)

WillemBal said:


> For a better view of the voltage ripple, I moved my gear to under the hood....


 If you haven't already, you might disconnect the smoothing capacitor while you're taking measurements. The reason it exists is to hide or dampen voltage ripple from the alternator, and that's the very effect you're trying to analyze.


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## WillemBal (Nov 20, 2010)

*Under the hood measurements*



jyoung8607 said:


> If you haven't already, you might disconnect the smoothing capacitor while you're taking measurements. The reason it exists is to hide or dampen voltage ripple from the alternator, and that's the very effect you're trying to analyze.


 Hi Jason, 
I considered doing so, but on the other hand, this capacitor is not a "super" capacitor. Its capacitance would need to be in the multi-Farad range to somewhat reduce the diode ripple of the alternator. I have a feeling that this capacitor sits there to reduce RF noise and spikes, generated by the alternator, the ECM etc. I will show some pictures, demonstrating all sorts of noise later on. 

I hooked up two voltage probes on the TV2 and TV22 junction. The TV2 junction gives the starter battery voltage and the TV22 junction is just one meter away from the generator. And connected to the LH battery in the trunk. 

Below picture was made while I started the car. 










The orange trace is about the LH battery; the blue trace represents the RH starter battery. With the -0.2 Volt correction in mind, the RH battery quickly resumes a voltage near 15 Volts and the generator outputs almost 14 Volts. 

Then later on, it stabilizes near 14.3 Volts: 










Now, with channel 1 on AC coupling (DC decoupled), it is possible to get a better view of the ripple. Engine RPM = 550.: 










And throttling the engine up to 1500 RPM flat (don't ask me how I did that) 










Although this picture already resembles a text book ripple, there is something puzzling about it. The period of the ripple is about 350 μs (microseconds). That is about double the amount that I would expect. Possibly, this is indicating that one delta winding is completely missing or all diodes of one set of stator windings are all open. Then the alternator now effectively has become a 3-phase alternator instead of 6 phase one. The problem here is that we do not know all engineering details, i.e. the gear ratio of crankshaft to alternator rotor may be lower than 1:3, or phases have been paralleled, etc. 
Also interesting are the spikes. I guess this is the type of spike that is supposed to be dampened by the capacitor. Without it, these spikes would probably much higher. 

Some more interesting pictures in my next post.


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## WillemBal (Nov 20, 2010)

*More under the hood*

More pictures... 
I now moved my channel 2 probe to the same TV22 junction. This allows us to see both the DC voltage value and the ripple. All measurements in the right hand side of the screen thus refer to the alternator voltage. 

At 550 RPM with all electrical consumers shut off: 










Besides some weird spikes, this ripple pattern looks OK to me. The ripple voltage is just 100 mVpp (half a division). The theoretical ripple of a 6 phase, double rectified generator is 400 mVpp... 

Now, after switching on the HVAC (including rear heater) plus lights: 








. 

Besides those two recurring "dips" in the ripple pattern, the drop in DC voltage is noteworthy. The diode ripple itself now increases a bit, to almost one division (200 mVpp). 

Shortly after taking and while storing this picture, the DC voltage must have dropped a bit further, as suddenly the RPM was automatically increased to 650 RPM, thanks to load intervention: 










That helped raising the voltage to 13.7 Volts. In the trunk, the voltage is 13.5 Volts, due to a 0.2 Volts drop in the power line (seems OK). 

And, a little later after I switched of all those nasty electrical consumers, the alternator was happily sitting at near 14 Volts again (still with 650 RPM): 










Later, at 550 RPM, with all possible lights plus heater on: 










I wonder what we can conclude from these pictures... Is it really true that the engine needs to be dropped to replace/repair the alternator? :facepalm: 

Willem


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## n968412L (Apr 23, 2009)

I think I'm following this... 

Willem - you seem to be lookign for ripple related to the individual peaks of the phase voltages (which if it is a two delta winding machine, I think will therefore be six phase, not three phase - although I wouldn't rule it out - it depends on the physical relationship between rotor poles and stator windings). But I think that the ripple you're seeing on the scope might be the hysterisis in the voltage control, ie the rotor field winding control circuit effect? 

I actually think you're in the territory here that is beyond even most vehicle electricians. But that's not to say we can't eventually understand it. But that would probably be helped enormously by the ability to swap out some components... which is precisley what we don't want to do! 

