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This is a much more complicated question than you think. In a typical german fashion the charging systems on newer mercedes aren't so simplistic. Germans don't think of a battery as only a source of power. They think of it as a shock absorber for the electronic system. When we do battery tests to determine whether they are good or not, it isn't testing it for load or max amperage output. Instead the tester is introducing a/c voltage across the battery and seeing how much comes out the other side to determine its health. I'd start by swapping to a normal battery to see if you actually have a problem. More than likely it is your newly found Lithium ion battery. There are a couple things to keep in mind. Good voltage doesn't equal good amperage . Amperage is what recharges the battery. Typical normal operating voltage is in the 13.2-13.4 voltage zone but that isn't set in stone. You should be able to view battery voltage and amperage draw/gain (sometimes displayed with an i ) in the dealership service menu area (where you go to reset the service indicator/dynomode etc...). The charging algorithms on these vehicles don't just blast the alternator constantly charging the crap out of the battery. This is can work and did work for decades but ultimately your battery would last 3-4yrs tops. It's actually bad for it. It's actually not good for the battery to be at 100%, ideally they are in the best state at 80-90% . This is attained by cycling the alternator on and off. On our cars the M.E. (ecu) provides the lin bus signal for demand output of the alternator, but that is determined by the battery sensor which sends it's data to either the front or rear sam determining the state of charge. From there via can the ecu is told what it needs to do to achieve the results it wants. They also use this for an advantage in fuel efficiency. They will typically decrease alternator output on acceleration and increase it on decel or engine braking since its basically free energy. Think of it similar to a hybrid using braking regen to charge the battery.
The mercedes lithium ion batteries all have a built in control module and specific coding to utilize it. I haven't had an opportunity to disect or compare the differences or coding changes in the other modules side by side. Obviously the newer models that came with optional li batteries will have the necessary coding changes which could be retrofitted back and forth, but I don't know that ours even have the option or coding data available.
Basically my thoughts are it's highly likely there is nothing wrong with your car it just doesn't like your battery..
This is valid for cars that have the Option 909, Alternator Management.
My car has it.
As an example, some 507 don't have the option 909, so not all C63 have it.
This is also why the answers in this thread differ, some having had a good time with small batteries.
Having a battery sensor is a sign that you have the option 909 and then you're best off running the factory battery, with the full Ah that the car needs.
And yes, it will affect the torque output, as when you run it WOT, not having the full Ah, the car running basically on battery at that time, the ECU has to take action.
I have been looking into the OEM lithium SLS battery as well, but had no clear information so far.
And the Lithium battery needs a special charge regulator, which I am guessing is built into it, as a way to make the battery plug and play.
And I do recall that Xentry allows monitoring the battey voltage at the battery sensor, maybe even logging it.
2012 P31 C63 Coupe Trackrat, 2019 GLE63S Coupe Beast
BTW I pulled my full data card. I DO have ‘909 Alternator Management’. This must be why I was seeing voltage fluctuate 11.5-12.5 during cruising - sounds like that may be normal for cars with this option. So how to disable that and get the car to give me 14V all the time?
Originally Posted by roadtalontsi
On another note blkrkt. I bet if you unplug the sensor on the battery ground it'll throw a fault and default to max output on the alternator
If I take the battery sensor off of the battery ground, will that essentially do it @Vladds@roadtalontsi ?
Finally got around to changing out the voltage regulator. Plenty of room to do it on the car but you have to squeeze your arm in the tight space between the swaybar and lower control arm. Remove plastic under car. Disconnect wires, unscrew 3 little screws for the cover, 4 screws for the regulator, pull off. Here is the old (left) vs new (right). The new contacts measure 17mm and the old are at 12mm. 35k miles on the car. I’d say that this should be a maintenance item for those of you closing in on 100k miles.
If this was my car, I would look into turning the option off the right way, via Xentry.
I will look and see if there's an option in the area that deals with the sensor. Even greyed out.
Other than this, I would not have a way to know what the rear SAM is designed to do once the sensor goes missing, other than store a code.
Of course it stands to logic that it would allow the complete voltage through the system, probably by interacting with the alternator's voltage regulator.
But with this kind of stuff and knowing the love affair between German engineering and Byzantine complication, there surely is some "secondary routine" where in certain situations the SAM would still clip the voltage, to protect who knows what. And usually that information is not available to the public.
A mechanic is not credited to be an engineer. A mechanic follows written steps and is allowed to have some intuition as far as Factory engineers are concerned. So the amount of information that the factory discloses to mechanics via WIS and other channels, which in turn makes its way to us, is also limited.
