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So I was driving around today and had my Autel around and was checking live data when I noticed that my alternator charges idling or in motion between 12.5 - 12.75V.
I find that to be quite low, come to think of it, sometimes on a cold start after sitting for 3-4 days I noticed the interior lights flicker once or twice, but nothing major.
Could this be a sign for a bad voltage regulator or the alternator itself?
I'll be changing pulleys and belt, so I was wondering if I can throw in a new voltage regulator while I'm in there if that's culprit?
If your battery is healthy, and fully charged the "smart alternator" will lower the charging voltage until no current us required.
Put a load on it and verify the voltage and current. Which load? Lights ON, AC ON MAXCool and check again current and voltage
Battery is couple of months old. I can see in the history that the battery has been changed twice, I'm sorry I should mention I have a 2011 E350 RWD.
I find it quite odd, that in park on neutral I have proper voltage of 13.6 - 13.8, but in drive is between 12.5 and 12.75, but I've never dealt with a smart alternator.
The picture above is with the at a stop light + ac on, but not max cool.
13.6-13.8 is with the ac on + lights on idling.
Battery is couple of months old. I can see in the history that the battery has been changed twice, I'm sorry I should mention I have a 2011 E350 RWD.
I find it quite odd, that in park on neutral I have proper voltage of 13.6 - 13.8, but in drive is between 12.5 and 12.75, but I've never dealt with a smart alternator.
The picture above is with the at a stop light + ac on, but not max cool.
13.6-13.8 is with the ac on + lights on idling.
I have a 2010 E550 and 2012 S550 and both of them are so called "Blue Efficiency" cars. Part of this is the smart battery charging system.
Driving the car gives voltage at around the 12.5 - 12.8 V but look at it when you slow down the car. Voltage shoots up to around 14.5V as the car is slowing down and heavier alternator load can be used without sacrificing fuel consumption, i.e. using heavier load on alternator will actually help slowing the car down.
You should see the higher voltage when slowing down, if not, then your smart charging system may not be working correctly.
The whacky voltage reading you are seeing is how MB WANTED it to be, in the name of ECO bull-shiet.
Engine computer tries to keep your battery at approx 80% state of charge only.
If you log your battery voltage at 1 data point per second using OBD2 gauge, you will be surprised at how often the ECM on purpose will discharge your battery to make
room for the 80% only state of charge.
If you video log your alternator output using your scanner at the BATTERY SENSOR module, you will be suprised at how violent the charging amps can be at certain times
and also its discharging.
I am done with this stupid YoYo charging MB on purpose designed a W212 to be, I have un-plugged my LIN wire to the alternator, thus ECM can no longer tell alternator what to do, and the alternator will use its simple and polite charging profile from its awesome built in charge controller.
You will get soft DTC when you scan the car ECM when you removed the LIN wire to alternator, but there is no check engine light whatsoever.
If you car has Blue Efficiency badge, its even worse the level of stupidity on how much the discharged level allowed on the battery,
case to note C200 W204 CGI of year 2010. It has the dumb-azz blue efficiency badge. It is gasoline engine.
Don't confuse AdBlue diesel treatment with Blue-Efficiency of gasoline engine.
E250 W212 uses the same engine as C204 C200 CGI
.
Last edited by S-Prihadi; 09-11-2024 at 04:19 AM.
Reason: add info
The whacky voltage reading you are seeing is how MB WANTED it to be, in the name of ECO bull-shiet.
Engine computer tries to keep your battery at approx 80% state of charge only.
If you log your battery voltage at 1 data point per second using OBD2 gauge, you will be surprised at how often the ECM on purpose will discharge your battery to make
room for the 80% only state of charge.
If you video log your alternator output using your scanner at the BATTERY SENSOR module, you will be suprised at how violent the charging amps can be at certain times
and also its discharging.
I am done with this stupid YoYo charging MB on purpose designed a W212 to be, I have un-plugged my LIN wire to the alternator, thus ECM can no longer tell alternator what to do, and the alternator will use its simple and polite charging profile from its awesome built in charge controller.
You will get soft DTC when you scan the car ECM when you removed the LIN wire to alternator, but there is no check engine light whatsoever.
