C230 Sport Coupe battery trouble
 

I enjoy driving C Coupe. It's a handy sports car in the city. However, the battery of my car have died three times within 8 months (brand new).

According to the dealer, my car consumed more AMP (battery) when the door is unlocked! (after turn-off the key & wait 30minutes till all the stand-by device is shut down). When door was locked, minor usase of battery was detected. Is this the way is should be? Or something is wrong specifically with my car?

My car is parked at the attended parking where nobody lock the door (I have to ask the attendant to remove the key from the ignition slot). So, it is difficult to keep the door locked in the garage.

Please advise if my car is normal (or not), and what to do?

Thank you.

Sato:(

You seem to have a problem, if door is unlocked or locked this shouldn't effect battery life. Many people with home garages keep their Mercedes unlocked, with no problem

Mercedes does say that a problem with running down the battery can arise if the key is left in the ignition when the car is not in use.

I would have to agree with Ethan, my wifes C230 sits in our garage unlocked with the keys in it every night, and we have never had any battery problems. Her car is a 2000 C230 with the original battery.

I think I would ask the dealer for a better explanation than the one they gave you and to "FIX", what sounds like, a very real problem.

Dale

Hi Sato, something is definitely wrong with your car! When checking the rest current draw, MB specifies checking it with the doors unlocked as well as locked. On vehicles with the COMAND system they require the NAV disc be removed as well. As far as waiting thirty minutes for all the ECU's to shut down, that may be a little mis-leading. I've done current draw tests that have lasted from less than ten minutes to well over an hour! I'll bet one of the ECU's on your cars interior data bus isn't shutting down properly. This causes the cars' electrical system to remain partially turned on, draining the battery. From the sound of your complaint(three times in 8 months) it's not a problem that always exists. Your dealer should connect an ammeter to measure the rest current draw and monitor it periodically for as long as it takes to determine the cause of your problem. I've had to monitor cars for several days before the malfunction occurred. Dead batteries caused by excessive rest current are one of the most difficult diagnosis' to make, even for a highly skilled MB tech. MB vehicles with networked ECU's make it especially challenging. Commitment to customer satisfaction and diligence are important ingredients to your dealer seeing this problem through. Good luck and let me know how it goes.

Tell them to check the switches in your cars door jam.
I have seen these go bad or even get pushed through and caus the CAN data bus to stay active.
Just a thought.
Brian