Gents,

Some nice data I can share.

After cleaning up the F32 prefuse box, I did the alternator heat soak test and electric power steering load test.
F32 tear down is here : https://mbworld.org/forums/e-class-w...ode-relay.html


The main log comes from Banks Gauge at 5Hz data points. It is 30.3 minutes long.
The secondary log is from Owon current clamp, reading alternator gross output, but i stop it at 23.3 minutes to save it from overheating, it is at the engine bay after all.

In between I done some videos.


The main log :



,




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The zero amps reading is the overloaded reading when above 105 AMPS, this current clamp is 100A max rated only.

The Banks Gauge log for B-BUS Voltage is also worth the same 23.3 minutes.
B-BUS voltage is from Rear SAM, the fuse box powering the OBD2 Port.


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First I want to add cooling fan power consumption data, as this is a big power sucker while in traffic jam where I idle in D a lot while braking and getting 540-550 RPM usually, very low RPM for alternator power.
12.5 amps is engine computers and whatever other modules while in engine OFF Ignition ON mode.





This is current log from OWON current clamp during cooling fan test.



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Voltage drop at alternator cable to F32 which is called MR8 terminal, to the Jumper terminal at 102 amps alternator load is 30 millivolts.
MR8 to Jumper terminal which is a B1 terminal too by parallel of main bus bar, means the current must pass thru V19 Q-Diode.



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How do I load up the alternator to above 100 amps ?
I can't use the Xentry to force the cooling fan to run maximum to generate extra 53 amps, as the OBD2 port is being used by Banks Gauge.

So I use these :

01. HVAC maximum blower speed.
02. Headlight High Beam and my Lazer Light Bar at approx 125 watts.
03. My 3 types of AUX light worth about 150ish watts
04. Rear windscreen heater/de-mister, worth about 20 amps
05. Alternator is still charging the battery at 10.x amps
06. Engine-Tranny in PARK, so idle is 610-650 RPM, engine was still cool at 60C.
07. Engine bay temperature ( underhood ) was still 45C only.






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The heat soak alternator be watched on video, photos are not good enough.
I also video the electrical power steering huge demand, while alternator is already heat soaked.


Legend




The video




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I could not get any data from Valeo or Bosch or any brand, except from Balmar marine alternator, the power de-rating of alternator once it is hot.
Too bad the definition of HOT is only 60C ambient air temperature inside a yacht engine room, while my car "engine room" can be as high as 90C plus.

Alternator only can produce its rated max amperage when it is at 3,000 RPM-Alternator.
My alternator pulley is think is 3 to 1 drive ratio, or 3x faster than engine.

However, at 550 RPM-Engine x 3 = 1650 RPM-Alternator only, the power output is not good enough for night time heat soak traffic jam creeping stop and go.
if ever cooling fan kick in at say 60% power ( not duty cycle , but power ) or approx 30 amps.... surely my battery will be in deficit.

If at 610 RPM-Engine = 1830 RPM-Alternator, the power output even when hot is decent.


When heat soaked





From Balmar
https://balmar.net/balmar-technology...output-curves/

It seems my Valeo 200A at 80C to 90C underhood temperature is behaving like Balmar 94 series 210 amps, not like the superb XT series 170amps


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MS! I'm glad to read you got your rollercoaster voltage well figured out.

Your additional auxiliary lights exceed ALT design limit for low idle load capacity.

You are proving ALT can not output 100A at 500.Rpm @ 14.15VDC. Actually it's probably a good thing because engine idle could stumble under high serpentine load...


Q2 drop makes batt a poor power supply!!

When load capacity is exceeded the system voltage drop and BATT is drained back out through F32 Q2-Diode.

You really-really don't want to surge your chassis fragile electronics with the dirty voltage spikes. It's in your best interest to prevent exceeding Maximum limits.

Besides we evidenced ECU ignition timing is impacted by poor voltage regulation. Meaning surging your chassis de-tunes engine most basic performance.

The 40+ on-board electronic computers use bare-bone filtering. I wonder what electronic assembly may first give you headaches... something that handles regulating significant power into a load :

1. Audio-Amp,
2. LED-HL,
3. Tank pump,
4. Steering-rack,
5. ECU injectors,
6. Engine cooling fan
7. ...

With normal chassis load we are well within limits near 85Amps @14.15V that is a nice 1200Watts already at idle. Base load is way less near 500Watts. All good.


