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Screen grab of how much our battery is forced to "subsidize" engine electrical current/power requirement while we kick down to do best WOT performance,
when LIN is still connected to alternator and ECM does what it thinks its best for C02 emission ...not for us.
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Remove the ECM intervention and this is how electrical power supply to an engine doing WOT or nice slow cruise should be, no power deficit subsidized by battery.
Stable 14.1V and not dumb-azz 13.0V - 13.1V.
Screen grab of how much our battery is forced to "subsidize" engine electrical current/power requirement while we kick down to do best WOT performance,
when LIN is still connected to alternator and ECM does what it thinks its best for C02 emission ...not for us.
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Remove the ECM intervention and this is how electrical power supply to an engine doing WOT or nice slow cruise should be, no power deficit subsidized by battery.
Stable 14.1V and not dumb-azz 13.0V - 13.1V.
10 minutes of horror charging, above maximum typical charging current of AGM, which is max 30% of Ah rating.
In my case 30% of 80Ah or 24Ah allowed. Best is 20% only for battery longevity.
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The up to 14.8V charging voltage is also something I do not like. Its too high.
When ECM decided that battery is "FULL", it then does the. I-SUCK-YOUR-BATTERY game
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Imagine what happen, when and if : I do not do more idling test from 49th minutes to 65th minutes, and immediately parked my car, and kill engine.
My battery is then no not "fully" charged anymore. To be honest at 14.8V and my battery amperage is still 8amp ish, that mean the battery is not fully charged yet.
If one uses the car 200 days a year, 1 round trip, so twice engine run per day..........400 engine run events per year.
We can't tell which of the 400 engine run will be the unlucky one where ECM does the I-SUCK-YOUR-BATTERY game, but then you turned of the engine seconds later
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18th Sept 2021, is one of the few earliest LIN disconnected tests I done.
After 27th July 2021 , I was already using a new battery and retired the 2018 battery.
Aug 2021 was the time I killed ECO-Start-Stop using Autel, baby Launch Creader Elite for MB does not exist yet.
Back then early 2021 I have always assumed ECO-S-S and Smart Charging is one package algo wise, but it is not.
The 18th Sept 2021 video of LIN-disconnected below is a 33 minutes long, but speed up to become 12 minutes.
From engine COLD start to my destination. Casual slow driving, no traffic jam, good drive.It was a Saturday mid noon.
In layman’s terms, what would you say are the major conclusions that we can take away from the data you saw and presented?
To simply put it :
IF LIN is connected, meaning alternator is being manipulated by ECM for most likely CO2 reduction ..... in most cases we get :
- Shorter battery life , due to battery never get fully charged. Sulphation is what the battery will get. Google this one.
- Too much charging current to a lead acid battery is bad. Keep it below 30% of the battery Ah rating, better 20%. Even lithium ion best reccomended is max 40% of its Ah rating for longevity.
- Battery power OUT or IN, is a chemical reaction, jumpy yoyo charging current is not good as chemical takes time to react.
- The worst offender of all is, our battery is not supposed to power the car when engine is running, it is alternator job.
Only because of electric power steering fast demand for those who spin full lock-2-lock steering fast like me, you will see battery assisting in the power deficit because alternator has delayed response.
In a LIN-connected alternator, ECM will make our battery as power provider ( negative amps on IC display ) for a bit here and there on purpose, while engine is running, which is not a good thing.
- You seen in post #1, how when I do WOT 2 and 3rd gear, the alternator is on purpose reducing its output and battery have to subsidize up to 20+ amps or 240+ watts, and 13V is what we get and not 14V.
What would I risk good firing of COP and injectors by having lower power reserve ? COP is about 20 amps per pulse, injector is about 10 amps per pulse, based on M276.8
If MB smart charging target is battery longevity, I would be pleased. Too bad its target is for C02 reduction, just like start-stop and the 2 stage oil pressure.
In a blue efficiency badged models ( petrol, not diesel ), I seen worse charging profile than mine and less than 2 years battery max life is typical in Jakarta bad traffic jam.
A friend 2010 C200 M271.8 CGI blueffiiency is what I tracked as battery "eater".
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If LIN is still connected, I suggest use 5 amps Ctek charger every week to top up the battery. This should allow the battery to survive longer.
If you want to know your true battery state of health, forget those electronic battery tester.
Get a carbon pile battery tester of minimum 500 amps for CCA test and the electronic load of 25 amps for Reserve Capacity test. This is what I did.
Reserve Capacity @25amps test is a good honest and easy to do test.
One final note : able to crank-start the engine ( warm weasther ) does not mean you battery is healthy, it only meant it has CCA still within 400 amps or 50% of reccomendation..
