DWP

The battery unexpectedly drained on our '03 E500 sometime between 6:00 PM Saturday and noon Sunday. Is this a known behavior, or am I the lucky discoverer of a new species of W211 electrical gremlin?

The car is a 9/02 build that we've had since 9/03. We haven't gotten any indication of low-battery problems, including when we drove it on Saturday. It fired right up and didn't display any warning lights or malfunction messages. The car was in a closed garage overnight and the outside temperature didn't go below 45 degrees F or so. I took the key out of the car when I parked it last night, closed all the doors, etc. When we went to start it at noon today is was totally dead - didn't respond to the remote opener, didn't respond to the key in the ignitions, trunk opener wouldn't work - had to open the trunk with the metal key and manual release. The battery showed 4.6 volts when I measured it.

Right now I've got a trickle charger on the battery (with the positive lead disconnected) and it's showing that it's charging at the maximum rate (8-amp). Even if I can charge the battery and start the car tomorrow, though, whatever drained the battery overnight will presumably do so again tomorrow. It's going to the dealer, for sure, but is there anything I should be aware of or can do in the interim?

Randy B

DWP, At the risk of sounding like a Wise A$$; Is it possible you left the headlights on in some position other than off or auto?? I have found that occasionally I can turn the switch to far one direction, and sometimes have half the parking lights on, or all of them if I go the other way. Otherwise I hope this is a fluke for you. I too have a 9/02 build and have not had that problem.

PSquared

A similar thing happened to my pre-NAV car. I parked it in the garage and locked the doors. When I came back MINUTES later to get something out of the car, I couldn't open it with the remote because the battery was dead. After it was jump-started, all sorts of warning lights came on, and they had to replace the central gateway to fix it. So, it's yet another electric/electronic problem in W211.

etenn

Had the same thing happen a few weeks ago. Returned from out of town to find the battery dead. Had to use the little metal key to get in.

Called MB Road assistance. They sent a dealer truck out to jump battery. Took it in and they diagnosed it as a bad BCM (Battery Control Module) located in the trunk by the spare tire.

They installed a new one and no more trouble.

5thbenz@35

I had the exact same thing happen to me on my 03 S430 the day after I got it - the problem was I wasnt used to taking the key out being used to my BMW (key was not turned to any on position just left in the ignition in the off position - that will drain it) - I also had to use the metal key just to open the trunk...what a pain - I just jumped started mine and that took care of it.

yabenz

Can you tell me how much you paid for the bcm ? I have the same problem caused by a leaky trunk that got the bcm wet in my 03 E500 and they want $730 ffor the module! Yikes Hopefully I can find it on the net cheaper!

konigstiger

Part # 2115408645 (for comparison shopping, parts.com $365.70)

kfourymerc

Hi All,

I had the same problem. I would send it to the shop and the problem never went away. I changed 3 new batteries, they diagnosed the whole car and nothing showed up. It kept draining no matter what I changed or did.

However, If the problem is not from your Alternator or any other problem from the car, then have the SBC system checked. Mine didn't have any warning message but my mechanic told me the pressure of the SBC system was low and it needed to be changed. It costs quite a bit. I believe prices will change from region to region. I live in Lebanon, in the Middle east. I was able to buy a used SBC system. So far so good. No more drainage problems.

cheers

AMGAffalterbach

If you take it to the dealer, as I always seem to advocate, they will load test the battery for you for free and let you know whether or not it is a bad part. They should NOT charge you for this. When I bought my car a few months ago used, I had this done immediately to make sure that it would crank properly for unpredictable Colorado weather.

kfourymerc

Hi,

Please explain what you mean by unpredictable weather? Does the weather have anything to do with the car not starting or the battery draining? I realised that in really cold weather the car wouldnt start, or during any weather change it gets colder, the car will also drain.. How is this possible and whats the cause and solution?


Thanks

AMGAffalterbach

Although we are at the dawn of the summer months and predictable forecasts of hot and dry weather, in autumn and spring temperatures can experience massive swings and the skies can change in an absolute instant. Snow or hail might line the streets when one goes outside after a day of work when the morning was of clear skies and high temperatures. This is largely due to the Rocky Mountain range and subsequent weather systems.

