The mysterious battery draw
#1
Member
Thread Starter
The mysterious battery draw
If my 2009 W221 is parked for 2 ~ 3 days, the battery is flat.
The battery is only 2 years old and I tested it and it checks out fine
I haven't added any electric "stuff"
So now I took a "scientific approach:" I bough an amp-meter that can record it's readings over time.
Here is what I found: After 15 ~ 30 minutes the car "shuts down" and current draw drops down to an average 50 mA (which is good).
But then there are times when the current draw suddenly spikes up to 3.3 Amp and overall the car draws an average of 365 mA (which is too high)
My best guess is that the ECU "wakes up"
The chart below is for a 45 hour period, starting 30 minutes after I shut off the car
Any good ideas?
The red line is the average current draw
The battery is only 2 years old and I tested it and it checks out fine
I haven't added any electric "stuff"
So now I took a "scientific approach:" I bough an amp-meter that can record it's readings over time.
Here is what I found: After 15 ~ 30 minutes the car "shuts down" and current draw drops down to an average 50 mA (which is good).
But then there are times when the current draw suddenly spikes up to 3.3 Amp and overall the car draws an average of 365 mA (which is too high)
My best guess is that the ECU "wakes up"
The chart below is for a 45 hour period, starting 30 minutes after I shut off the car
Any good ideas?
The red line is the average current draw
#2
MBWorld Fanatic!
Keep in mind that these vehicles are rather complex even for today, and they have many control modules on several CAN networks, and one device can request a wake up signal on the CAN network and cause several devices to power up.
Fortunately, they do have a few ways to diagnose these issues with the factory Xentry Dianostics tool by querying the Battery Control Module. It will tell you the previous devices that caused the system to wake up and they can be investigated.
The attached document may be worth reviewing and worth a try although it states it applies up to MY 2009 (possibly excluding yours).
(Yes, the document is that short and is not missing any content.)
Fortunately, they do have a few ways to diagnose these issues with the factory Xentry Dianostics tool by querying the Battery Control Module. It will tell you the previous devices that caused the system to wake up and they can be investigated.
The attached document may be worth reviewing and worth a try although it states it applies up to MY 2009 (possibly excluding yours).
(Yes, the document is that short and is not missing any content.)
The following users liked this post:
Hatzenbach (10-02-2019)
The following users liked this post:
Hatzenbach (10-02-2019)
#4
Member
Thread Starter
My BMW i3 has a built in 3G connection and has a very hard time connecting when in my driveway
Would you know which fuse I need to pull to disable that?
#5
MBWorld Fanatic!
that actually makes a lot of sense. The problem started about the same time as 2G/3G cellular service in my neck of the woods degraded.
My BMW i3 has a built in 3G connection and has a very hard time connecting when in my driveway
Would you know which fuse I need to pull to disable that?
My BMW i3 has a built in 3G connection and has a very hard time connecting when in my driveway
Would you know which fuse I need to pull to disable that?
#6
Super Member
Even if you aren't a mBrace subscriber the "i" button will still connect to mBrace. When I did an update to mBrace (my 2007 had tel-aid), I subscribed to trial by pressing the "i" button.
#7
MBWorld Fanatic!
My W211 was completely deactivated, my W221 was not, and W210 DTA was deactivated. I am not completely sure what dictates the state they are in.
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#8
Member
Thread Starter
Keep in mind that these vehicles are rather complex even for today, and they have many control modules on several CAN networks, and one device can request a wake up signal on the CAN network and cause several devices to power up.
Fortunately, they do have a few ways to diagnose these issues with the factory Xentry Dianostics tool by querying the Battery Control Module. It will tell you the previous devices that caused the system to wake up and they can be investigated.
Fortunately, they do have a few ways to diagnose these issues with the factory Xentry Dianostics tool by querying the Battery Control Module. It will tell you the previous devices that caused the system to wake up and they can be investigated.
#9
MBWorld Fanatic!
I have found that workshops in my area service European vehicles, and European vehicles = VAG Group, BMW, Porsche, etc, with Mercedes being limited to standard service such as brakes, fluid changes, etc. Then, we have Mercedes independent workshops and as you can guess, all they do is Mercedes, and no BMW, VAG, will be seen in their shop.
I can’t explain why this is, but it is just an observation of workshops in my area.
#10
Super Member
Some do not have an active subscription (like yours) and some transceivers are in a deactivated state. These will not illuminate the SOS button on engine start (indicating self test mode) and require the “three button press” for about five seconds (SOS, wrench, and “I” simultaneously) to power up the transceiver and attempt over the air programming.
My W211 was completely deactivated, my W221 was not, and W210 DTA was deactivated. I am not completely sure what dictates the state they are in.
My W211 was completely deactivated, my W221 was not, and W210 DTA was deactivated. I am not completely sure what dictates the state they are in.
#11
MBWorld Fanatic!
You are misunderstanding what I'm saying. Without a subscription the call goes through, it happened when I did the conversion from tel-aid (I had no subscription) to mBrace(I had no subscription when I pressed the "i" button). I currently don't have a active subscription but can press the ""i" button and talk to an mBrace representative, I believe they will also dispatch a two truck of course I would have to pick up the cost unless I got towed to a dealer..
In DAS, you can deactivate TeleAid/mbrace, as you likely know, and it prompts to print a document for the customer to sign acknowledging their request to deactivate it. I believe some customers may opt for this that are more privacy-conscience and do not want where they travel to be triangulated by the cell towers and recorded, although it is not an active ESN. It should prevent the transceiver from powering up other than passing data on the MOST ring. If you are not a subscriber, supposedly you can use the SOS button for 911 calls, but if the transceiver does not have an MDN assigned to it, I can’t see how this is possible.
Last edited by Polar Bear; 10-02-2019 at 10:17 PM. Reason: Fixing autocorrect issues and correcting sentences making them understandable.
#12
Member
Thread Starter
Some do not have an active subscription (like yours) and some transceivers are in a deactivated state. These will not illuminate the SOS button on engine start (indicating self test mode) and require the “three button press” for about five seconds (SOS, wrench, and “I” simultaneously) to power up the transceiver and attempt over the air programming.
My W211 was completely deactivated, my W221 was not, and W210 DTA was deactivated. I am not completely sure what dictates the state they are in.
My W211 was completely deactivated, my W221 was not, and W210 DTA was deactivated. I am not completely sure what dictates the state they are in.
#13
MBWorld Fanatic!
#14
Member
Thread Starter
Pulled the fuses for the TeleAid (and now get warning on the dash, that TeleAid is not working, so I guess I pulled right ones).
Unfortunately that wasn't the issue.
Same battery draw as before, what is interesting is that it follows a pattern:
No activity between ~ 7 PM and 7 AM, lot of activity until Noon and then some on and off. Seems to be the same every day (when I compared with older recordings)
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Hatzenbach (10-08-2019)
#17
Senior Member