BMW i8 Battery Nightmare: Multiple Systems Failing

As a BMW i3 2018 owner, I faced nearly identical symptoms last month. My dash was showing multiple warnings, particularly the overvoltage alerts, and the car struggled during start-up. The diagnosis at the garage revealed a failing voltage converter and a degraded high-voltage battery system. The repair involved replacing the voltage converter and recalibrating the battery management system. It was quite a serious issue that required specialized hybrid system knowledge. The voltage converter was causing irregular power distribution, which explained both the warning lights and the startup problems. What you're describing sounds very similar. With hybrid systems, these electrical issues typically point to either the converter or the battery management system rather than just a weak battery. My advice would be to get it checked specifically by a hybrid-certified technician. These symptoms shouldn't be ignored as they can potentially affect other electrical components if left unaddressed. The i8's system is more complex than my i3's, but the basic hybrid electrical architecture is similar. Consider getting a diagnostic from a certified dealership to be safe.

Thanks for sharing your experience! That sounds exactly like what I'm going through. It's really helpful to know I'm not alone with these issues. The voltage converter replacement seems to make perfect sense given the symptoms. I'm curious, do you remember roughly how much you ended up paying for the full repair? Also, has everything been running smoothly since the fix, or have you noticed any other quirks? Really appreciate your detailed response, especially about the hybrid-certified technician part. Think I'll definitely take that route rather than risking it with a regular mechanic.

Hey there! Happy to give you an update. I went ahead and took my i3 to a certified technician as discussed, and I'm glad to report the overvoltage issue is completely sorted now. The final bill came to 290 € to fix what turned out to be a heavily discharged battery that was on its last legs. I've put about 2,000 km on the car since the repair, and it's running like a dream, no more warning lights, no more start-up issues, nothing! The dash is finally back to being boring (in the best possible way). Honestly, it feels like I'm driving a different car now. I'm really glad I took the certified technician route. These hybrid systems are pretty complex, and having someone who really knows what they're doing makes all the difference. If you're still having those issues with your i8, definitely go for the specialist option. It might cost a bit more upfront, but it's worth it to get it done right the first time. Let me know how it goes if you get yours checked out. Always interested to hear how other BMW hybrid owners are getting on with their repairs!

Just wanted to update everyone on my i8 situation. Took your advice and went to a certified hybrid specialist. am I glad I did! My voltage converter was shot, just like you mentioned could be the case. The repair was pricier than I expected, around 900€ due to some additional work needed on the battery management system. But honestly, worth every penny. The car's running better than it has in months. No more light show on my dash, and the start-up is smooth as silk. The technician walked me through everything they were doing, which was a refreshing change from my last mechanic. They even showed me a few warning signs to watch out for in the future. Thanks again for pushing me toward a certified specialist. Sometimes you really do get what you pay for, and with these complex hybrids, it's definitely not worth cutting corners. Appreciate all the help and guidance!