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Hey Guys, I've been having some issues with my E550 since July and have been at a loss. I've had this car for 5+ years, never had issues like this before, has about 122k on it now. I had to jump it in July after having driven it about an hour prior. Had the battery tested and it tested good. I work from home and I have 2 cars, this one is my "daily" so its normally used for shorter trips; grocery store, food runs, restaurant, meetings etc... End of July-mid August the car sat for about 3 weeks untouched, hopped in it and it started no problem. Last week of September for about 2 weeks I had to jump the car almost every day. Was dealing with the aftermath of Hurricane Ian, so fixing the car kind of took a back seat. I have observed the voltage outputs via the engineering menu on the dash and they seem to be within regular levels, around 12.6 while driving, around 14.2 while parked. I went ahead and put a new Bosch voltage regulator in it a couple weeks ago, old one appeared to be quite worn, but ultimately didn't fix the problem. The battery is about 2.5 years old, which is old for Florida, but still testing good. The alternator outputs seem to be in spec, battery is testing good, am I missing something here? I had to be jumped again this morning, cables were hooked up for probably 10 minutes with the other vehicle running before it would turn over.
"12.6V perfect output": ok, let's not question that
You're one lucky owner in a million with a working charge circuit.... why replace the regulator then??
You can hardly get lucky changing parts to fix a problem you have not cornered. There are hundreds of reasons a German car is acting up to get worked on.
Scanning the car and fixing many bad GND are great ideas that will surely help.
2.5 year old battery in A/C climate with frequent need of jump start... it does sound like something's wrong.
-- The main battery is "young" (not super old)
-- The charge circuit supplies non-stop
>> check/clean the main batt chassis GND brass post! It's built to act as a funnel to send salty FL mist down it threads over a steel screw... is yours oxidized or clean??
While you're looking at the main GND connection the sleepless F-SAM is being rebooted. So drain while parked will be minimized.
Speaking of which, with FL daily rain showers and salty ocean mist, look for evidence of rain intrusion at front/rear fuse boxes, footwell carpets... any swampy module can help accelerate battery drainage while parked.
Pls don't forget to post your SCAN results. This step will save you both time + money.
Thanks for the suggestions guys, I will check the grounds today or tomorrow. I have a friend who's brother has the Mercedes STAR Diag system or whatever it's called (He paid like $35k for it from Mercedes). He can be hard to get ahold of though and I don't like bothering him. If the grounds look good I'll try to have him scan it.
2.5 years is young for a battery in most of the country, but living in Southwest Florida my whole life, I don't think I've ever had a battery make it 3 years. This Bosch one is still testing good for now though.
I was reading on other forum posts that 12.6 is where it's supposed to be while driving because of the smart charging system or whatever. I also noticed that the Volt meter in the engineering menu reads about half a volt lower then when I connect a multimeter to the battery.
the voltage displayed on the car is measured directly at the battery terminals by Hyundai sensor.
If you see a .5 volt delta there must be a dirty connection somewhere - Clean things up for good measure while you're around there... free of charge is good!
.5v difference for a battery is a huge difference in charge level. You have to be careful how you compare measures: loaded vs. unloaded etc
Alternator output at or above 12.6V is perfectly good. Never anything below 12.3V with high Amps.
12.6V is when battery is fully charged up then voltage goes to float with minimal current close to 1A.
Last edited by CaliBenzDriver; Nov 3, 2022 at 12:42 PM.
Well, I just crawled out from underneath it and to my surprise there was absolutely zero corrosion on the grounds. If I didn't know better I would have thought I was looking at a brand new car underneath. I had to jump it 2 more times this morning, I guess I'll give my friend's brother a call to see if he has time to scan it for me.
Xentry wont tell you the reason you need to jump the car/battery.
However, if there are many stored faults which looks whacky, a severe voltage drop below 9.6V system voltage can cause those weird STORED ( not CURRENT ) DTC.
Your under 3 years battery life is very much the same for Jakarta/Indonesia since my city is 365 days a year hot and some days raining, but we do not see any cooler than 25C at night.
Engine bay temperature kill battery fast in Jakarta, usually 2ish years and under 3 years too.
Some cars with battery located at the trunk, can live longer from cooler working temperature and more so because local owners of high $$ cars surely have a roofed garage, so car is shaded most of the time.
My friend walked me through doing a parasitic draw test on the car. After which, we believe that the amp is killing the battery. Going to drive the car for a week or so with that fuse pulled and see if it needs to be jumped.
LOL... dang, AMP = AMPLIFIER.
I was thingking too electric, I thought you meant the AMP-erage is killing the battery....
60 milliamps is too little to FLAT your battery in even 48 hours, assuming it was at at-least 70% state of charge during last engine shutdown.
0.06 x 48 = 2.88 amps only
Ya, amplifier lol. We're going to keep an eye on it with the amp disconnected and see if it needs jumped again. If it does, we'll know it wasn't the issue. It's possible that there is another item draining the battery. Before that fuse was removed the reading was 180 milliamps, after it was 60 milliamps. My understanding is that it should be below 50 milliamps. Or maybe whatever module was draining the batter wasn't active during the test. I had to jump the car twice last week after it sat for around 3 hours after driving 10-20 minutes.
NOTE : Key is to be away from the car and car in unlock mode. Hood open.
