LanceA

StockC43, I dont think that's the problem in this case. Considering it was fine one day and kaput the next, something has to have gone bad or shorted.

Critter

12.2V reading on a sitting battery means it is about 60% charged or has a bad cell, this in itself will cause drain as the car sits.
Diagnosis- unhook the battery from the car and put on a trickle charger for a few days or a regular charger on low charge for 24 hours. Unhook and then check for bat voltage, should be high 12.8-13.1 depending on the charger used. recheck unhooked bat after 24 hours should be reading 12.6-12.8V if it is fully charged and holding that charge.
as stated above make sure there are no phones or radar detectors or any non factory electrical device hooked up, if there is, then disconnect the device for a few days.
Common battery issues are from aftermarket devices hooked in the cars electrical system and not allowing the car to power down, also when exiting the car use the fob to lock it, watch for lights flashing or as my E does it beeps at you 3 times as well as flashing of the lights.

turbo97se

Weird ... mine sits for 3-4 weeks at a time sometimes but fires right up ... not even a battery low voltage! I'd be interested to know what this is. There should be tests in Mercedes DAS to help isolate the issue. The only issues I have had in the past were when I left the DAS hooked up overnight it would drain completely dead and also if the battery terminal was loose.

stockC43

Easy enough to test though. V60's won't work anymore anyways since they were analog so there no need to have it plugged in.

LanceA

I have spent the afternoon going around in circles. Pulled every fuse in the 5 locations of the car. The battery continued to drain. Darn.

From reading all the posts on the forum here and elsewhere, I guess its coming down to three probable causes:
1. Software
2. SAM's
3. WhoTF knows!!

Guess I will head out to the dealership in the morning.

LanceA

After all the hassle…and $1000+ of man hours…..the problem was the SAM worth $89.

Need to find a Merc repair shop!!

GREY GHOST

Hey Guys I am going through the same thing with my 2004 S500 it has gone through 3 Alternators in 1 year, I was told to replace my genuine MB battery as that could be causing me to eat alternators. I did not as it tested fine. Well not a month ago I got the dead in the morning suprize and thought maybe they were right, battery was at like 5.5 volts. I replaced it with a brand new aftermarket and everything has been perfect until this morning when the same thing happened to my wife out of town. AAA came and jumped it and said this new battery was at 5 volts. I checked the alternator when I installed the new batt and it was fine, and we always got the error GO TO THE WERKSHOP BATTERY NOT CHARGING when the alt would go out, so I do not thing it is the alt. The first time it happened I thought the wife left an interior light on but if that drained the battery overnight then I figured the batt needed replacing anyway. Now I am thinking I have an intermittent drain. WHAT IS A "SAM" people talked about here?... So at this point do you think I should bring it to my medic and plug in his computer and it may have a record of the issue, or do you think it would not code this. HELP IS MUCH APPRECIATED as it is freaking 0 outside and not fun to be white knuckling this issue. Thanks!

LanceA

Hey Grey!

A SAM is a Signal Acquisition Module. Generally its the block that holds all the fuses.

I would first check the fuses and determine if any of your services have the fuse set in the permanently on slot before checking the SAM's. I know mw W211 has that capability. Not sure about the S class.

GREY GHOST

Thanks Lance, anyone know if this kind of thing would ever show up as a service code or the like if I had the computer checked by my auto medic?

MJ50

not sure if SDS can detect where the draw is coming from...

GREY GHOST

So I charged the battery overnight in the car and my BCS10B Smart Charger from Black & Decker I have used on countless batteries over the years showed a new message this morning: Overtime Condition.

From the webpage it says:
Q: What is the “Overtime Condition”?
A: The Overtime Condition indicates that the battery has not accepted a charge after 18 hours of continuous charging. The battery may have internal damage and needs to be replaced. Have the battery tested by a professional battery technician.

So I had to unplug and replug in the charger and the battery was at about 11v now and it is charging up to almost green at 13.5 within 10 minutes. Tech support was no help in asking about a drain causing this error, but it is obvious I have a drain.

The was car unlocked and I DO NOT HAVE ANY KEY FOB with me so no unlock or ket in the ignition. I was sitting there I heard nothing after the door closing system closed the door, so no drain there, and checked my bluetooth module and it had no lights flashing. When I turned on the headlights I could hear some kind of fan or something behind the dash and the radio has some really loud pops and tones for a second, that seemed strange to happen or even be able to turn it on when just turning on the headlights, When I turned on the radio the Mercedes bluetooth upgrade I put where the original phone was plugging into the factory phone harness, started flashing the blue LED. I turned off the lights and the stereo turned off, but the bluetooth light kept blinking after the lights and stereo was shut off. It has been about 30 minutes and the charge is up to 14.8 and the Bluetooth light is still flashing.

The day before this dead battery happened out of town, as my wife was leaving I synced my wife's iPhone to the system for her trip and it acted funny not working correctly like not being able to answer using the steering wheel but rang through the stereo. Now after the battery dies and she got a jump from AAA and was on her way home her iPhone started working with the system.

It has the bluetooth light still flashing after 45 minutes. I know I was able to use the phone before when the car was off while still on a phone call, so it may be normal for a little while but it has picked up my audio when I was in my house shortly after parking in the past.

This dead in the morning has happened 2 times randomly over the last month and I replaced the battery last time it happened thinking it was the battery. I charged the original battery I took out and it took a 14.9 charge and held it for weeks, had it checked at an auto parts store and they said it was fine under load.

