B Klasse Hybrid Additional Battery Alarm Issue

I have a B Klasse as well, and I recall facing a similar battery signal situation some time ago. Though I didn't get an alarm system error, I did experience some weird electrical gremlins. Have you had the main battery checked recently? A weak main battery can sometimes cause the auxiliary battery to drain faster, triggering that alarm system issue you're seeing. Or it could just be the aux battery. How old is it?

Thank you for the quick response! I appreciate the information. I have not had the main battery checked recently, but that is a very insightful point. I'll definitely schedule a battery check for the main battery. As for the additional battery, I am not sure about its age, as it came with the car. Do you recall if the replacement was straightforward, or did it require any special tools or coding?

Okay, so about the battery alarm, yes, I did end up replacing my auxiliary battery. Honestly, if you're getting that error and the alarm isn't working, it's likely the culprit. Replacing it wasn't too difficult, but it's located in a somewhat awkward spot. I'd still recommend taking it to a workshop. They can properly diagnose it and ensure the new battery is correctly installed and registered with the car's computer. That 330€ estimate sounds about right for a replacement and coding.

I appreciate the confirmation and the advice. I suspected as much, but it's always reassuring to hear from someone who has experienced a similar issue. I will take your advice and schedule an appointment with a workshop to have the additional battery replaced. Thank you again for your assistance!