I have never had an issue with a battery or car due to weather, but I know many who have due to plummeting temperatures. This is caused by the battery itself and tends to be a problem in older or malfunctioning units. Solution - load test it at a dealer to verify that it is the problem and replace it.

lsbrodsky

kfourymerc, We have a 2009 E350 that has run the battery down twice in the past two years. The first time the dealer found nothing wrong. The second time he found a faulted Satellite radio module and said that it could have resulted in a current draw that killed the battery overnight. Not convincing to me.
I have been logging battery voltage twice per day for the past two weeks and have not seen the problem recur. These days many people seem satisfied to hook up their car to a battery maintainer, but I am reluctant to take that path for a car that is driven every day, even if it is short trip driving.
So yes, I have a problem with my battery and no, the dealer has not found a solution. This is a fatal black mark in reliability, in my book.
Larry

TUngpiyakul

I have the same problem on my 2004 E320 since about May 2004. The first time it happened, I changed the battery. After 2 weeks, it happened again. This time I disconnected the battery, charged it up, reconnected and measure the voltage every day after work. Nothing happened until about 2 weeks later. I bought a clamp on ammeter on and it was discharging about 2.2 amps after two hours of leaving the trunk lid open. I pulled all the fuses (one at a time), but the draining never stopped. I charged the battery overnight without disconnecting. In the morning, it still drew at about 2 amps. I went to work, came back home and it was still draining the battery. I did this for 2 – 3 days, but the draining never stopped. So I disconnected the battery and did this over many times before I took it to the dealer (while the battery was draining). The shop said it stopped draining so they could not find it.
I bought a quick disconnect battery terminal and put it on the negative terminal and have been checking the draining every day after work. If it does, I disconnect the battery overnight. The period now is reduced to about a week. I plan to wait until it drains almost all the time before I take it to the shop again. Between now and then, does anyone have a suggestion?

vettdvr

Is there a more current part number?

konigstiger

No, current part # is 2115408645.

vettdvr

I am still stuck 1200 miles from home with this problem I have two new batteries and same issue in my2003 E500. Holiday dealer is short handed and told he may not be able to do anything for me. Wow,, isnt' that exciting. I will have to jump the car and drive a limp dog 1200 miles home. The 1st time last week before Christmas I went to start and totally dead and 5 Vin the main bat. I slow charged and all was well for 2 days then repeat. But this time I get the Bat symbol in the FSS and convience items off. Finally dealer opens after christmas then tells me he may not be able to do anything until mid January. I have to be home on 1/2 with the car.

I am now beyond any rational considerations on this car because the power steering failed shortly after I left town. Two weeks before I had the steering column tilt repaired and 2 months before that both front airmatic struts and brakes rotors all around.

Is there any quick bullet I can shoot here to get this car where I can drive it home if the dealer can't help. IF I have to overnight on the 1200 mile drive and disconnect the battery I have to leave the car unlocked or the alarm will trigger off the secondary battery. I can't even begin to tell my frustration on this car. It has been maintained totally by the MB recommendations for all fluids parts etc and I can't even make a trip from home without stopping in a shop for repairs.

Can anyone offer suggestions? Seat module? Where is it how to unplug to try ? How can I test the battery control module? How about the aux battery relay? I surrender I am having way too many issues on this car.

konigstiger

Have you checked your email?

TUngpiyakul

Originally Posted by vettdvr
Can anyone offer suggestions? Seat module? Where is it how to unplug to try ? How can I test the battery control module? How about the aux battery relay? I surrender I am having way too many issues on this car.


Please also share the method of testing seat control module, BCM, relays, etc. with me – pretty, pretty please. I think I know enough to be really dangerous.

vettdvr

Yes but I haven't found anything. My direct email sent to you

TUngpiyakul

Yes, please

plasma

I know this is a few years old, but my 2003 E320 just had battery drain over night. The Stealer discovered it was the seat module and wanted over $1000 to replace it. I bought the part for under $180 and replaced it myself. It only took 1 hour and very easy.

TUngpiyakul

Thanks for the info. My was the Battery Control Module.

FunkTron

For my situation.....I won't lie, I had the dang fogs on. I walked out to a dead (3.2v) battery this morning. Hooked up some jumper cables to the truck and saw the fogs come on immediately, albeit dim. Turned them off and got the car started after a bit of charging.
I hooked up the battery to the battery maintainer for the time being.

Lesson learned.

As a side note, if you google "dead battery mercedes" there are like 2 dozen threads with nothing but people who can't figure out how to use the mechanical key to open the trunk.

plasma

Like everything else on this car, I'm sure my BCM will go out as well. Did you have it replaced by the dealer or did you DIY?

daveck2

I too have had this drain issue and the BCM replacement helped for about two days. Funny think is, I never got the Red Battery warning, just the drain overnight, but when I replaced the BCM, I immediately got the red battery warning, but the drain problem when away. Three days later, the red battery warning went away and my battery drain problem returned. I have a second battery in my trunk to boost my car on demand I guess I'll check my seat control module next. I've owned BMWs all my life but this is my first Benz (maybe my last).

Dave

2003 E500