BMW i3 Shuts Down: High-Voltage System Error Alert

I had a similar issue with my 2016 BMW i4 last month. The symptoms were nearly identical, unusual shutdowns and reduced power warnings. Turned out the high-voltage battery was heavily discharged and showing signs of deterioration. At the garage, they ran diagnostics which showed multiple cell modules were failing. They had to recondition the entire battery pack and replace two defective modules. The repair was quite serious since it involved working with the high-voltage system. I'd strongly suggest getting it checked at a certified EV specialist rather than a general mechanic. The battery management system needs proper diagnostic tools to accurately identify which cells are causing problems. In my case, waiting longer would've risked permanent damage to the whole battery pack. If your symptoms match what I experienced, you'll want this looked at soon. The unusual shutdowns are a safety concern, and the reduced power mode is the car's way of protecting the battery system from further damage.

Thanks for sharing your experience! That's really helpful because I'm seeing such similar issues with my i3. Good to know about the cell modules, that makes a lot of sense given my symptoms. Just curious, do you remember roughly how much you ended up paying for the whole repair? And has everything been running smoothly since they fixed it, or have you noticed any other quirks?

Hey there! Happy to give you an update. After getting it fixed, my i4 has been running like a dream, no more scary shutdowns or error messages popping up. The high-voltage system error that was giving me headaches completely disappeared after the repair. The total bill came to 290 € for fixing the heavily discharged battery issue. Money well spent if you ask me, especially considering how worrying those unusual shutdowns were. The car feels much more responsive now, and I'm back to enjoying the full power instead of limping along in reduced power mode. It's been about a month since the repair, and I haven't noticed any quirks or problems. The battery's holding charge perfectly, and the performance is back to what it should be. Really glad I didn't wait any longer to get it sorted out. If you're seeing the same symptoms, I'd definitely recommend getting it checked sooner rather than later. The peace of mind alone is worth it!

I took your advice and got my i3 checked out by an EV specialist. You were right, it definitely needed professional attention! The diagnostic showed similar battery cell issues to what you described. The repair cost a bit more than yours at around 350€, but totally worth it. The mechanic explained everything clearly and showed me the problematic cells. Was a much better experience than my last mechanic who just seemed confused by electric vehicles. The car's running perfectly now, no more sudden shutdowns or reduced power warnings. Such a relief not having to worry about getting stranded somewhere! Really appreciate you sharing your experience, it gave me the push I needed to get it sorted properly instead of trying to save money at a regular garage. Definitely learned my lesson about using EV specialists for these kinds of issues. Thanks again for all your help. It's great having these issues behind me and being able to enjoy driving my i3 again!