Sprinter electric battery alarm issue

That sounds familiar. I had a similar electrical issue with my old BMW. My battery alarm was also going crazy. Is the main battery okay? Have you checked that first? Sometimes a weak main battery can cause electrical issues.

The main battery seems fine; it starts with no problem. I think it's the auxiliary battery system. Where was the auxiliary battery in your BMW, and how did you fix it? Did it also show a battery alarm error?

If the main battery is solid, then the auxiliary battery is the suspect. On my BMW, the auxiliary battery was under the trunk floor, a pain to reach. After trying to fix it, I took it to a shop. The error codes were vague, and I didn't want to risk making things worse. Taking it to a workshop is the best course of action.

I took it to a workshop this morning, and they confirmed it's the auxiliary battery. They quoted me 330€ for the replacement and labor. It's expensive, but at least it will be resolved. Thanks for the help!