S320, 2018, 32,000 kilometres
I would greatly appreciate any assistance or advice, as I am at my wit's end.
In recent months, I have encountered recurrent battery depletion when the automobile is not operated for a few days. Completely unresponsive, and on one occasion, it entirely reset the SRS system, resulting in a persistent error message necessitating a reset.
I am driving significantly less than I previously did for different reasons; at times, I may not drive for several days and then only for approximately 30 minutes.
During the last servicing three months ago, I had the battery replaced, since the technician indicated it was the 'large battery' and the cost was £250, which I accepted.
Within a week, the issue reemerged, with the vehicle struggling to start—repeatedly cranking, electrical systems malfunctioning, and ultimately 'catching' at the last moment. It operates adequately until the subsequent occasion.
Consulted a reputable auto electrician regarding the vehicle; his recommendation was to 'increase its usage.'
I left the car unused for seven days lately; it started successfully the first time but failed to start the following morning.
I have acquired a Ring Ultraboost 1500 Jump Starter, which functions exceptionally well and has successfully started the car four times when required.
The battery was depleted after being left for 24 hours with a Mercedes-Benz dealer for air conditioning maintenance.
I remained in the vehicle for 50 minutes utilising the Comand system with the engine off, received a warning to activate the engine, and, naturally, it failed to start.
I receive notifications from the Mercedes Me app indicating that "the charge level of your vehicle's starter battery is critical" and "12V battery is very low."
Therefore...
1. Is there an additional battery that requires replacement? My internet enquiries have yielded inconclusive results.
2. Can anyone provide any insights? I am quite exasperated; I cherish my automobile yet am losing confidence in it, which is somewhat frustrating.
Any ideas or suggestions would be much appreciated.