If you car has Blue Efficiency badge, its even worse the level of stupidity on how much the discharged level allowed on the battery,
case to note C200 W204 CGI of year 2010. It has the dumb-azz blue efficiency badge. It is gasoline engine.
Don't confuse AdBlue diesel treatment with Blue-Efficiency of gasoline engine.
Using one of these in the cig socket you can monitor the battery voltage
When your foot is on the gas pedal the battery charges at about 12.6 volts
Take your foot off the gas and you will see the voltage shoot up to 14.8 volts
Clever design. The engine doesn't have to fight against an electrical load when it doesn't need to
PFL205.064 with M276.823 (Oil pump solenoid defeated)
Originally Posted by Bruce Hubbard
Using one of these in the cig socket you can monitor the battery voltage
When your foot is on the gas pedal the battery charges at about 12.6 volts
Take your foot off the gas and you will see the voltage shoot up to 14.8 volts
Clever design. The engine doesn't have to fight against an electrical load when it doesn't need to
That is a neat gadget. I am not sure if the W212 has this information but the W205 has battery status built-in in the workshop menu. https://mbworld.org/forums/c-class-w...ry-health.html
As well as the vehicle data menu in the infotainment.
That is a neat gadget. I am not sure if the W212 has this information but the W205 has battery status built-in in the workshop menu. https://mbworld.org/forums/c-class-w...ry-health.html
As well as the vehicle data menu in the infotainment.
Correct. Here the procedure for the W212 generational cousin, W166
What is a normal amperage and voltage when fully charged?
: )
I have now battled this chaos for over a decade... let me help ya see daylight *.
✌️
******** > The Long Story Short :
My hands on testing tells me factory solderless modules silently screw up CGW without any warning thereby impacting: engine GDI + tranny shifts + batteries yoyo with the results we come to enjoy as MB ownership.
*******
-- Answer to a good question....
what's normal current/voltage of charged Batt ?
Normally from only a couple Amps down to zero at 12.6V float.
-- You need to realize the IC displays the battery current alone, not the total ALT current. Let that sink in a bit... displays is limited to batt vitals, not chassis.
-- When the nearly full battery charge is switched to 12.6V float maintenance voltage (just like a CTEK!), the dismal current is near 1, 2, 3Amps. very small ie. battery is not accepting more charge.
-- Right after starting up, battery needs to recover its effort: 15Amp current rapidly decreasing down to 5Amps.
If you see current above 20Amp that is not too good unless you play the radio with engine-Off sort of things...
-- The Battery Amperage displayed is the measure of current related to battery charge level and charge voltage.
> The A-Team:
There are 2x bosses deciding on what voltage to request from the ALT regulator LIN module.
The ECU take precedence over the R-SAM request and are mutually exclusive.
> They both work at a different phase in the charge cycle !
-1- The ECU handles battery charge cycle (13.7v; 14.4v; 14.9v).
-2- The R-SAM controls powering the chassis load demands with 12.6v after batt is recognized being well charged up.
The disfunctional part is when R-SAM REQUESTS ARE LOST by the overwhelmed CGW Module on the way to reaching the ECU.... at that point the VOLTAGE CONTROL GOES OPEN-LOOP through the floor below 11.xV
For some unclear reason world-class transportation learder Robert Bosch decided to implement a rooky non-failsafe control in then best GDI ECU computer... go figure, amazin'
When ECU fails to receive SAM request batt gets drained empty with shots of 90A during decelerations... that's punches of over 1300W heat dissipated for extended period (not just quick starter crank duty).
Battery enclosed in plastic has no way to dissipate 1300W ... another new $200 battery.
> OVERALL NUMBERS:
-- 10A Low current...
is perfectly healthy
-- 25A Medium current...
depicts a low batt charge
-- 40A High current...
trouble around the corner
> INTERESTING:
When ALT voltage switches between opportunistic 14.9V deceleration back to 12.6V float... a negative/discharge current is shown.
Not a problem!
That is the "surface charge" being used up by the chassis like a capacitor supplying power.
Lead-acid AGM battery only discharge below 12.5V.
The Hyundai module integrates a temperature sensor to limit currents when battery got hot acting like a capacitor.
At that point the 14.9V opportunistic shots are stopped.
Voltage remains on 12.6V float only.