The concept of design (what happens if you yank the sensor) we won't know.
Oh, BTW, my sensor and the SAM were throwing a code. So I replaced it and the replacement sensor did not come sealed 100%.
I thought this is just me being paranoid.
Then with the new sensor the code came back and then left.
Due to the nature of operation of this equipment even the code is elusive.
2012 P31 C63 Coupe Trackrat, 2019 GLE63S Coupe Beast
Originally Posted by Vladds
If this was my car, I would look into turning the option off the right way, via Xentry.
I will look and see if there's an option in the area that deals with the sensor. Even greyed out.
Other than this, I would not have a way to know what the rear SAM is designed to do once the sensor goes missing, other than store a code.
Of course it stands to logic that it would allow the complete voltage through the system, probably by interacting with the alternator's voltage regulator.
But with this kind of stuff and knowing the love affair between German engineering and Byzantine complication, there surely is some "secondary routine" where in certain situations the SAM would still clip the voltage, to protect who knows what. And usually that information is not available to the public.
A mechanic is not credited to be an engineer. A mechanic follows written steps and is allowed to have some intuition as far as Factory engineers are concerned. So the amount of information that the factory discloses to mechanics via WIS and other channels, which in turn makes its way to us, is also limited.
The concept of design (what happens if you yank the sensor) we won't know.
Oh, BTW, my sensor and the SAM were throwing a code. So I replaced it and the replacement sensor did not come sealed 100%.
I thought this is just me being paranoid.
Then with the new sensor the code came back and then left.
Due to the nature of operation of this equipment even the code is elusive.
Totally agree on doing it the “right way”, thanks for taking a look at Xentry. I’m about to pick one up from mbstartool.com and am looking forward to fixing a lot of things like this and the airbags and seatbelts and missing latches and smog pump and.....
BTW I pulled my full data card. I DO have ‘909 Alternator Management’. This must be why I was seeing voltage fluctuate 11.5-12.5 during cruising - sounds like that may be normal for cars with this option. So how to disable that and get the car to give me 14V all the time?
If I take the battery sensor off of the battery ground, will that essentially do it @Vladds@roadtalontsi ?
Finally got around to changing out the voltage regulator. Plenty of room to do it on the car but you have to squeeze your arm in the tight space between the swaybar and lower control arm. Remove plastic under car. Disconnect wires, unscrew 3 little screws for the cover, 4 screws for the regulator, pull off. Here is the old (left) vs new (right). The new contacts measure 17mm and the old are at 12mm. 35k miles on the car. I’d say that this should be a maintenance item for those of you closing in on 100k miles.
Thanks mate! I didn't think to replace my voltage regulator until I saw this post. I agree. This should be a maintenance item to replace at 100k miles. I'm 5k shy from that.Thumbs up
Not sure on this either. Uncharted territory like Vladds mentioned. I'll look at some coding stuff when i get a chance. I can also see what happens if i unplug my sensor too, other than getting the fault. Who cares if you have a fault on the cluster if it makes it work. The problem with not being one of the engineers that developed this stuff is a lot of it isn't really descriptive. Sure you have easy common sense things that list build codes / equipment options with a yes or no. Some codings say random stuff like if it said charge management series.... and you had options 1-5. with no idea what any of them do. Or just something that will say Architecture 3. yes or no. That's where trying to mess with this stuff can be quite difficult. If it flat out says charge management yes or no, that wont be difficult lol.
2012 P31 C63 Coupe Trackrat, 2019 GLE63S Coupe Beast
Originally Posted by roadtalontsi
Not sure on this either. Uncharted territory like Vladds mentioned. I'll look at some coding stuff when i get a chance. I can also see what happens if i unplug my sensor too, other than getting the fault. Who cares if you have a fault on the cluster if it makes it work. The problem with not being one of the engineers that developed this stuff is a lot of it isn't really descriptive. Sure you have easy common sense things that list build codes / equipment options with a yes or no. Some codings say random stuff like if it said charge management series.... and you had options 1-5. with no idea what any of them do. Or just something that will say Architecture 3. yes or no. That's where trying to mess with this stuff can be quite difficult. If it flat out says charge management yes or no, that wont be difficult lol.
Thanks for this, have been reading a lot about BMS/IBS systems. Seems to be pretty evenly split on what happens when you remove the battery sensor. About half default the alternator to maximum output, which is what I’m looking for. The others seem to default to a safe/limp mode where alternator output is 13.5v. Still reading but I think there’s only one way to find out for sure...
