BMW 5 Hybrid Dash Chaos: Auxiliary Battery Warning Signs

Hey there! I had nearly identical issues with my 2020 BMW 3 Series Hybrid last month. The symptoms matched yours perfectly, warning lights everywhere, start-stop acting up, and sluggish starts. Initially thought it was just the auxiliary battery, but turned out the main battery management system needed recalibration, and the auxiliary battery had completely failed. The repair involved replacing the auxiliary battery and reprogramming the battery management system. It was quite serious since the faulty auxiliary battery had been straining the main hybrid system. Glad I caught it when I did, as it could have potentially damaged other electrical components. The garage had my car for two days, they had to run multiple diagnostics to ensure no other systems were affected. From my experience, I'd strongly suggest going to a certified BMW workshop for this, as they have the specific diagnostic tools needed for hybrid systems. Best of luck with the repair.

Hey, thanks for sharing your experience! I'm dealing with something similar right now. Would you mind telling me how much you ended up paying for the whole repair job? Also curious if you've had any other electrical problems since getting it fixed? My mechanic's quoting me quite a bit and I'm trying to figure out if that's normal.

Hey again! Good to hear from you! Just to update you, after getting it fixed at the BMW workshop, I've had absolutely zero issues. The total cost came to 290 € for replacing the auxiliary battery and reprogramming the battery management system. That might seem a bit steep, but considering the specialized work and diagnostic tools needed for hybrid systems, I'd say it was worth every penny. I haven't had a single electrical problem since the repair, no more warning lights, start-stop works perfectly, and the car starts up strong every time. It's running like new again. Honestly, I'm just relieved I got it sorted before it could cause any damage to other components. If your mechanic is quoting significantly more, it might be worth getting a second opinion from a certified BMW dealer. They might be pricier initially, but they really know their stuff when it comes to these complex hybrid systems. Let me know how it goes with your repair!

Thanks so much for all the detailed info! Just got back from the mechanic today actually. You were right about going to a certified dealer, I bit the bullet and took it there. Turns out my issue was pretty much identical to yours. The whole ordeal wasn't as painful as I expected. They replaced the auxiliary battery and did the system recalibration. Bill came to about 320 €, which was actually less than what my regular mechanic quoted. They had it done in a day and a half. The best part? The car's running like a dream now. No more Christmas tree dashboard, start-stop is working perfectly, and those weak starts are history. Really glad I asked here first, saved me from potentially making an expensive mistake with an unqualified mechanic. Thanks again for helping me dodge that bullet! Hopefully this thread helps other BMW hybrid owners facing similar issues.