Help Needed for Alternator Problems & Measurements Using VCDS

[WillemBal]

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.

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

[jyoung8607]

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

[PanEuropean]

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

[PanEuropean]

...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

[Paximus]

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
Field 3: Battery Voltage as seen by the Engine ECM
Field 4: Generator power in % (0 to 100)

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

[WillemBal]

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

[WillemBal]

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.

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

[WillemBal]

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

[n968412L]

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

[WillemBal]

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

[jyoung8607]

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.

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

[PanEuropean]

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

[n968412L]

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

[WillemBal]

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

[Paximus]

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

[WillemBal]

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

[WillemBal]

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

[Paximus]

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

[WillemBal]

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

[WillemBal]

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

[WillemBal]

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

[n968412L]

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

[Paximus]

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

[WillemBal]

... 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

[WillemBal]

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

[Paximus]

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

[WillemBal]

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

[PanEuropean]

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

[jyoung8607]

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.

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?

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.

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.

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

[jyoung8607]

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.

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

[WillemBal]

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?

.... 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?


Willem

[Paximus]

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

[PanEuropean]

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

[WillemBal]

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

[WillemBal]

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?