Cranking is about 220 amps for M276.8 ,inlcuding all computer management of the car and starter spinning at its deisgned speed. Its initial inrush of crank-to-start is 600+ amps for less than 0.5 second.
My original battery from MB has CCA of 800 amps.
One final note :
Do test your alternator cut-in RPM when and if you decided to disconnect the LIN. This is the RPM where alterantor starts to produce voltage above battery voltage and can start charging.
Engine Throttle blip to a bit above 1,000-RPM engine s usually what is needed to kick start the alternator....when in engine WARM start, after that engine can be at 650 RPM idle and alterator will charge.
Above is the behaviour of M271.8 C200 W204 alternator. Maybe pulley ratio is unlike M276.x
For sake of simplicity... once upon a time Surya and myself recognized extreme voltage yo-yo in our stock W212 M276.
There are two distinctstock yoyo styles :
1- the stock swings : 12.6V to 14.9V
2- the buggy "drain by driving" deeper than 12.3V
As it turns out both are bad... ZERO VARIABLE VOLTAGE is what makes the chassis run better.
We now recognize that a very stable voltage is far greater than any type variable voltage.
This is because the ECU ignition unfortunately rely on timely sparks impacted by voltage through COP 25kVAC transformers.
Bosch ECU control W212 Valeo ALT over a LIN Bus.
When left alone ALT-LIN can self-regulate intelligently in a legacy mode.
Without ECU mismanagement of ALT, there is zero yoyo generated to mess up the chassis best behaviors... that is pure bliss.
As it turn out this Bosch feature is used by most car makers (EU/US/JP/KR) and may benefit with same solution.
Last edited by CaliBenzDriver; Feb 24, 2025 at 07:46 AM.
Funny you should ask, i just yesterday did the Gearbox reset (722.9) and almost regret it.
I thought it could get even better but no, I had an almost perfect symbiosis between engine and gearbox and this sort of messed it up.
Nowadays i drive very sedate (like a middle aged man) and it had adapted perfectly to my drivestyle.
Well well, it will adapt to my drivestyle again eventually.
Though I will go thru with the big RESET some day and see if i can notice any differences (hopefully don´t mess up anything for me)
I personally kinda like the start stop function (Shamefully).so i wont disconnect the LIN.
Could this mean that perhaps the Diesel BlueEfficiency such as E250CDI is less affected by these CAN LIN problems?
No idea. I never touched or seen MB W212 diesel. Not sold in my country.
But I would guess the extreme of "poor-charging" in the name of emission.....would be the same too for diesel engine.
After all them MB engineers do all these not for our benefit, it is for less emmision charge per car sold
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Penalties for excess emissionsIf the average CO2 emissions of a manufacturer's fleet exceed its specific emission target in a given year,
the manufacturer must pay – for each of its new vehicles registered in that year – an excess emissions premium of €95 per g/km of target exceedance.
Funny you should ask, i just yesterday did the Gearbox reset (722.9) and almost regret it.
I thought it could get even better but no, I had an almost perfect symbiosis between engine and gearbox and this sort of messed it up.
Nowadays i drive very sedate (like a middle aged man) and it had adapted perfectly to my drivestyle.
Well well, it will adapt to my drivestyle again eventually.
Though I will go thru with the big RESET some day and see if i can notice any differences (hopefully don´t mess up anything for me)
I personally kinda like the start stop function (Shamefully).so i wont disconnect the LIN.
You know the slow-poke low Rpm gear slugging is not caused by tranny but the engine itself.
It's not tranny that shifts 5th gear at 20mph... it's the engine module!
Poor tranny performance is usually caused by the engine except all slippery clutch: that's 100% tranny.
> How things go...:
Engine triggers the shift points
Tranny executes the gear shifts
CAN delays data between the two
Voltage swings impact networking.
Last edited by CaliBenzDriver; Mar 21, 2025 at 02:31 PM.
oh, this beaviour is normal then. Yesterday my battery voltage is dropped to 11.9V (for 8 months battery!) , therefore I disconnect battery from the car and do a recond mode using CTEK battery charger.
When I reconnect the battery the car this morning and driving it, I notice IB always in negative numbers, even with main beam is on :O (with UB of 12.6v) . The IB goes positive when the door is open and voltage jumped to 14v, but after a minute from door closing UB back to 12.6 and IB back to negative numbers.
another thing which triggers battery charging is when doing WOT, on WOT UB jumped to 14V and IB +40A :O
I think the car purposely disharging my 100% battery (since it was charged on external charger) to until 80% except in certain conditions (such as opening the door and WOT)
Should I disconnect the LIN cable? where is this cable will it cause overcharging the battery?
oh, this beaviour is normal then. Yesterday my battery voltage is dropped to 11.9V (for 8 months battery!) , therefore I disconnect battery from the car and do a recond mode using CTEK battery charger.