> EXTRA FANCY:
To decrease engine load during acceleration when R-SAM is managing 12.6V chassis power, the voltage is switched down to 12.5V for minimal load. [that's when hell has additional chance to break loose at 12.5 than 12.6 !!]
> BASIC PWR:
Powering the chassis basic load is about 25 to 30A for coils, injectors, in-tank pump without lights, A/C, fan. This basic load is always powered by ALT.
Main Battery hardly does any powering outside starter crank and "surface charge/discharge" tricks.
Your best friend for proper voltage Mgt is a good main GND strap and a working CGW gateway.
Many transportation use that Bosch design with all its yoyo downfalls. Ford's a popular one!
> WARNING SECTION...
-- if you witness 12.3v or less... meaning battery voltage keeps draining down into 11.xV territory driving on the highway when you expect to be getting nice "12.6V float"
-- that's when you know your chassis has dangerous limp-mode X-Mas display dead engine at 65mph.
-- This is regardless of happy-happy voltage after starting! That part is no problem. R-SAM float is what's busted here.
-- ALT can work well when instructed correctly
Its just the wonky CAN trying to get you.
-- As far as I can tell... this YoYo is enabled in every W212 chassis built to feature pressed-pin CAN issues.
-- Be safe, empower yourself not to become NHTSA statistics... drive with voltage/amp displayed.
It's free.
🤞
*: courtesy of #1:MS! joint voltage yoyo research.
Last edited by CaliBenzDriver; 09-27-2024 at 01:59 AM.
Reason: recognized @s-prihady
PFL205.064 with M276.823 (Oil pump solenoid defeated)
Originally Posted by CaliBenzDriver
I have now battled this chaos for over a decade... let me help ya see daylight *.
✌️
******** > The Long Story Short :
My hands on testing tells me factory solderless modules silently screw up CGW without any warning thereby impacting: engine GDI + tranny shifts + batteries yoyo with the results we come to enjoy as MB ownership.
*******
-- Answer to a good question....
what's normal current/voltage of charged Batt ?
Normally from only a couple Amps down to zero at 12.6V float.
-- You need to realize the IC displays the battery current alone, not the total ALT current. Let that sink in a bit... displays is limited to batt vitals, not chassis.
-- When the nearly full battery charge is switched to 12.6V float maintenance voltage (just like a CTEK!), the dismal current is near 1, 2, 3Amps. very small ie. battery is not accepting more charge.
-- Right after starting up, battery needs to recover its effort: 15Amp current rapidly decreasing down to 5Amps.
If you see current above 20Amp that is not too good unless you play the radio with engine-Off sort of things...
-- The Battery Amperage displayed is the measure of current related to battery charge level and charge voltage.
> The A-Team:
There are 2x bosses deciding on what voltage to request from the ALT regulator LIN module.
The ECU take precedence over the R-SAM request and are mutually exclusive.
> They both work at a different phase in the charge cycle !
-1- The ECU handles battery charge cycle (13.7v; 14.4v; 14.9v).
-2- The R-SAM controls powering the chassis load demands with 12.6v after batt is recognized being well charged up.
The disfunctional part is when R-SAM REQUESTS ARE LOST by the overwhelmed CGW Module on the way to reaching the ECU.... at that point the VOLTAGE CONTROL GOES OPEN-LOOP through the floor below 11.xV
For some unclear reason world-class transportation learder Robert Bosch decided to implement a rooky non-failsafe control in then best GDI ECU computer... go figure, amazin'
When ECU fails to receive SAM request batt gets drained empty with shots of 90A during decelerations... that's punches of over 1300W heat dissipated for extended period (not just quick starter crank duty).
Battery enclosed in plastic has no way to dissipate 1300W ... another new $200 battery.
> OVERALL NUMBERS:
-- 10A Low current...
is perfectly healthy
-- 25A Medium current...
depicts a low batt charge
-- 40A High current...
trouble around the corner
> INTERESTING:
When ALT voltage switches between opportunistic 14.9V deceleration back to 12.6V float... a negative/discharge current is shown.
Not a problem!
That is the "surface charge" being used up by the chassis like a capacitor supplying power.
Lead-acid AGM battery only discharge below 12.5V.