I no longer have easy access to a scope or I'd repeat these measurements on my motors. I'll ask around colleagues at work and see if I can find one to borrow. 

Fascinating!!


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## WillemBal (Nov 20, 2010)

n968412L said:


> Willem - you seem to be lookign for ripple related to the individual peaks of the phase voltages (which if it is a two delta winding machine, I think will therefore be six phase, not three phase - although I wouldn't rule it out -


 Hi Mike, 
With two delta windings, there are indeed 6 phases. I was speculating that one delta would be missing completely, which results in only 3 phases left. 



> it depends on the physical relationship between rotor poles and stator windings


 When there are 6 pole pairs, then the angle displacement will be 60⁰. When the rotor has rotated 60⁰, each phase will have completed one period. For only one phase, you only need two stator segments. For 6 phases, you will need 6x2=12 stator segments. So for one complete revolution of 360⁰, 6 times that amount of segments are needed, so 72 segments. 
My ripple calculation was based on revolutions per second (of the crankshaft) times the gear ratio (crankshaft pulley diameter divided by alternator pulley diameter) times 72. Makes a ripple frequency of about 2000 Hz at 550 RPM. I can only see half that frequency in all screens. 



> But I think that the ripple you're seeing on the scope might be the hysterisis in the voltage control, ie the rotor field winding control circuit effect?


 I think that the answer to your question can be found in TB 27-05-04, the one which Michael posted earlier in this thread. 
On page 16, an oscilloscope screen is given as measured on the DFM (Dynamo Field Monitor) terminal on the alternator. It is the one which I did not yet monitor with my oscilloscope, because it is rather hard to reach. 
You can see the PWM signal (a bunch of spikes), which are spaced apart 2.8 ms approximately. 
(Horizontal scale is 5 ms/Div). Just below the scope screen, you see some values which seem to be originated by group 53 of the ECM: Real RPM, Specified RPM, Voltage, Generator Load %. 
I assume that the reported value of 99.2% implies the percentage of time that the field is activated (and the DFM voltage is zero). Then the remaining 0.8% (represented by the spikes you see) is just 22 μs (microseconds). I think that 22 μs is too short of time to be traced back in one of the oscilloscope screens. And at any RPM between 550 and 1500, the ripple period is much smaller than the 2.8 ms period of the DFM signal. 

Ironically, I just noticed that the load% is indicating 99.2%, which is a percentage which seems to dominate in three logs from three different cars: Michael's, Jason's and my own car. The specified RPM of 700 /min gives me the impression that ILM increased the RPM of the car (from 550 RPM if this is a W12). Still, the voltage is only 13.370 Volts, probably due to lots of switched on electrical consumers to obtain this picture. So perhaps the alternator is working as designed.  



> I actually think you're in the territory here that is beyond even most vehicle electricians.


 That is where the fun starts, at least for me. 



> But that's not to say we can't eventually understand it. But that would probably be helped enormously by the ability to swap out some components... which is precisely what we don't want to do!


 If I had spent the time on my work, I probably could have asked to dealer to swap the alternator several times. It is just more fun this way. 



> I no longer have easy access to a scope or I'd repeat these measurements on my motors. I'll ask around colleagues at work and see if I can find one to borrow.


 That would be great! Looking forward to see some screen shots. 

Willem


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## PanEuropean (Nov 3, 2001)

WillemBal said:


> I've learnt to live with imperfections, i.e. I don't mind when my car occasionally doesn't crank at once, sometimes doesn't lock using the door handle buttons, occasionally doesn't open the trunk lid using the VW logo...


 Hi Willem: 

I have been offline for a couple of weeks (ferried an aircraft across the Arctic into Libya - not much internet connectivity in either of those places), and just noticed your comment above. 

If it gives you any peace of mind, my car has always occasionally 'missed the cue' when I press the door lock button or touch the door handle, and has always occasionally needed a couple of pushes on the trunk lid button to open the trunk. I think that these little glitches relate to a design deficiency in the keyless access antenna system. The Phaeton had one of the very first generations of keyless access - it was pretty revolutionary at the time, but not exactly bulletproof. 

I have never had any problems with the car starting on the 'first push' of the start button, though. 