When I reconnect the battery the car this morning and driving it, I notice IB always in negative numbers, even with main beam is on :O (with UB of 12.6v) . The IB goes positive when the door is open and voltage jumped to 14v, but after a minute from door closing UB back to 12.6 and IB back to negative numbers.
another thing which triggers battery charging is when doing WOT, on WOT UB jumped to 14V and IB +40A :O
I think the car purposely disharging my 100% battery (since it was charged on external charger) to until 80% except in certain conditions (such as opening the door and WOT)
Should I disconnect the LIN cable? where is this cable will it cause overcharging the battery?
12.6V float is not an abnormal voltage. It is still above battery discharge.
Anything significantly below 12.5V such as 12.3V or less will be a effective "drain by driving".
40A high charge current shows a discharged battery condition.
WOT or HL or driver door all request voltage to rise to near 13.7V... totally expected.
I understand your battery is not an AGM type... do NOT consider "ALT-LIN": it will overcharge your liquid electrolyte battery.
Last edited by CaliBenzDriver; Apr 22, 2026 at 01:40 AM.
12.6V float is not an abnormal discharging voltage. It is still above discharge.
Anything significantly below 12.5V such as 12.3V or less will be a effective "drain by driving".
40A high charge current shows a discharged battery condition.
WOT, HL and driver door all request voltage to rise to near 13.7V... totally expected.
I gathered your battery in use is not an AGM type... don't consider using ALT-LIN it will overcharge your regular battery.
ok i will not cut the ALT-LIN then
While 12.6 is not discharging voltage, but the IB numbers shows mostly on negative numbers. -Its about 2 to -10A for one hour of driving in jakarta. The only thing triggers positive IB numbers is WOT and opening the door. I guess this is normal since the car thinks oh this battery is at 100%? lets drain it to 80% to save fuel But why 1 hour of driving is still making negative numbers IB (which means discharging the battery right?)
I drove early in the monring, the main beam were on 80% of the time.
While 12.6 is not discharging voltage, but the IB numbers shows mostly on negative numbers. -Its about 2 to -10A for one hour of driving in jakarta. The only thing triggers positive IB numbers is WOT and opening the door. I guess this is normal since the car thinks oh this battery is at 100%? lets drain it to 80% to save fuel But why 1 hour of driving is still making negative numbers IB (which means discharging the battery right?)
I drove early in the monring, the main beam were on 80% of the time.
there is no true battery discharging at 12.6V or above.
The "surface charge" above 12.6V comes on and off easily. Its not accounted as part of charge.
The bursts of 14.9V opportunistic charge call for use of an AGM battery.
This is counter intuitive that negative IB is a discharge yes, but is not battery drain above 12.6V.
Battery cells condition are based on voltage.
Last edited by CaliBenzDriver; Apr 22, 2026 at 01:52 AM.
Try to remove your LIN connector at the alternator and then tell us the voltage and amperage reading.
If the overall design of your alternator is the same as my Valeo alternator voltage regulator , 14.2V is the highest you will see when LIN disconnected.
Safer than with LIN connected if you are seeing 14.5V or higher.
thanks pak @S-Prihadi , I will look into that but in the meantime I will check daily voltage after daily driving it for a few days. It does jump to 14.7V briefly after cold start. During the drive stays mostly on 12.6v, on door opening 13.6v. When engine shutoff after a drive it stays at 12.5-12.6 so far. I will check again in the next morning hopefully it did not drop much
The alternator can not do proper full charge of battery like a charger. It is given.
Even with ALT-LIN disconnected, charging the battery once a week is best for long life.
Charge it when after washing the car, where door opening is long time and often.
You have OBD2 gauge too right ? See how much power it uses during car deep sleep. OBD2 port is Circuit 30, always hot ( has power ).
I think if you disconnect your ALT-LIN, it will benefit your regular wet cell battery ( non-AGM ) too, from the polite charging amps and not as high as 14.7V.
Mercedes Teases Updated EQS With Steer-By-Wire and a Yoke
Slideshow: The 2027 update adds a fully digital steering system, revised styling, and potential charging upgrades as the company looks to revive interest in the luxury EV.
Slideshow: From problematic air suspensions to early dual-clutch transmission issues, these specific models and years stand out as the least dependable modern Mercedes vehicles.
...not for us.
