C220 CDI Battery Drain

[EagleI]

I have a new battery fitted by MB. If I don't drive the car for 3-4 days, the battery is completely drained of power and requires a jump start. This has happened 4 times in last 6 months. MB / AA checked the battery and alternator etc and all is well. No problem is detected when the car is used everyday.

I have just had a full electronic diagnostic check done over 2 days and the finding is that the battery is using 7amps (should be 3amp max) of power after the engine has been switched off completely, but no one is able to identify which component is causing this.

Has anyone experienced similar problem ? Any suggestions where the problem may lie ? I have Command system and there are no fault messages to provide any clue. MB with all their diagnostic capabilities and knowledge base can not help !!

Any help / suggestion - most welcome

 

[Ellsy Tanners]

Then Your dealer is a load of Toss, it must be able to be found, it a process of ilimation which cannot fail to find it, i dont understand how they have not being able to find it.

Common cause are seat control modules, door control modules, dodgy tracker systems or simmilar, even as simple a faulty outside temp sensor. try a different dealer or indie!!

 

[television]

Those figures are wrong, at 7 amps it would go flat in 9 hours, the boot light on will kill the battery in 3 days

as Ellsy Tanners find someone who knows what they are doing

 

[Steve Taxi]

Eagle, I have had the same problem with a similar car, last week I suspected that the A/C sensor fan in the front interior light was not switching off, I have disconnected it but not yet left the car for more than a day so not sure if its cured, hope this is some help.

 

[anyweb]

another fault finding option is to remove fuses one by one to rule out what is drawing the power. it's a matter of patience and testing. you'll get to the bottom of it eventually,

 

[television]

Its easiest with an ammeter costing under £10

 

[BlackC55]

I need an ammeter that will measure mili amps with a popable fuse.

 

[television]

I need an ammeter that will measure mili amps with a popable fuse.

CPC have a ammeter comes with 2 sets of lead, one set has fuse spades that plug directly into a fuse holder, and measures 20 amp the cost is under £10

I can get you one

 

[EagleI]

Hi Malcolm - It is possible that I mis-heard the amp values, but in about 3 days the battery is dead. Thankyou for the boot light clue - I will check this out.

Many Thanks for your response.

Raj

 

[EagleI]

Thank you Elssy Tanners - I agree with you - MB dealers are a hit and miss and want I can't afford to shell out £100+ per hour labour rate and they don't find the cause.

Another independent specialist has eleminated some of the things, but the problem by the sound of it can only be eleminated by process of elemination - a long and tedious process as the system takes 10+ minutes to shut down to see if the relevant fuse is a source. I will take up your suggestion and others with the amp meter.

I thank you for your advise - much appreciated.

Raj

 

[may2350]

I had a bad battery drain on a c270 1/2 amp it turned out to be a control box under drivers seat if you have one unplug the supply cable and see if the drain stops.

 

[EagleI]

Mobile Phone Control Unit

I took my C220 CDI to MB dealer for diagnostic of the battery drain, and they have identified the problem to Mobile Phone Control Unit. To replace this will cost nearly £800 (£350part + Labour). If I simply have the unit disconnected, then I will encounter other problems such as radio or command etc. as the unit goes thru the same Can unit.

Curiously, an independent diagnostic place had checked the phone, but did not find the problem - and the dealer has.

Any cost effective suggestions ?

 

[jberks]

firstly have it unplugged for a couple of weeks anway - just to confirm that this is the problem. Then, assuming it is and all is well without it, and there is a problem with command, (I don't see why it's abscence would cause a problem but if it does), they should be able to 'unregister' it via star. After all, what do they do with a car without a phone module?