There are many things you can do to reduce load below the ALT acceptable level:

1. No Rear defroster
2. No AUX HL + HighBeam + LowBeam
3. No Max A/C output
4. No hard steering
5. No drained out Batt

Don't let your load demand exceed Maximum limits at low 500.Rpm. To stay safe remain within the envelope.

+++ RIPPLES PACK ENERGY !!
Power riples are so hard to stop is because they pack a lot of energy force.


ripple factory... OMG
These go right through the power handling modules I enumerated above damaging their load side.

A 1.5V ripple on a 100A current is a 150Watts of power that needs to get dissipated somewhere somehow... Low ESR Capacitors get HOT doing it.

Ripples are to be avoided or minimized.
🤞

 

Those ripples are load test in progress at 60 amps - 105 amps. I really worked the alternator hard for this test

The normal electrical load at night in worst traffic jam and while not raining would be :
01. HVAC, blower at level 3-bar
02. Low beam headlight surely ON. No AUX light operated at all.
03. Very mild audio system volume, basically 2 amps worth at the most.
04. 550-RPM low due to tranny always in D braked but not HOLD.
Here the only sucker is Electric Power Steering when I change lane fast or is maneuvering in car parks.

Given the proof of EPS hungry power sucking, if logging is by Banks Gauge at 5hz, EPS effect towards 0.2 to 0.4 seconds voltage dip will be seen,
but Instrument Cluster will not see that as it is too slow or on purpose smoothed out. So only I can see such information, others don't.



COOL and 650 RPM in PARK. Respectable 100ish amps and voltage dip down to 13.6V ish only.





HOT and 535 RPM in D braked, starting to dip down below 13.7V B-BUS voltage while only at 47ish amps




It seems when heat soaked, 52 amps would be borderline MAX without dipping below 13.2V if at 540 RPM in D braked.


,




BELOW :
This is me parking the car, let go of the brake at idle speed and let car creep. No Amps data, logging of current stop at 1,400 seconds.
This is safe power output region RPM wise for alternator, even when being heat soaked. Releasing brake will creep the car and RPM up from 550 to 630 ish.
The mild voltage drop below 13.7 at B-BUS ( 1,806 and 1,808 second ) you see is the minor steering correction to straighten the car.





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I will need to log the HVAC power consumption like the cooling fan. It seems between 4-BAR to maximum 5-BAR the jump is high. I only will do blower full blast after parking car in hot sun and for like 5 minutes
after engine start So no headlight low beam to suck more power, when in day time.
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Anyway, the 550 RPM in D braked is a very nice elegant rock crawler kind of creeping speed in traffic jam....suitable for my city to self-roll with the slow traffic.
Sometime engine adjust to 600+ RPM in D while being braked... when car has done enough distance and engine has done its dumb-azz 105C coolant temp as thermal "politic".


The only possible constant power deficit while at 550 RPM in D braked at night+bad traffic scenario would be the cooling fan when and if it will kick into higher power mode above 350 watts.
This kind of high fan speed rarely happen in a moving-stop creeping traffic jam, except when engine kill happen for a few minutes while its hot and then I start the car again, where for like 2 minutes the fan
will kick in at easy 75% of power or more by sound of it.

At least now I know that my alternator COLD vs HOT is about 20 AMPS reduction at 550 RPM in D braked.


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Next test would be at heat soaked , raise RPM to equal 3,000 RPM-alternator and see its maximum output, which I think it may be down to 160-170 amps only if
looking at current data at low RPM. This will need my carbon pile load tester, but its tuning or ramping up the load is not so precise mechanically and extra heat cause load
to change too, due to carbon's own resistance characteristic when hot, hence 15 seconds limit only allowed.

 

Wow....HVAC blower at max speed 5-bar is 20 amps !! 250 watts at 12.1V
I thought max 150 watts it would be.

All values are stabilized, or a reading 5 seconds after speed increase.

ENGINE IS OFF


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I owned the car for 6 years now and only today I realized if I turn ON HVAC via blower button 1 touch up, the minimum speed will be 2 BAR by default.
1 BAR speed is bull-shi-et , almost no air flow.... LOL.

 

Master Surya, I had a wild idea....

what if the car could load-shed your auxiliary lights demand under low voltage condition ?

This is what chassis does normally but a few custom tweaks later and your surging the snut out of all your electronics.

Use a ready-made module from China to manage hysteresis. You wouldn't want load to cycle on/off to create more surge current.

 

Its OK Cali, I will leave it as-is.