2012 P31 C63 Coupe Trackrat, 2019 GLE63S Coupe Beast
So. Got a new VoltPhreaks battery with much higher capacity in aH. Kept it on the trickle charger for weeks. Went for a nice drive in the canyons the other day. Car was great. Came home and parked. Battery died immediately.
With a new voltage regulator in there, it’s got to be the battery sensor and alternator management that’s ruining my life. Unplugged the sensor and will drive again this weekend to see what happens.
Any luck looking through the coding guys? I really need to find a way to bypass this stupid shít.
So. Got a new VoltPhreaks battery with much higher capacity in aH. Kept it on the trickle charger for weeks. Went for a nice drive in the canyons the other day. Car was great. Came home and parked. Battery died immediately.
With a new voltage regulator in there, it’s got to be the battery sensor and alternator management that’s ruining my life. Unplugged the sensor and will drive again this weekend to see what happens.
Any luck looking through the coding guys? I really need to find a way to bypass this stupid shít.
I had this problem with my car also. It would drain battery over night. Drove me nuts and I got 2 brand new batteries. The other day I locked the car and the radio stayed on lol.
2012 P31 C63 Coupe Trackrat, 2019 GLE63S Coupe Beast
Originally Posted by skratch77
I had this problem with my car also. It would drain battery over night. Drove me nuts and I got 2 brand new batteries. The other day I locked the car and the radio stayed on lol.
Mine went away on its own.
Are you using a lithium battery too? And do you have option 909 Alternator Management on your car?
2012 P31 C63 Coupe Trackrat, 2019 GLE63S Coupe Beast
So, I was going to write a big long post with some of the info I found researching IBS and battery sensors (lot of high-power audio guys have been through this). In short the steps I was going to take are:
1) try unplugging the battery sensor first to see if that fixed my charging issue
2) figure out the right resistor to use on the voltage regulator to fool the car into thinking it was always way undercharged (Mike Singer at Singer Alternators created a pigtail that works on Toyotas)
3) try to find coding to turn the system off
4) buy a new sensor and hope that was the issue
5) push the car off a cliff and start over
Well, I’m happy to report that unplugging the battery sensor seems to have done the trick. Thanks @roadtalontsi I read a ton about this, and after seeing lots of BMW, Ford, Toyota, Subaru and Honda stories, eventually found a guy on a UK MB forum who said he did this on his SLK55 for a similar issue. That was enough for me.
Went out this morning to a totally dead battery, wouldn’t even crank. Jumped it and got in for a drive through the canyons. Over the course of 2 hours - stop and go, highway, stopped for gas, canyons, WOT and cruising - voltage stayed pegged at 13.9-14V with very occasional drops to 12.9-13.1. No problems whatsoever with any other systems, and in fact my idle was more stable than before.
It’s only one day, and I still may try to make a more permanent fix to get closer to 15V, but this is far better than the prior behavior of 11V charging and other problems with the battery sensor connected.
So if you have option ‘909 Alternator Management’ and want to run a lithium battery or just feel that your AGM battery isn’t charging sufficiently (due to accessories or audio or whatever), this seems to be the easy solution.
For diagnostic purposes, if the hood is up the system will command max charging from the alternator. So if you have ****ty voltages, pop the hood and re-test. If it is the battery management system pulling it down, it will stop and you will see it.
I'm not sure on your specific car but most of the later MB products have a 'Battery Replacement' program that needs to be run when the battery is changed. Due to decreasing capacity of a traditional battery, they start to charge it less and less as time goes on. So you just put a battery in and don't tell the car, it continues to undercharge your new battery. If you perform the reset using Xentry/SDS, it will go back to charging it full blast as it used to (well to about 80% full). I posted the GF doc for the battery management system somewhere on here but I don't know how long ago it was.
2012 P31 C63 Coupe Trackrat, 2019 GLE63S Coupe Beast
Car has sat for a week, battery still at 12.9V and no crazy errors.
Response today from Mike Singer:
”i do a lot of lexus toyota etc but have zero experience with the benz as far as this goes
i can tell you this though. the lithium batteries throw out current so quickly it is why the sense acts funny and usually triggers an error light even on some cars
the solution for us was to externally regulate the alternator
In your case most fancy cars like BMW benz etc have a failsafe system that makes the alt still charge without the plug plugged into the alt if there is one for the L wire
maybe try running it unplugged if the alt still charges if you don't end externally regulating the alt “
I think that you succeeded at what you set out to do. And now we have some additional information about how this system works.
But regarding the gains...
You now are able to use the LiPo battery and therefore save I don't know, 20 lbs?
