So this came up in a conversation with a colleague yesterday and now I can't stop thinking about it because I genuinely don't know the answer. He was telling me his F30 threw a bunch of weird errors after he had the battery swapped at a random workshop, things like the charging system warning and some comfort features acting up, and the dealer later told him it was because the new battery was never registered to the car's management system. I had no idea BMWs even needed that, I always thought a battery was just a battery, you pull one out and put another in. Apparently on newer models the ECU actually monitors the battery's history and if you drop in a replacement without telling the system, it keeps charging it as if it's the old worn out unit which then either overcharges or undercharges the new one. He ended up going through a proper BMW battery replacement service that handled the coding side of things alongside the physical swap and said everything went back to normal immediately. Now I'm wondering whether the shop I used for my 3 Series two years ago actually did that or just fitted the part and called it a day, because I did notice the stop start system was a bit inconsistent for a while after but just assumed it was a temperature thing. Does anyone with more BMW knowledge know how to check after the fact whether the battery was properly registered or not?