Have a look at the software version of your access and start controller (controller 7). The original issue ones were version 6400, later, a version 6700 controller was released. The most noticeable difference between the two versions is the requirement to depress and hold the brake pedal before the start button will function. This is a child safety initiative. 

Michael


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## WillemBal (Nov 20, 2010)

PanEuropean said:


> I have never had any problems with the car starting on the 'first push' of the start button, though....Have a look at the software version of your access and start controller (controller 7). The original issue ones were version 6400, later, a version 6700 controller was released. *The most noticeable difference between the two versions is the requirement to depress and hold the brake pedal before the start button will function*. This is a child safety initiative.


Hi Michael,
Thanks as always. 
My KESSY controller version is 6400 and indeed *does* things a little different. For instance, I can *stop* the engine without my foot on the brake pedal. And also, I can *stop* the engine with the gear selector lever in any other position than PARK, as long as I have my foot on the brake pedal. Then, after stopping the engine this way, the instrument cluster returns a message: "Please move selector to park".

Also noticeable is that when I lift my foot from the brake pedal just after the starter motor is engaged, but before the engine is fully running, the engine just dies instantly. So I have to put my foot on the brake pedal and keep it there until the engine is running. Pressing the starter button is only necessary for a brief moment. I love it this way, so I think I might as well stick to version 6400.

Willem


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## n968412L (Apr 23, 2009)

Hi Willem - just seen this clip on youtube http://www.youtube.com/watch?v=pEbu-2tlAps and I thought you'd be interested in the voltmeter.....

Regards

M


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## WillemBal (Nov 20, 2010)

Wow, I love the engine sound! I now always switch off the rear AC just after starting the engine, and that helps (when it is cold outside). Quite often, the needle now sticks to 14 V and sometimes drops a bit to 13.5V, so I'm happy with that. My feeling is that the W12 engine in particular, is a heavy electricity consumer. I was going to show another oscillogram which demonstrates the current surges caused by the igniter coils and the injectors, but some other activities distracted me.

Meanwhile, I used the VCDS to check the dials of the dash panel. Once the voltage is active in the self test sequence, it first goes to 16 Volts, then to 0 Volts, then to 14 Volts. So this confirms that the dial is using a digital input, probably coming from the Central Electronic Controller.

Willem


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## n968412L (Apr 23, 2009)

WillemBal said:


> Meanwhile, I used the VCDS to check the dials of the dash panel. Once the voltage is active in the self test sequence, it first goes to 16 Volts, then to 0 Volts, then to 14 Volts. So this confirms that the dial is using a digital input, probably coming from the Central Electronic Controller.


Good to have that confirmed.. I'd suspected this for a few months. As someone (might have been you) said sometime ago - it's a bit naughty feeding analogue instruments with digital input... at least if we're not told.

regards

M


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## Cobra91 (Jul 23, 2015)

*hi*

Hi man . I have a question... how did you made those photos? did the VCDS generated them? or you used some program?


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## Paximus (Aug 26, 2011)

> Hi man . I have a question... how did you made those photos? did the VCDS generated them? or you used some program?


Welcome to the forum!

Which pictures do you mean, that is, which post number and the person who posted them?

Chris


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## keveola (May 5, 2015)

*Perfect timing...*

for an old thread!

Just bought an old Sun Engine Analyzer 1115 to tinker with on some of our older cars. Other than testing electrical charging, I wonder if there is much else that can be checked on a Phaeton. Plugged it in and the scope powered-up!

I need to re-read the method for posting photos.


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## Paximus (Aug 26, 2011)

Hi Kevin (I presume!),

It is reckoned that the VWVortex servers don't have enough space to host images, which is fair enough for such a big forum. So we have to save our images on some other hosting service, usually free, and post the web link to the photo using the forum editor icon that looks like a painting of a tree in a picture frame. At least, that's what it is supposed to look like, it looks more like an open can of sardine fish to me.

The link that gets pasted into the editor pop-up window should look something like this: "http://www.photobucket.com/albums/ab275/MyLogon/diagnostics22.jpg" only without the quotes. This link is usually made available for copying from the image hosting site by clicking some kind of 'share' button next to the image. The hosted album should probably be set to _public_, to prevent obscure logon screens popping up when viewing forum posts.

