BMW 5 Hybrid Won't Start: Battery vs Bad Mechanic?

Hey there! I can relate to your situation. I have a 2020 BMW 3 Series Hybrid and experienced similar symptoms last month. The root cause in my case was a faulty voltage regulator that damaged the alternator. The initial mechanic missed diagnosing the voltage regulator, which led to premature alternator failure. Had to get both components replaced as the alternator was damaged beyond repair. It was quite a serious issue since it could have left me stranded anywhere. The hybrid battery system wasn't affected, thankfully, but the regular 12V system was completely unreliable. Your symptoms sound very similar, the dim lights and starting issues point to electrical system problems. I'd suggest getting a proper diagnostic scan done by a certified BMW technician who's familiar with hybrid systems. These electrical issues can snowball if not addressed correctly the first time. Based on my experience, don't take chances with non-specialist mechanics for hybrid BMWs. The dual power systems make them more complex than conventional cars. Best of luck.

Thanks for sharing your experience. That's really helpful information, sounds exactly like what I'm experiencing with my car. I've been worried about going to another mechanic, but you're right about needing someone who knows hybrids. Can I ask how much the voltage regulator and alternator replacement set you back? Also, have you had any other electrical issues pop up since getting it fixed?

Hey again! Good to hear back from you. Actually, I had really good news after taking it to a BMW specialist. The engine starting issue was completely resolved, turns out it was just a consequential error from the voltage regulator problem. The mechanic cleared it at no cost to me since it was directly related to the previous repair. Since getting the voltage regulator and alternator replaced (which cost me around 1,200 for parts and labor), the car's been running like a dream. No more flickering lights, no starting issues, nothing. It's been about a month now, and everything's working perfectly, the electrical system is stable and the hybrid system is functioning just as it should. One piece of advice though, if you do get it fixed, make sure they check all the connected systems afterward. These electrical issues can sometimes cause chain reactions, but a good specialist will catch all of that. Really glad I could help! Let me know how it goes with your car.

Thanks so much for all the detailed info! I actually just got back from a certified BMW specialist today. You won't believe it, it was exactly what you described! My voltage regulator was shot, and they found the alternator was starting to fail too. Got both replaced and a full system check. Bill came to about 1,300, which wasn't fun, but at least it's fixed properly now. The mechanic was super professional and explained everything clearly, unlike my previous experience. They even showed me the worn-out parts and why they needed replacing. Car's running perfectly now, starts right up, no more dim lights, and all error codes are cleared. Really grateful for your advice about going to a specialist. You saved me from probably making another expensive mistake with a regular mechanic who might've missed the real issue. Thanks again for sharing your experience, it really helped me make the right decision this time!