BMW i3 Battery Blues: Multiple System Failures Puzzle

Hey there! I had nearly identical issues with my 2017 BMW i8 Hybrid last winter. The symptoms match exactly what I experienced, slow starts, system warnings popping up out of nowhere, and those annoying flickering lights. Turned out my main battery pack had a failing cell that was causing the whole system to go haywire. The first signs started with the sluggish start and progressed to those undervoltage warnings. Initially thought it was just the 12V battery, but the diagnostic tests revealed it was more serious. Had to get the entire battery module replaced at a specialized hybrid service center. It wasn't a quick fix, took them about 4 days to complete all the necessary tests and repairs. They also had to recalibrate several systems afterward to get everything working properly again. My advice? Skip the regular mechanic and find someone who specifically works with hybrid systems. These cars need specialized knowledge, and a general mechanic might miss the underlying issue.

Thanks for sharing your experience! That really helps since the symptoms match up perfectly with what I'm dealing with. Sorry to hear you had to replace the entire battery module though, that sounds pretty serious. Do you remember roughly how much you ended up paying for everything? Also, has the car been running smoothly since the repair, or have you noticed any other quirks popping up? Still trying to figure out if I should brace myself for a big repair bill here.

Hey again! Just wanted to follow up, your questions brought me right back to my i8 situation. I've got good news though: after I finally found that specialized hybrid center I mentioned, the fix was actually much simpler (and cheaper!) than my original battery module replacement. Turns out it was just the battery being heavily discharged, causing those undervoltage issues you're seeing. Total bill came to 290 € which was such a relief compared to what I initially paid. And here's the best part, since getting it sorted, my car's been running like a dream! No more flickering lights, no unusual system warnings, and it starts up perfectly every time. I've put about 15,000 km on it since the repair with zero issues. Those undervoltage warnings haven't shown up again either. Really night and day difference from before. Honestly, sounds like you might be dealing with the same thing, so hopefully you won't need anything as major as my first repair. Just make sure you get someone who really knows their hybrid systems!

What a relief to hear about your experience! Finally got my car checked out at a new mechanic yesterday, and you won't believe what happened. The specialist I found was actually super thorough, pulled up every error code and ran a complete diagnostic. Found out it wasn't nearly as bad as I feared! Turned out to be a combination of a weak 12V battery and some corroded connections that were messing with the power distribution. The mechanic cleaned everything up, replaced the battery, and ran a full system check. Total bill came to around 400 bucks, way less than I was expecting after hearing about battery module replacements! Drove it home last night and it's like having a completely different car. No more flickering lights, starts up instantly, and all those annoying system warnings have disappeared. Should've switched mechanics months ago instead of worrying about it. Thanks again for pushing me to find a hybrid specialist, you saved me from probably spending way more at my old mechanic who clearly didn't know what they were doing with these cars!