benz_addict

2004 S430 4matic

Car battery dies overnight

So far I have replaced:
Alternator (2 times)
Battery (2 times)
Replace overhead control panel (sunroof switch)

Over night disconnect test:
Disconnected front seats - still dies
Disconnected front left and right door control modules - still dies
Disconnected the COMAND (unplugged it from the back) - still dies
Disconnected the PSE pump - still dies
Removed Audio fuses - still dies
Disconnect power to front left SAM - still dies
Disconnect power to front right SAM - still dies
Disconnect power to rear SAM - still dies

Can anyone help me out? Thanks!

tusabes

Get a battery brain t3 from Amazon

It's a keyfob controlled battery disconnect . Exit the car and click the key fob and it will completely stop the battery drain

Zach8131

Do you have a built-in radar scanner/hammer by chance? I had one installed on my car and it sucked my battery clean because of an exposed wire.

hvacdude

Battery drains on our cars are often a result of the CAN bus system not going to "sleep" after the car is shut off. Several things can cause this to happen. In my case, I had installed a after market audio component that required me to disconnect the CD changer in the trunk. The CAN bus would not go to "sleep". The battery would drain over night.
I ended up installing a relay that opened the command circuit CAN wires at the CAN bus strip {under the drivers side floor panel}. It stopped the command circuit from communicating with the central gateway when the car was shut off. This fix stopped my battery drain and It has been all good for about a year now.
If I was you I would try this: After you shut the car off for the night, disconnect the 2 wire connector plug on the central gateway. That 2 wire plug is the power source for the central gateway. The central gateway is under A plastic panel below the the dash on the drivers side {USA car}. See if your battery drain goes away after doing this. If it does, that means the CAN bus is keeping the car from going to "sleep'.
If the battery didn't drain overnight and the car starts up; you will have error messages from the central gateway being unplugged. Plug it back in and they will go away after a short while. If the CAN bus is causing the battery drain, a STAR machine will tell you what CAN circuit is faulting. You can trouble shoot the faulting circuit or do what I did: Just kill the Central gateway power supply with a 12volt, normally open, single pole single throw relay. Break {open the circuit} of either one of the 2 wires that power, or ground, the central gate way. I powered the coil side of the new relay through the aux fuse in the fuse box {on the drivers side, under the hood}. You'll have to run a wire from the fuse box, into the car. In my case the previous owner had a wire installed that powered a remote radar detector that no longer worked. I just used that wire for my relay. If you don't want to run a new wire, tap into the cigar lighter for 12volts when the ignition is turned on. When I made this fix, I wired the relay to only break the command circuit at the CAN buss connection bar under the driver side floor board. I found out {after forgetting to reconnect the central gateway} that disconnecting the power source to the central gateway stops the CAN system from draining the battery. If you search through my posts you will find what I did to address my battery drain issue, along with pictures I took when I was working it out. Hope I was of some help to you, keep us posted as to what you find and good luck on fixing your car. Here is a link I posted about it: https://mbworld.org/forums/s-class-w...ery-drain.html

hvacdude

Another known battery drain issue on the W220 is the alarm system battery. The battery goes bad and draws power from the main battery trying to charge it. It's under the fender liner above one of the front wheels. I don't remember which side of the car it is on. I would try disconnecting the central gateway first, as I described in my previous post. If that doesn't work, try disconnecting the alarm battery next. As a temporary fix, you can install a simple battery disconnect switch on the negative post of the battery located in the trunk. Turn the switch off when you park the car overnight. I bought one from Harbor Freight for under $10. I kept it connected even after fixing the battery drain. It comes in handy when working on the electrical system or putting the car in storage.

danielkon

I had a battery drain problem, for me it was that the compartment under the cd changer in the trunk flooded with water! There is a whole bunch of electronics down there and it was all completely submerged. I was also getting crackling and popping sounds from my speakers and the trunk carpeting was always moist.

After removing all the water, probably over 2 liters it, I was literally scooping it out with a cup. The battery stopped draining after that!

Of course I investigated as to why the water was getting in and found out that it was the seal around an aftermarket taillight that I bought, it degraded and the water would just come through slowly building up and flooding my ride.. Been good sine though

Zach8131

You're so lucky that it didn't fry your entire car! Lucky lucky lucky! congrats on fixing the battery drain.

2oCLKoo

I just used the drain plug under the CD changer.
my battery was drained the night I saw the water and left it thinking that it had been there long enough what was done was done. I just bought the car last week. Put in a brand new battery and after seeing the water the drain happened. Fingers crossed pulling the drain and cleaning the water and unplugging some of the electronics will help with draining issue.
I will keep posted. Sorry if old post. Didn't check the date.

wallyp

We're not sorry to see you do some research to solve your problem yourself! Good job!
Now you get to research how to dry and repair drowned electronics...

raez77

Same problems for my car. Can you explain it please

ChrisHimself

Know where ALL your fuses are and what they do, you're going to test every single fuse with the battery connected and the key out to check what is drawing power. Connect all your accessories again and run through the system. I have seen pretty much everything, COMAND, SOS, seats, etc develop a fault and parasitic draw the battery down overnight. Once you identify which module, you can repair/replace or just disconnect them depending on how far you want to go with this. This toy makes it so you don't have to hunt and peck for the leads at the top of the fuses and it makes it a breeze to go through every fuse through the various boxes.

raez77

I checked all 4 DCM
it takes 10ma the driver door module and real right side module.
and i checked SCM no error
checked over head panel no error
checked command it have 70ma draw
checked pse no error
head light checked no error
glov box checked no error
right and left side mirror all checked no error
trunk checked lights no error
tail stop light checked no error
still using 700 ma
what is remaining?to check