The Hyundai module integrates a temperature sensor to limit currents when battery got hot acting like a capacitor.
At that point the 14.9V opportunistic shots are stopped.
Voltage remains on 12.6V float only.
> EXTRA FANCY:
To decrease engine load during acceleration when R-SAM is managing 12.6V chassis power, the voltage is switched down to 12.5V for minimal load. [that's when hell has additional chance to break loose at 12.5 than 12.6 !!]
> BASIC PWR:
Powering the chassis basic load is about 25 to 30A for coils, injectors, in-tank pump without lights, A/C, fan. This basic load is always powered by ALT.
Main Battery hardly does any powering outside starter crank and "surface charge/discharge" tricks.
Your best friend for proper voltage Mgt is a good main GND strap and a working CGW gateway.
Many transportation use that Bosch design with all its yoyo downfalls. Ford's a popular one!
> WARNING SECTION...
-- if you witness 12.3v or less... meaning battery voltage keeps draining down into 11.xV territory driving on the highway when you expect to be getting nice "12.6V float"
-- that's when you know your chassis has dangerous limp-mode X-Mas display dead engine at 65mph.
-- This is regardless of happy-happy voltage after starting! That part is no problem. R-SAM float is what's busted here.
-- ALT can work well when instructed correctly
Its just the wonky CAN trying to get you.
-- As far as I can tell... this YoYo is enabled in every W212 chassis built to feature pressed-pin CAN issues.
-- Be safe, empower yourself not to become NHTSA statistics... drive with voltage/amp displayed.
It's free.
🤞
*: courtesy of #1:MS! joint voltage yoyo research.
Very very detailed and helpful, much appreciated : )
Amazing random progress was made today... I finally reproduced the "11.xV BATTERY DRAIN" while idling.
This Sunday started well. We drove out to meet friends for outdoor activities.
Within less than 5mn driving:
ECO GREEN flag was ready
Amperage was already low under 10A
engine still cold: Amp low.. batt well charged up 👍
That says battery was still well charged from yesterday driving.
It has not seen a battery charger since I returned from traveling 10 days and about 500Miles ago.
The 12.6v / 14.9v dynamic voltage was working as designed - Very rewarding results
Then wife decided to go shopping and I hooked my scanner. I uploaded the latest LAUNCH firmware update over 5G-tethering, scanned the whole chassis emailed myself a report then decided to poke around the ECO settings.
I went into ECU, R-SAM, CGW... found some ECO parameters to enable/disable... did not change anything but CGW still went ahead and "Applied... please reboot now... blabla" all along engine idling.
Then I see my battery voltage display go into 12.3v -30A - Holly cow, no thank you! I turned on my headlights: sanity's restored for now!
So that tells me... When ECU misses battery data streaming from R-SAM, ALT CTL with float voltage goes out of control into an "open loop".
All this caused by a single CGW data stream glitch or interruption.
Not the Batt module
Not the R-SAM
Not the ECU itself
You have the description above to reproduce that Bosch bug.
This float voltage regulation is what's proven not fault-toletant.
ECU quits controlling ALT "12.6v float voltage" while engine is running. No default voltage value gets substituted. Battery gets drained into dismal 11.xV to supply 100% of chassis load until "X-Mas tree" network crash is displayed while driving.
Exceptions are HL:ON + deceleration 90Amp shots into soon empty battery.
Drive carefully.
I am very curious to know more so I have not rebooted the chassis yet to clear the mess up conditions.
We have a BD dinner party to drive too and back... let's see how this morning event affect the "battery charge status" ECO/Amps ??
More "open-loop" instead of "12.6v float" or back to best behavior??
The bad guy is still "CGW for solderless chassis" and the bug is in "ECU missing default".
Last edited by CaliBenzDriver; Yesterday at 07:23 PM.
good news!
No chassis reboot necessary this time. Only a key cycle with sleep cleared the loss of control caused by CGW.
The ECU rejoined the R-SAM across the CGW gateway as if nothing ever happened.
The ECU awareness of battery is consistent with charge that lost.
In conclusion we can say only a key-cycle (plus sleep) is necessary for ECU to re-establish a fresh connection good for sometimes when unstable network drops packets.
09-10-2024, 06:50 PM
