Battery drain 211

[MAK]

W211 .E200 .Compressor .estate model 2008 .

Car has a battery drain of 2 amps that I have not been able to isolate , removed all the fuses one by one to isolate the fault,no success.
Likely missed something and appriciate guidance.
This model does not have a aux battery under the ac filter area.
Mak

 

[mersum1es]

2 amps could be breather heater if car has one. More like it sound some CAN is awake... did you wait long enough between putting fuses back? That's annoyingly slow process when you need to wait 5-10 mins between fuses waiting car go to sleep.

Voltage regulator has been proposed many times for culprit but I cant remember any confirmed case in these 'newer' type cars (It was well possible over 20 year ago)

 

[Oldspanners]

W211 .E200 .Compressor .estate model 2008 .

Car has a battery drain of 2 amps that I have not been able to isolate , removed all the fuses one by one to isolate the fault,no success.
Likely missed something and appriciate guidance.
This model does not have a aux battery under the ac filter area.
Mak

Have a look at this it works and the tables are very useful and saves having to pull fuses and waken up systems.

 

[MAK]

2 amps could be breather heater if car has one. More like it sound some CAN is awake... did you wait long enough between putting fuses back? That's annoyingly slow process when you need to wait 5-10 mins between fuses waiting car go to sleep.

Voltage regulator has been proposed many times for culprit but I cant remember any confirmed case in these 'newer' type cars (It was well possible over 20 year ago)

I had checked alternator for diode leakage, removed connector for a rectifier leakage ,both ok.
Charging is normal as well.

 

[MAK]

Have a look at this it works and the tables are very useful and saves having to pull fuses and waken up systems.

Innovative way to test ,I will give it a try as well.
Incidently ,with the battery terminals removed alarm activated , the sound is not very strong ,where would the power supply be for the alarm as this model does not have a auxiliary battery under the bonnet area.

 

[Blobcat]

Innovative way to test ,I will give it a try as well.
Incidently ,with the battery terminals removed alarm activated , the sound is not very strong ,where would the power supply be for the alarm as this model does not have a auxiliary battery under the bonnet area.

Alarm sounder has its own internal battery

 

[sonic]

Alarm sounder has its own internal battery

I seem to remember someone had a drain on the sounder battery?

 

[Blobcat]

I seem to remember someone had a drain on the sounder battery?

Get some water in the sounder and quite likely

 

[Roxie]

This sort of drain could be the phone control unit under the boot floor. I seem to remember the fuses are also under there somewhere.

 

[MAK]

This sort of drain could be the phone control unit under the boot floor. I seem to remember the fuses are also under there somewhere.

Thanks . Will check the phone supply next .
The boot area also carries the main fuse box.

 

[Roxie]

Thanks . Will check the phone supply next .
The boot area also carries the main fuse box.

The rear sam is indeed in the boot but I think there is a smaller fuse box under the carpet and under the plastic tray.

 

[MAK]

Earlier on i had noticed that with Battery disconnected, I got a small voltage reading of approx. 2v at the front jumper post+ and -- post , this slowly draws down to a low value ,hovering around a residual 0.5 V. Perhaps a small battery under the dash area?

 

[mersum1es]

No 2nd battery facelift W211.

 

[Roxie]

Earlier on i had noticed that with Battery disconnected, I got a small voltage reading of approx. 2v at the front jumper post+ and -- post , this slowly draws down to a low value ,hovering around a residual 0.5 V. Perhaps a small battery under the dash area?

Or residual current in the phone control unit?

 

[MJJ]

Mak,

I have recently found, and fixed a current drain on my facelift S211. Nowhere near 2A though, and in my case, it was the alarm backup siren keeping the overhead control panel awake.

Martin.


Sent from my iPhone using Tapatalk

 

[Blobcat]

Mak,

I have recently found, and fixed a current drain on my facelift S211. Nowhere near 2A though, and in my case, it was the alarm backup siren keeping the overhead control panel awake.

Martin.


Sent from my iPhone using Tapatalk

Please cut and paste your guide

 

[MAK]

Mak,

I have recently found, and fixed a current drain on my facelift S211. Nowhere near 2A though, and in my case, it was the alarm backup siren keeping the overhead control panel awake.

Martin.


Sent from my iPhone using Tapatalk

 

[MJJ]

Hopefully this copy/paste works.

Martin.

Afternoon all,

I have recently chased, and solved a current drain on my 2009 S211 E220. As it was a right pain to find, I thought it may help to document it - might be useful for others.

I only noticed the drain problem as we entered lockdown, and the car stopped being used very often. After 4 or 5 days, the battery had reached 10V and the car would not start. The usual method of diagnosis - multimeter inserted in series with the battery +ve wire, and I traced the drain of around 160mA to fuse 9 in the boot. This is the overhead control panel (i.e. interior light panel, front).

The useful WIS section on "quiescent current" tells me that a drain of that magnitude is likely a CAN module staying awake - i.e. the OCP module was not sleeping after the car was locked. The attached image from WIS shows what the current profile should look like as the car goes to sleep, post locking. Mine now only uses 35-40mA after 6 or so minutes.

After much diagnosis and a helpful post on a US forum, it transpired that a tired alarm siren (behind the front wing wheelarch liner, OSF on facelift, NSF on pre-facelift) was stopping the OCP module sleeping. My best guess is that the internal battery in the alarm siren fails over time, and thus always demands a charge from the car - this somehow keeps the OCP awake, probably because the "interior sensor disable" button is in the OCP.

Anyway, alarm siren removed, current drain gone. No adverse effects so far, though if anyone tries to steal the car by cutting the main battery lead, then there will be no siren sounding. I can live with that. A new alarm siren appears to be around £120, but I don't see the need to replace it, personally.

Martin.




Sent from my iPhone using Tapatalk

 

[MAK]

Martin .
interesting ! what was the sequence of fault rectification?

 

[MJJ]

Martin .
interesting ! what was the sequence of fault rectification?

Hi,

Sorry, not sure I understand the question.

Martin.


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