JustCarsForum - Your Ultimate Automotive Community

2018 S320 with 32,000 miles

I would much appreciate any assistance or advice. I am feeling quite frustrated and desperate.

Over the last several months, I have had a recurring issue of the car's battery going flat when it is not driven for a couple of days. The battery was entirely discharged, to the point where the engine wouldn't even start. Additionally, there was one instance when the battery caused the SRS system to malfunction, resulting in a persistent error message that needed to be reset.

Due to different reasons, I have significantly reduced the amount of time I spend driving. There are occasions when I don't drive for a couple of days, and when I do, it is usually for a duration of about 30 minutes.

During the most recent service, which took place 3 months ago, I had the battery changed. The service provider informed me that it was the 'large battery' and the cost was £250, which I found acceptable.

Within a week, the issue recurred, as the vehicle struggled to start, with the electrical system malfunctioning and only managing to start at the last moment. Afterwards, it operates well until the subsequent occurrence.

Entrusted the vehicle to a highly recognised auto electrician, who advised me to increase my driving frequency.

After leaving the automobile unused for 7 consecutive days, it successfully began on the first attempt but failed to start the next morning.

I have made a financial investment in a Ring Ultraboost 1500 Jump starter, which has shown exceptional performance by successfully starting my vehicle on four separate occasions when it was necessary.

The battery was completely depleted after being left with an MB dealer for 24 hours after repair of the air conditioning system.

I remained inside the vehicle for a duration of 50 minutes, using the Comand system while the engine was not in operation. Subsequently, I received a cautionary message to activate the engine, and unsurprisingly, it failed to start.

I get notifications from the Mercedes Me application indicating that the charge level of my vehicle's primary battery is at a critical level and that the 12-volt battery is extremely low.

Therefore...

1. Is there an additional battery that requires replacement? I have conducted online searches, but they have not provided me with clear results.

2. Can anybody provide any insights or opinions? I am very frustrated and exasperated - I have a strong affection for my automobile but my confidence in it is diminishing, which is rather irritating.


I would much appreciate any advise or ideas.

After the automobile is turned off, some systems continue to operate for a period of time. Typically, systems enter a sleep mode, but sometimes they fail to do so and result in an unintended current drain.

Did your reputable auto electrician verify the presence of current draw while the automobile was turned off?

Perhaps the device was first equipped with a Tracker, which has a compact rechargeable battery that is replenished by the vehicle's battery. This compact battery may be defective, as it has occurred to an acquaintance of mine. It took four months before someone made a diagnosis.

Thank you to both of you. I am uncertain if any drainage was sought or found, I'm sorry.

I am unable to visit MB dealerships due to their very untrustworthy nature. I find it impossible to accept whatever they say, since they have a history of providing false information.

Is there a second battery available?

I am uncertain about the presence of a second battery, unless the vehicle in question is a hybrid. However, it is essential to have an automotive electrician or an independent Mercedes-Benz specialist inspect for any parasitic drain and attempt to identify the specific module or circuit that may be responsible for the issue.

If you provide us with the name of the specific town or city in which you reside or are in close proximity to, our members will hopefully be able to provide recommendations for individuals or professionals.

Auxiliary battery will be present in your automobile. Flatness might lead to many complications.