Yet another battery drain thread (2003 E500)
Thread Starter
Senior Member
Joined: Dec 2005
Posts: 290
Likes: 9
From: Atlanta
2002 G500, 2007 CLS 550, 2018 GLC 300
Yet another battery drain thread (2003 E500)
For the past few weeks I had been getting the "electrical consumers switched off" message. What has been done in the past week:
1) New main battery
2) New auxiliary battery
3) Fully charged both batteries
3) New battery control module
The warnings persist, and the battery loses charge overnight. About twice a week I have to recharge the battery to start the car. With the engine on, the voltage is 14.1 volts at the battery. I tried to do a current draw test by installing the multimeter in series between the disconnected negative battery cable and negative battery terminal, but it reads between 0.00 and 0.01 milliamps, so I have no faith in that method. do you guys know how to properly check for current draw on the W211? I have checked for dome lights, vanity visor lights, bluetooth puck are all off or disconnected. I also sat in the car after arming the alarm to listen for relays / motors that may still be active. that I have heard that the seat control modules can drain the battery. Any suggestions?
1) New main battery
2) New auxiliary battery
3) Fully charged both batteries
3) New battery control module
The warnings persist, and the battery loses charge overnight. About twice a week I have to recharge the battery to start the car. With the engine on, the voltage is 14.1 volts at the battery. I tried to do a current draw test by installing the multimeter in series between the disconnected negative battery cable and negative battery terminal, but it reads between 0.00 and 0.01 milliamps, so I have no faith in that method. do you guys know how to properly check for current draw on the W211? I have checked for dome lights, vanity visor lights, bluetooth puck are all off or disconnected. I also sat in the car after arming the alarm to listen for relays / motors that may still be active. that I have heard that the seat control modules can drain the battery. Any suggestions?
Last edited by foreyes; Apr 6, 2014 at 08:21 AM.
Out Of Control!!
Joined: Aug 2010
Posts: 12,516
Likes: 628
From: Charlotte NC area
2019 WS222 S450 4-Matic / 2007 W211 E350 4Matic (Sold) / 2008 X164 GL320 CDI
If you put an ampmeter in series with the battery and it is showing no draw, either you do not have it hooked up or set correctly or it is broken.
I good test would be turning on something and making sure it reads what you expect.
I good test would be turning on something and making sure it reads what you expect.
Super Member
Joined: Feb 2007
Posts: 530
Likes: 109
From: Atlanta
2016 AMG GTS
I/m currently having the same issue with new front and rear batteries. Doing some tracing with a multimeter inline, 6A draw right now but rear trunk lights come on and courtesy light which is throwing off the reading, doing some more diagnosis today.
Super Member
Joined: Feb 2007
Posts: 530
Likes: 109
From: Atlanta
2016 AMG GTS
For the past few weeks I had been getting the "electrical consumers switched off" message. What has been done in the past week:
1) New main battery
2) New auxiliary battery
3) Fully charged both batteries
3) New battery control module
The warnings persist, and the battery loses charge overnight. About twice a week I have to recharge the battery to start the car. With the engine on, the voltage is 14.1 volts at the battery. I tried to do a current draw test by installing the multimeter in series between the disconnected negative battery cable and negative battery terminal, but it reads between 0.00 and 0.01 milliamps, so I have no faith in that method. do you guys know how to properly check for current draw on the W211? I have checked for dome lights, vanity visor lights, bluetooth puck are all off or disconnected. I also sat in the car after arming the alarm to listen for relays / motors that may still be active. that I have heard that the seat control modules can drain the battery. Any suggestions?
1) New main battery
2) New auxiliary battery
3) Fully charged both batteries
3) New battery control module
The warnings persist, and the battery loses charge overnight. About twice a week I have to recharge the battery to start the car. With the engine on, the voltage is 14.1 volts at the battery. I tried to do a current draw test by installing the multimeter in series between the disconnected negative battery cable and negative battery terminal, but it reads between 0.00 and 0.01 milliamps, so I have no faith in that method. do you guys know how to properly check for current draw on the W211? I have checked for dome lights, vanity visor lights, bluetooth puck are all off or disconnected. I also sat in the car after arming the alarm to listen for relays / motors that may still be active. that I have heard that the seat control modules can drain the battery. Any suggestions?
multimeter common going to negative battery clamp, multimeter 10A connection going to negative batter terminal, thats giving me real readings.
