BMW XM Battery Nightmares: Multiple Systems Failing

Hey there! I had a similar issue with my 2020 BMW X6 M50i last month. The symptoms you're describing match exactly what I experienced, error messages popping up out of nowhere, electrical glitches, and cold start problems. Took it to the garage and turns out both batteries needed attention. The auxiliary battery was completely dead and had damaged the charging system. The main battery was also affected because the car's electrical system wasn't distributing power properly. It was actually quite serious, the technician mentioned that continuing to drive with these issues could've damaged other electrical components. The fix involved replacing both batteries and recalibrating the power management system. Took about a day and a half to complete all the work. Since then, everything's been working perfectly, no more error messages or start issues. Given it's a complex electrical system issue, I'd strongly suggest going to a specialist who really knows BMW electronics. These symptoms shouldn't be ignored as they can lead to bigger problems. Hope this helps!

Thanks for sharing your experience! That's really helpful as it sounds exactly like what I'm dealing with. Good to hear you got it sorted properly. Just curious, do you remember roughly how much the whole repair set you back? And has everything stayed working fine since the fix, or have you noticed any other quirks popping up?

Hey again! Glad my previous reply helped! Actually, I've got good news, my repair was much simpler than I initially expected. The main issue was just the auxiliary battery malfunction, which theyaged to fix completely. It set me back 290 €, way less than I was worried about after seeing all those error messages! Everything's been running perfectly smooth since the fix two months ago. No more error messages, the start-stop function works like a charm, and those annoying electrical glitches are completely gone. The cold starts are back to normal too, the car fires up instantly every time. Much better outcome than I initially thought when I saw all those warning lights! Really relieved it wasn't both batteries like they first suspected. My X6 M50i is running like new now, and I haven't noticed a single quirk since the repair. If you're still looking to get yours checked out, definitely get it done sooner rather than later. Those electrical issues can snowball if left too long. Feel free to ask if you need any other info!

Thanks so much for the follow-up! Just wanted to update you, I took your advice and got my XM checked out today. Turned out to be pretty similar to your situation. The mechanic I found was really knowledgeable about BMWs, and he spotted the issue right away. Had a faulty auxiliary battery that was causing all those weird electrical problems. The whole thing cost me about 350 €, a bit more than yours but still not as bad as I feared. They got it done in just a few hours, and I'm already noticing a huge difference. No more warning lights, and the start-stop is working perfectly again. Such a relief! Really appreciate you sharing your experience, it gave me the push I needed to get it sorted before it got worse. Definitely learned my lesson about not waiting too long when these electrical issues pop up. Thanks again for all your help!