Mini Countryman alarm issues

Interesting issue. Sounds remarkably similar to a problem I encountered with my Mini Countryman a while back. The 'battery signal' and malfunctioning car alarm pointed directly to a failing auxiliary battery. These systems are often interconnected; the car alarm relies on that little battery when the main one's under stress or disconnected. Have you had the battery properly tested? A simple voltage check might not reveal the problem if a cell is failing under load.

Auxiliary battery, huh? I was so focused on the main battery, I didn't even consider that. Where exactly is this auxiliary battery located? And is there any way to test it myself, or am I better off just taking it to a shop?

Yes, in my case with my Mini Countryman, the auxiliary battery was tucked away near the main battery, but its location can vary significantly between makes and models. Given your description, it's likely the auxiliary battery is indeed the culprit. While there are ways to test it yourself with a multimeter and load tester, accessing it and interpreting the results correctly can be tricky. For the sake of accuracy and avoiding potential electrical mishaps, I'd strongly advise taking it to a qualified workshop. They can pinpoint the issue definitively and replace the battery if necessary. Sounds like that defective auxiliary battery would cause issues to the car alarm.

Big thanks for the insights! Dropped it off at the workshop, and yep, auxiliary battery was shot. €330 later, the alarm's back in action, and that annoying battery signal is finally gone. Appreciate the help!