I love old analogue testing equipment, it gives you a more intuitive and subtle sense of what is happening in many cases. But it can't read a CAN bus... 

Chris


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## Cobra91 (Jul 23, 2015)

**

WillemBal posted and is on #17


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## Bindaham (Apr 4, 2014)

My volt gauge is acting up intermittently as shown in the clip. It goes from 14V to 14.5 and close to 15. Never below 14.


[video]http://s1260.photobucket.com/user/bindaham/media/Mobile%20Uploads/9B181FCB-D11E-4DD3-829D-C777F536A9E7_zpshk4fp6jt.mp4.html[/video]


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## Paximus (Aug 26, 2011)

Hi Salah,

This is symptomatic of the left battery having an intermittent internal disconnection. It would be very unusual for the voltmeter itself to be faulty and over-read, but not impossible.

If the battery is (was) good and the voltage reading is genuine, then you can expect the batteries to overheat and suffer damage.

There could be other wiring or alternator defects, of course.

Chris


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## Bindaham (Apr 4, 2014)

Hello Chris,

Appreciate your take. I think I'm hearing a whine that may or may not be from the alternator. The over head lights flicker when that whine is there along with the gauge fluctuation but then stabilizes then do it again.

I wonder how many Phaeton alternators failed after 14 years of service!

The power supply battery is almost two years old, but with the summer heat that we're used to in Kuwait the trunk can be an oven. I also wonder if I can fit an auxiliary duct there to be used in the Summer time!

Regards,

Salah


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## Bindaham (Apr 4, 2014)

Just scanned and took this interesting MVB readings for the generator load :sly:


Revs 700 - * Load 0.0%* - 13.720V

Revs 1310 - *Load 0.0%* - 13.510V

Revs 2550 - *Load 0.0%* - 13.580V


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## invisiblewave (Sep 22, 2008)

I agree with Chris, it sounds like a faulty ground somewhere. In an amplified system with a weak power supply, you always get some sort of whine from the alternator exacerbated by a phase difference between ground points. Hopefully it is the alternator though, since a bad connection might be close to impossible to find!


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## Kuwaity (Apr 2, 2004)

Bindaham said:


> Hello Chris,
> 
> Appreciate your take. I think I'm hearing a whine that may or may not be from the alternator. The over head lights flicker when that whine is there along with the gauge fluctuation but then stabilizes then do it again.
> 
> ...



Bu Jarrah,


Try to rev engine to 2500 RPM and check the gauge / light flicker. Just guessing, it might be caused by the secondary air ejection pumps that draws high current (specially old ones that whines) during cold start when battery state of charge is low.


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## MofoG23 (May 22, 2004)

Bindaham said:


> My volt gauge is acting up intermittently as shown in the clip. It goes from 14V to 14.5 and close to 15. Never below 14.
> 
> 
> [video]http://s1260.photobucket.com/user/bindaham/media/Mobile%20Uploads/9B181FCB-D11E-4DD3-829D-C777F536A9E7_zpshk4fp6jt.mp4.html[/video]


Hi Salah - did you ever get this resolved? I have the same voltage fluctuations with my Touareg and see my interior dome lights pulse. 14 to 15 volts while driving or at idle.

I'm hoping its the alternator...


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## Bindaham (Apr 4, 2014)

I'm terrible sometimes in following posts addressed to me 

Thanks Ahmad for the tip. :thumbup:

Eric

Just saw your post after I replied to your dm. 

For everyone one else, the fluctuation does occasionally occur and a friend of mine who's a Porsche electrician checked the car and came to the conclusion that the gauge might be faulty! Batteries were both had good voltages. 

Regards,


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## Bindaham (Apr 4, 2014)

Kuwaity said:


> it might be caused by the secondary air ejection pumps that draws high current (specially old ones that whines) during cold start when battery state of charge is low.


Shouldn't that throw a code?


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## Kuwaity (Apr 2, 2004)

Bindaham said:


> Shouldn't that throw a code?


I didn't throw a CEL in my old VR5 Jetta when it became really jammed. Even after full malfunction, the CEL was not lit. 

I'm not sure about the fault codes since I didn't have VAG-COM. 


It happened few times in my Phaeton and there was no intermittent fault. 

These pumps draws high current, I can see a sudden dip I'm my S2000's interior lights on pump start up and slightly stronger light after pump stop.


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