But the tension from the alternator on the belt is removing from the power at the crank 2-5 HP? Translated to the wheels 3-6 HP?
And the problem is that once you're at maximum power that's a negligible amount.
But what about when the car is idling and you prepare to floor it?
What is the power output of the M156 in idle?
Is it 20 HP?
Then the 5 HP is no joke.
Of course, the concept of power output in idle is tricky because power is produced against a load.
But in the end there is an output in idle. There are internal frictions etc.
I think that the definition is the amount of power needed to turn the crank at idle RPM by defeating all the possible friction and belt drag.
Let me post here one engineering item. The power loss in defeating friction is maximum when setting an object in motion.
This is why there is a gearbox. In first gear, the torque at the wheels is close to 1000 fl lbs.
this is because the gearbox is a torque multiplication device and because you need a lot of torque to get 3000 lb of a car rolling.
With this knowledge, did you know that the new mild hybrid systems for some cars use the starter motor to accelerate the vehicle from stopped? The starter only assists for one complete wheel rotation.
How much HP does it provide extra, 15?
But the effect is very noticeable. Because the output off of idle is not that much and the demand for power is high.
Even set to full voltage the alternator is not drawing full engine power as it isn't putting out full amperage unless needed. Power lost at idle is inconsequential, you just open the throttle a tad more. He is actively racing the car and the added weight savings is a big deal, more than most would care.
The hybrid systems are not using the conventional starter for anything but turning the engine back on. The hybrid drive unit, be it belt driven like an alternator on some 48v systems or in place of the torque converter in "full hybrid" systems does do more work at low rpms because electric motors are inherently stronger at low rpm and therefore more suited to moving the vehicle off from a stop, yes.
I found in dyno sheets that the M156 May be putting out around 75-85 crank HP as it's WOT, off the idle.
More than I thought.
You're right that the alternator mechanical resistance is dependent on the Amperage demand that it's covering.
For track racing won't make a difference.
Drag racing I think it will and gas mileage especially when you run the car through the car wash weekly, it will.
Hybrid, I was talking about the mild hybrid 48 volt system, especially as shown in the Ram
Trucks.
I've nothing to add other than wanting to say that I loved this post. Learning about the intricacies of the systems on this car is considerably more fun than reading about carbon fiber wrapped toilet paper holders and rim offsets.
So I have a Voltphreaks VPH750 lithium battery. I like it. It has discharge protection that shuts off the battery whenever it runs down to a level needed to start the car. So while I come back to a dead car every couple of drives, all I have to do is turn the battery back on and the car will start right up. So far so good. Here are the specs:
I’ve had my car back on the road for a couple of weeks now, and took my first long drive yesterday, ~200mi up to Paso Robles and back. Car is like a go kart now, but not much fun to drive that distance anymore, and I possibly carbon monoxide poisoned myself - a story for another time.
When I got up to the AMG meeting point at Paso Robles and shut the car off, the discharge protection kicked in immediately. Strange. When I left, just turned the battery on and she fired right up. Ok.
Early into the drive home, I got the big red dead battery indicator on the dash and knew I had a problem. Had my OBD2 dongle in, so checked the voltage - cruising steady at 80mph battery voltage was showing 11.5-12.5 volts. Shut off the radio and lights, didn’t seem to make a difference but I got home. As soon as I parked and shut the car down, discharge protection kicked in immediately. (it fired right up this morning after switching the battery on)
Now if I recall how the charging system works, my voltage while running should be 14V. And battery size or capacity should have no bearing on this. So I’m wondering what’s going on here. On a long drive like that, the battery should be super charged up, not slowly draining as I drive along. Do I have something drawing excess power while running, a bad alternator, or could this be battery related? I just moved the battery and wires and fuses around so maybe I have a short or something back there, that’s what I’ll check first today.
2012 P31 C63 Coupe Trackrat, 2019 GLE63S Coupe Beast
By the way, for what it's worth this is still totally fine. I consider this a permanent fix for me. Battery charges at usually 13.5-14V during driving. No issues with accessories or otherwise, no more low-voltage warnings or shutoff of any kind.
By the way, for what it's worth this is still totally fine. I consider this a permanent fix for me. Battery charges at usually 13.5-14V during driving. No issues with accessories or otherwise, no more low-voltage warnings or shutoff of any kind.
what did you end up doing, half read this post but am so lazy I am hoping I can just a get simple unplugged this or that answer haha
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I read a ton about this, and after seeing lots of BMW, Ford, Toyota, Subaru and Honda stories, eventually found a guy on a UK MB forum who said he did this on his SLK55 for a similar issue. That was enough for me.