OK UPDATE: The Bluetooth stays flashing and if I just open the door I can turn on the stereo with no key. Is this supposed to be able to be powered with no key? Also with my driver door open I would try to turn it off and it would come back on again and again? Anyone know what Replay or Polyfuse I need to pull to reset this? I think this is the issue with it not turning off the BT.

Pinoi Ryder

i have replaced all battery.. still getting battery drain.. mostly after about 9 hours.. i have bluetooth OBD2 installed and been monitoring the voltage, it has been putting out 14.8 volts.. is there a way to self test the battery control module?

mattrox1221

If anyone has experienced the issues expressed on this thread and been able to figure out the cause of the constant battery drain please shed some light.

I've had the same symptoms.

The red battery fault warning. The car would still start, although sometimes struggling to turn over if left to sit for a day. This went on for months.
I thought it was just the battery going bad.
One morning car is completely dead after sitting for 3 days.
Replaced battery.
Same thing, dead after three days.

The car is at the dealer now but they are telling me nothing is wrong with it. I told them to keep it and keep looking, theres definitely something wrong.


For any and all of those that have dealt with this issue some specifics on which module went bad or any other helpful information that I can relay to the dealer would be extremely appreciated.
Thanks for your help.

365v

First time over a year ago at the airport after several days. Both batteries dead. Thought maybe my fault could have left interior light on. Jumped car, drove home and charged both batteries. OK until recently. After sitting in my garage 3 days both batteries dead. Charged both batteries and they checked OK, charging system OK. Checked bat voltage for next 3 days OK. Drove for few days then checked battery voltage. Checked OK ,next morning volts low charged battery and checked OK. Parasitic drain someplace- any Ideas?

Flyboy777

I have a CL500 yr 2000 , and my battery goes Dead after24/32 hrs .
check battery it’s good checked Alt good , put amp meter and checked drain on rear window control unit under rear pax seat
And seamed to draw excess amps . Or could it be window regulator throw unit?
any body have same problem or ideas?
thanks

hachiroku

i had similar draw on my vehicle that i battled with for about a month or so. my battery would literally be dead from full charge either over night or after a weekend in the garage. finally got fed up and brought it to my local Mercedes specialist. after dropping off my car numerous times for diagnosis, they finally were able to find the draw. the battery draw was random and sporadic and was attributed to a failing central control module which was keeping the MOST network active at random times at random intervals. since it was random they would log a draw and it would suddenly disappear during diagnosis. throughout an entire 3 day span they had to randomly check if a draw was present to continue checking off each module for fault.

per technician, this is not a common issue and i was the first they had ever replaced. but as with anything on vehicles with large amounts of technology, the more tech, the more things are able to fail.

Fountain35

Do you hook up a battery tender under the hood or the rear battery?

Flyboy777

Thanks for the info but I have a MB215 CL500 do you think it has a CCM?

drzcrazychulo4u

Hi everyone, so ive done several searches all over the internet and cant find the help i might need. I have a 2007 mb e63 amg and i have a battery drain as well. i have tired everything and i dont know what to do. took it to several "mercedes mechanics" they all say the same thing ,change the battery but i have put already 3 brand new batteries in and it still drains overnight some take longer maybe 2 days at most. i have done the parasite check, where i manual closed all doors and hood and trunk and checked all fuses after the car being off for some time. 95% of fuses still had current (staying on)! Anyone have any idea why that is??

equitiesguy

I've read most of this thread, and for this type of parasitic draw save yourself the time and energy and just pick up a thermal imager (or borrow one off someone). Leave all your doors open, trunk and hood as well, and when the car shuts off in 15 minutes scan the entire car looking for a heat source.

hachiroku

you guys are blindly ignorant to my post aren't you...if the MOST system is NOT SLEEPING, ALL modules stay on drawing power

you need a Mercedes Master Mechanic to diagnose MOST system issues.

MacMan

I was having the same problem. Turns out it was the fuel pump. I know the last place I would have thought of. Worth a look see.

gbaran123

I had the same issue on my 2006 E350 4matic. Turns out Fuse #8 was the culprit and I narrowed down to the Theft Module drawing 5.5amp all the time. Unplugged the module and draw went away. Module is located next to the passenger side back seat.

Lyricsmoe

Mines worse, I bought my w220 s320 cdi from a friend's uncle last year and the key fob never worked. Yesterday I went on YouTube and learnt how to repair it and it's working perfectly fine. locks and unlocks, even does the full window power up and down thing. Now here's the problem. Before then battery only stays two nights and it's flat, I have to drive it almost everyday but now it got flat after I fixed the fob, had to take it for a quick spin to charge. It's morning now and I have to get a jumper. Anyone please help.

hatemy350e

I just bought a 2006 e 350. To say I didn’t do my homework on this pos before I bought would not be totally correct it was posted as 2007 it is a clean as vehicle after market rims and only 135000 miles. I got scammed bc I didn’t even notice the 2006 on the title. I never purchased a car before and I I thought I gotta deal for four grand the drive chain is vibarating at 2100 rpms and now this battery bs. Something is wrong with electrical stuff bc it started saying brakes were not powered and I had to press the brake pedal fully but that ain’t do anything and so I just cut of and on the car few times it went away.. I changed batteries and it’s lasting less and less .. my dad left me a lil money that I have spent on this car and a 530 I for my daughter .. idk wtf to do