W211 battery completely flat.

[mrcbenz]

Recently bought a W211 E Class 52 plate 270 CDI, not using it just yet and it's been locked in my father's garage for approximately 3 weeks. I tried opening the doors with the keyfob to check a few things under the bonnet and nothing happened. I used the blade key to open the door and boot, to ensure I could get in and to the boot. Should the alarm have come on? I put the keyfob in the ignition and nothing happened, couldn't turn the key to the first position to unlock the steering. I'm suspecting it's the battery completely flat and think it was on its way out anyway as I saw a 'consumer electronics off' message on the dash when I picked it up. Think I'll purchase new batteries for the car just to be safe as I'm not sure how old they are. Couldn't see if the boot battery is the AGM type.

I'll be charging the current battery or jump starting it next week to get it to my local independant garage. Once I charge the battery, am I right in assuming that the car will start and the steering will unlock or will the immobiliser prevent me from driving it? And I will be seeing lots of error messages on the dash once the battery is reconnected?

Any information will be much appreciated.

Many thanks in advance.

 

[Justin1600]

If you are going to jump start the car, please make sure that the car that you are jumping from is NOT running.
You will see the date your battery was made on the terminal, if it is more than 4 years old it is wise to replace it.
Don't forget the smaller one under the bonnet aswell.
Then get it's charge rate checked and also for battery drain.
Once you change the battery turn the steering lock to lock a couple of times, re-set the clock and the windows ( hold at the top on the first click of the switch for 4 seconds ) to set each window

 

[mrcbenz]

Thanks Justin1600 for that information.

Just rang my local MB dealer and they quoted £93.60 for the main battery and £108 for the auxilary. Not bad I think from a main dealer. The parts guy couldn't tell me if they are the AGM type but assured me they are the correct batteries for the car. The rear battery seems easy enough to relace, haven't looked at the auxilary battery connections yet. Is it pretty straight forward? As well as reseting the windows, clock and turning the wheel lock-to-lock, will I need dealer assistance to clear any fault codes with their Star Diagnostics?

 

[mr. shr]

Seems odd you're changing both batteries at the same time. Have you had any tests done? Does your local indy have a STAR machine?
If not, have you searched around your area for someone that does?

Think it would be better to have some diagnostics done before you change both batteries in one go.

 

[Diesel Benz]

Thanks Justin1600 for that information.

Just rang my local MB dealer and they quoted £93.60 for the main battery and £108 for the auxilary. Not bad I think from a main dealer. The parts guy couldn't tell me if they are the AGM type but assured me they are the correct batteries for the car. The rear battery seems easy enough to relace, haven't looked at the auxilary battery connections yet. Is it pretty straight forward? As well as reseting the windows, clock and turning the wheel lock-to-lock, will I need dealer assistance to clear any fault codes with their Star Diagnostics?

The AUX battery is easy, under the HVAC dust filter. Be careful with the rear one, ignition off long enough to make control units go to sleep to avoid current peaks. SAMs tend to be sensitive.

 

[mrcbenz]

Seems odd you're changing both batteries at the same time. Have you had any tests done? Does your local indy have a STAR machine?
If not, have you searched around your area for someone that does?

Think it would be better to have some diagnostics done before you change both batteries in one go.

Hi mr.shr, thanks for your reply. As I'm not sure how old both batteries are, thought perhaps best to change them. I know the E-Class can use a lot of battery power and don't want to be stranded. My independant has Snap-on tool rather than a STAR. I'll have the batteries tested.

 

[mrcbenz]

The AUX battery is easy, under the HVAC dust filter. Be careful with the rear one, ignition off long enough to make control units go to sleep to avoid current peaks. SAMs tend to be sensitive.

Thanks Diesel Benz, knew where the aux battery was ... hiding! Thanks for the additional tip too.