Thread Starter
Senior Member
Joined: Dec 2005
Posts: 290
Likes: 9
From: Atlanta
2002 G500, 2007 CLS 550, 2018 GLC 300
Thanks, N_Jay and realien, that connection gave me a reliable reading. After the car was locked, there was a consistent 1.5 amp draw. Enough to drain the battery overnight. When I pulled the fuse for the passenger side seat control (fuse 23 in the dashboard fuse block), the draw dropped to 70 milliamps (0.07 amps). For now I'm just going to leave the fuse out. Will replacing the passenger seat control module fix the current draw? I was reading on the W203 forum about similar issues, and a simple re-wiring mod that fixes the current issue. Has anyone done this on the W211?
Last edited by foreyes; Apr 6, 2014 at 04:12 PM.
Newbie
Joined: Nov 2007
Posts: 14
Likes: 0
2004 E500
I have also been having discharge issues, with a new main battery and an aux battery that is about 2 years old. I would get the "convenience functions unavailable" warning most mornings, and a dead battery after 2 days of no driving. I noticed that my phone would remain connected to the car (via a bluetooth puck #67875855), and then confirmed the puck would never go to sleep and the blue light would flash continuously. The puck works fine otherwise. I can disconnect the negative terminal for a couple of minutes, reconnect, and then the puck would disonnect properly and go to sleep, but only and for a few days, and then it is on constantly again. I unplugged and removed the puck, but the problem still exists. Yesterday I noticed that my driver's side seat control would not work with the key in any position, and I had to open the door to get the control to work. The headrest control would not work at all, although it worked fine the last time I used it. What are the symptons of a dead seat control module? Also, does anyone know what fuse controls the puck, which I suppose is the same plug where a telephone cradle could be plugged in?
Newbie
Joined: Aug 2007
Posts: 14
Likes: 1
2014 S550
Similar Problem
I have been having the battery going totally dead, when I hooked up the amp meter I was getting about 1.5 amps draw and could not find the issue. I unplugged every fuse but could not locate the draw. What seemed to fix it for me was replacing the battery in the Mercedes cell phone that is the arm rest. I think the phone system never turned off and it was always trying to charge the phone and this could have been the cause. I have not had the dead battery issue since I replaced the cell phone battery.
How ever I still get the convenience warning most of the time sometimes as soon as I start the car and sometimes after driving for 30 minutes. I am thinking that my main battery may be bad from all of the times the it ran down to nothing. Also I think I see the dash board lights flicker sometimes which has me thinking that there could be an intermittent alternator issue.
How ever I still get the convenience warning most of the time sometimes as soon as I start the car and sometimes after driving for 30 minutes. I am thinking that my main battery may be bad from all of the times the it ran down to nothing. Also I think I see the dash board lights flicker sometimes which has me thinking that there could be an intermittent alternator issue.
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Out Of Control!!
Joined: Aug 2010
Posts: 12,516
Likes: 628
From: Charlotte NC area
2019 WS222 S450 4-Matic / 2007 W211 E350 4Matic (Sold) / 2008 X164 GL320 CDI
Killing a battery, especially an AGM battery is very hard on it.
Flickering could be the alternator/voltage regulator trying to constantly charge a bad battery.
This is a good way to fry one or the other (or both).
Flickering could be the alternator/voltage regulator trying to constantly charge a bad battery.
This is a good way to fry one or the other (or both).
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Newbie
Joined: May 2014
Posts: 1
Likes: 0
03 E50
My 03 E500 battery trouble
I've had an issue with my battery dying over night for a few weeks. I changed the battery in the trunk and still had an issue a week later. I took it to my mechanic avoiding the dealer and was told to replace the battery control unit in the trunk .hat resolved my issue for only a few days with still getting the non starts in the morning and error codes. I finally broke down and took it to the dealer and they stated a fuse blown the relay and auxiliary battery under the hood. Then stated it was the passenger seat that caused the problem hitting me with a $900 charge for the fuse, relay and auxiliary battery. Any options for repairing without taking it to the dealer?
