BMW 8 Series: Dead Battery Causing Multiple Failures?

Had the same issue with my 2016 BMW 5 Series diesel last winter. Started with similar symptoms, dim lights, sluggish start, and dashboard lit up like a Christmas tree with warning messages. Took it to the garage and turns out it wasn't just a simple dead battery. The alternator wasn't charging properly, which drained the battery completely. The battery was toast, completely sulfated and wouldn't hold a charge anymore. They had to replace both the alternator and the battery. Also found corroded battery terminals which made the situation worse. The whole thing was pretty serious since it affected multiple electrical systems. Would've caused more damage if left unchecked. Best to get it checked ASAP, when the battery's that weak, it can mess with everything from your engine management to safety systems. Hope this helps. Don't wait too long on this one.

Thanks for sharing your experience! Actually, that's really helpful since I'm seeing pretty much the exact same symptoms. Pretty scary how these electrical issues can affect so many systems at once. Just curious, do you remember roughly how much you ended up paying for the whole fix? Also, has everything been running smoothly since the repair, or have you noticed any other electrical quirks?

Hey there! Thanks for following up. After seeing my mechanic for those electrical issues I mentioned earlier, I'm happy to report everything's running perfectly now. The main culprit was indeed a heavily discharged battery that ended up being defective, they fixed that undervoltage problem completely. The whole thing set me back 290 € but honestly, it was worth every penny. Since the repair, my 5 Series has been running like clockwork, no more dim lights, no warning messages, and starts up perfectly every time. It's such a relief not seeing those system failure notifications anymore! The battery they installed is working great, and I haven't noticed any electrical quirks whatsoever. Looking back, I'm really glad I didn't wait any longer to get it fixed. These electrical issues can really snowball if you let them go too long. Definitely beats having to deal with more expensive repairs down the line! Let me know how yours turns out, hopefully it's a similar straightforward fix!

Thanks for all the advice everyone! Just wanted to update you all on what happened with my BMW. Finally took it to a mechanic yesterday, and turns out you were spot on. The battery was completely shot, and the alternator wasn't helping either. Got both replaced, plus they cleaned up some nasty corrosion on the terminals. Bill came to about 350 for parts and labor, which honestly wasn't as bad as I feared. Took her for a drive this morning and what a difference! No more flickering lights, starts up instantly, and all those scary warning messages are gone. Even the radio's working better, which I hadn't even realized was affected. Such a relief to have it sorted. Should've done it sooner instead of worrying about my last bad mechanic experience. Sometimes you just gotta bite the bullet and get things fixed before they get worse. Thanks again for pushing me to get it checked out, you probably saved me from bigger problems down the road!