BMW i8 Won't Start: Battery Issues or Something Worse?

Hey there, i8 owner! I actually had similar symptoms with my 2019 BMW i3s Hybrid last month. From my experience, your symptoms strongly point to a failing voltage converter, it's the part that manages power distribution between the hybrid system and the conventional 12V system. When mine failed, it started exactly like yours, dimming lights, rough starts, and error codes. Took it to the dealership since this is a complex hybrid-specific issue. The voltage converter failure had actually caused some damage to the 12V battery too, so both needed replacement. It's definitely a serious repair that requires specialized diagnostic equipment and expertise. Not something you'd want to trust to a regular mechanic who isn't familiar with BMW hybrid systems. Would strongly recommend going to a certified BMW service center for this one. The voltage converter issue can cause more expensive damage if left unchecked. Hope this helps with your decision!

Thanks so much for sharing your experience! That sounds exactly like what I'm dealing with right now. You're right about needing specialized service, I'll definitely look into a certified center. Just curious, do you remember roughly how much you ended up paying for the whole repair? Also, has everything been running smoothly since the fix? Would be great to know what to expect. Thanks again for the helpful advice!

Hey again! Great to hear back from you! Since you asked, after getting my i3s fixed, it's been running absolutely perfectly. The starting issue completely disappeared after they sorted out that voltage converter problem. Here's the really good news, I actually didn't have to pay anything for the repair! Turned out the voltage converter failure was a consequential damage from a previous technical issue, so BMW covered it under warranty. Pretty lucky there! But even if it hadn't been covered, I'd say it was worth getting it properly diagnosed and fixed by the certified techs. My car feels like new again, starts up instantly, no more flickering lights, and all systems are working as they should. It's such a relief not having to worry every time I need to start the car. Just make sure to mention all the symptoms to the service center when you take it in, the flickering lights, starting issues, error codes, everything. It'll help them diagnose it faster. Let me know how it goes with your i8!

Just wanted to update everyone on what happened with my i8! Finally got it sorted out. Took it to a certified BMW service center based on your advice. You were spot on, it was the voltage converter causing all the trouble. The mechanic also found that my 12V battery was pretty much done for. The bad news? I wasn't as lucky with the warranty situation, had to pay out of pocket since mine had expired. The total bill was pretty steep, but honestly, it was worth every penny. The car's running like a dream now, no more anxiety about whether it'll start or not! The service was super professional too. The tech walked me through everything they found and fixed. Much better experience than my last mechanic. Thanks again for pushing me to go to a certified center, you saved me from probably making things worse with a regular shop. Time to enjoy my i8 properly again! Thanks everyone for the help!