I plan to re-check my alternator positive wire and clean the cable lug too. I done that in July 2022 already, when I was doing VVT mini window re-sealing.



I could never clean the oil trace on the winding, that alone can also hamper my alternator cooling capability


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I think in a year or two I must tear down my alternator and give it a good cleaning.


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I must buy that special tool to remove the alternator pulley

 

Your 6x diode rectifier may have gained bad connection from the oil bath.

AC-DC rectified wave form

You can scope the voltage under load for evidence of a missing rectified phase.

The max load at 500.Rpm is from lack of voltage to get enough magnetic field from the rotor coil. When available voltage drops, it colapses rotor field too.

 

The oil trace is not as bad as it seems to other than the windings, its a very slow oil micro leak and not oil spray.
I have cleaned the diode set bolts and nut and carbon brush during the VVT mini window re-sealing in 2022, all good.


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The best cleaning of the windings I could do.


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My diode set is fine, I scoped it already at its retrified output in 2022. I make it a point to test it once a few years.
You wont be able to see raw AC waveform like u posted , unless on a bench with a motor to spin the alternator and we remove the diode set.

The retrified waveform




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Mine.
Blue channel is directly at alternator positive lug.
Red channel is at F32 MR8 ( alternator ) stud.




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rectified AC riples

So yes we can confirm all rectifier diodes are healthy by looking at the riples besides significant spikes from who knows what.

 

Or I can make those noise spikes go away with filter .... ha ha ha
This scopes are so sensitive it is awesome. Anyway I am using AC coupling to make it more sensitive, as suggested by Pico.



See red channel, it is read at F32 , so close to battery and battery is absorbing the noise..








I think the long 3 meter ish fat alternator positive cable to F32 acts like antenna for AC noise in some way too.

 

MS! you want to go spike hunting to kill goofy gremlins??

Dirty electrical spikes are best minimized.
I am sure our chassis is a champ in the noise Dept with all the fancy PWM:

1. engine supersonic fan
2. cabin blower
3. Tank pump 3-Ph. AC
4. ECU Injectors + COP'S
5. LED HL
6. VVT Solenoids

​​​​​​These devices benefit from clean DC power else spikes go right through control to load.

As noted battery low impedance helps clean up spikes.

 

Its allright Cali, the spikes are very low 30 millivolts if seen on a scope and so short a duration like 24 microsecond, again which only a scope can see.
Anyway when anyone scope their car there are bound to be "noise" and spike...within limits.
With injectors and COPs , no way a car electrical system can be as clean as a PC let say.

Alternator itself is a crude not so clean DC power with only diode set, not super stable too actually compared to a decent bench power supply....thus healthy battery its its good friend.

 

Some data of use..............

ENGINE IS ALWAYS OFF. So Voltage would be between 12.6V to 12.3V depending on load.




I did not keep music LOUD for more than 20-30 seconds, but its low amperage use is a surprise. Number 10 and 11.
The rear windscreen defroster is controlled actively by the SAM, it won't kill itself from overheating.
The last test I did on it last week, it failed to power up when I run it too often within a short peiod of time


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The 6 hour to sleep mode , the load profile after closing the door upon test completion.



I have always thought if engine is not runned, the sleep mode will happen fast and not the maximum 6 hours for a car which its last engine kill was more than 6 hours to a few days ago.
It seems Ignition ON albeit engine OFF, if more than 5 minutes, the car decided that the sleep mode is the 6 hours one.

 

I dig my old 2021 archive of 2nd May 2021, before LIN was disconnected and I was video logging the charging algo.
My idle in park was at a high 692 RPM.

This is a hot engine in daytime after running in a decent traffic and not stop and go creeping traffic jam, for 50 minutes and then idling for 15 or so minutes outside my garage,
thus 1 hour 5 minutes total. Coolant was 90C nice, not even close to 95C.
I do not yet have engine bay ambient air temperature sensor back then.



The power consumption is rather high, 50 amps even before low beam turned on. HVAC blower speed would be 4-bar at best and not max 5-bar.
So night time in bad traffic and with low beam ON at extra 8.8amps, I could be looking at minimum 60 amps.
Thus 550 RPM in D braked and at night in bad traffic, if coolant 100C and cooling fan speed will kick more power, seems 65-67 amps is what to be expected for car only power needs, excluding charging the battery.

Damn.......... not a good current load for a heat soaked alternator at 550RPM in D-braked.