When you want to test for parasitic draw, first is to make sure the car can go to a TRUE sleep mode. This can take up to 6 hours after car is driven but when car is parked at home and hood already open since last engine kill,
TRUE sleep mode can happen very fast, sometimes under 30 minutes after you open and close the door to take something.
To know if TRUE sleep mode has occur or not is simple. Use a test light or a voltmeter and read IG 1 post for 12V, if there is still 12V, TRUE sleep mode has not yet occur.
Relay K2 open/un-lached is what shutdown the IG1 and MRG2 or MG2 terminal/post.
Above : My car is Right Hand Drive, so dont get confused. LOL
My car has Start Stop B03 option, being a 2014 facelift. Later model or at least my facelift, pyrofuse is at battery POSITIVE terminal and not at F32. Below is F32 pre-fuse block.
Correction for yellow box above : the waiting period to SLEEP MODE, can be up to 6 hours if car just been driven.
Now, in theory : a TRUE sleep mode will happen if the computers observe that there is no more activity among the modules and is a good time to SLEEP.
If any module/s still not finish with its/their business/task or in a faulty mode which it/they can not sleep or do deep-standy by, TRUE sleep mode may not happen.
So easiest for now is to make sure TRUE sleep can happen.
Have fun troubleshooting.........
Still I would think that video I linked to test your battery should also be done.
Last edited by S-Prihadi; Nov 7, 2022 at 02:21 PM.
The total draw dropped by 60 miliamps when I pulled fuse 67, which is for the Harman Kardon amp
I was thinking about this post this morning and realized that I must have been half asleep when I wrote this ... 180-60=120, not 60 So far so good on that fuse being pulled though.
I have observed the voltage outputs via the engineering menu on the dash and they seem to be within regular levels, around 12.6 while driving, around 14.2 while parked.
Not to be picky, but those numbers have to be backward. Voltages shown in the cluster should be (+/- .1V)
12.8 V when new and recently charged and disconnected from the cars --> Unloaded. Of course, use a voltmeter since it is disconnected.
12.x V when connected with the car and the computers awake and draining a bit. --> Loaded
14.x V when regulator at its best --> Do not touch the charging system, It cannot get any better.
12.6 V when the regulator nears its end life. Anything below and you will be jumping the car more often, and likely burn something at some point (we all make mistakes). Time to look at the alternator/regulator components.
Now to the battery drain, does your car have KEYLESS GO? If it does, do you usually press close twice using your keyfob, or only once? Check your habits when closing the car: once locks the car, twice locks the car and shuts down KEYLESS-GO. Keyless go is known to drain the battery on other MB's, so watch for it as well. For MY2011-W212, the fuse for KEYLESS-GO should be 74. Keep it in mind in case pulling 67 did not fix the issue.
Not to be picky, but those numbers have to be backward. Voltages shown in the cluster should be (+/- .1V)
12.8 V when new and recently charged and disconnected from the cars --> Unloaded. Of course, use a voltmeter since it is disconnected.
12.x V when connected with the car and the computers awake and draining a bit. --> Loaded
14.x V when regulator at its best --> Do not touch the charging system, It cannot get any better.
12.6 V when the regulator nears its end life. Anything below and you will be jumping the car more often, and likely burn something at some point (we all make mistakes). Time to look at the alternator/regulator components.
Now to the battery drain, does your car have KEYLESS GO? If it does, do you usually press close twice using your keyfob, or only once? Check your habits when closing the car: once locks the car, twice locks the car and shuts down KEYLESS-GO. Keyless go is known to drain the battery on other MB's, so watch for it as well. For MY2011-W212, the fuse for KEYLESS-GO should be 74. Keep it in mind in case pulling 67 did not fix the issue.
From what I have read on other forum posts, the W212 has a smart charging system of sorts for improved fuel economy and is designed to run at 12.6V when driving. I guess it never actually charges the battery to 100% and the car is known to eat batteries as a result. I don't think it really matters in SWFL though because our climate eats batteries anyway. It will run at 14+ volts if the battery gets low until it reaches a certain charge level, some were saying it's around 75%.
I do have keyless go and always use the sensor on the door handle to lock the car.
My main point was that "there is no way a battery shows 14.x V when is not being charged".
The maximum voltage for any high-quality automotive battery in the 12V range is 12.8V when new, charged, and w/o any electric load. Those batteries are usually 6 cells of 2.1V --> 12.6V +/- error.
It is true the W212 platform has a smart charging system that will try not to overcharge the battery once it is charged. That is, 12.6V only if there is no load in the vehicle, which means the car is basically OFF. If you drive with AC on, and anything else on: radio, lights, accessories it will be above 12.6V for quite a while after starting the engine. If I recall correctly, the cluster voltage must be activated when the car is OFF, then start the engine. Yours have to be higher than 12.6V for at least a few minutes.
The ECU request 12.6V from the alternator when it has measured with main Batt sensor that the battery is fully charged. ("IB" near 1Amp).
The ALT always supplies 100% of the car power during drive time. Battery is either actively charging or idle standing-by, never contributing power in normal driving outside of ECO cycle.
Last edited by CaliBenzDriver; Nov 10, 2022 at 06:46 PM.
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So far so good on that fuse being pulled though.
