Mini One Undervoltage Warning

The symptoms you describe certainly point to a significant electrical problem. Has the battery's condition been professionally assessed? A discharged or defective battery is a common cause, especially with the observed starting issues and system failures. However, it's important to also consider the charging system. Is the alternator functioning correctly and providing the necessary voltage to charge the battery while the engine is running? A faulty voltage regulator can also lead to undervoltage issues. Have you checked for any parasitic draws that might be draining the battery when the car is off?

Thank you for your quick and insightful reply! You mentioned the alternator and voltage regulator. Is there a way to test these components to determine if they are functioning correctly? I'm not very experienced with electrical diagnostics, but I am willing to learn. Could you perhaps elaborate on how a faulty voltage regulator might cause these undervoltage problems? I am very curious!

Considering the symptoms and the age of the vehicle, it is highly probable that the battery is the primary culprit. A defective battery can indeed cause a cascade of electrical issues, including the undervoltage warning and system malfunctions you are observing. While it is possible that the alternator or voltage regulator is contributing to the problem, it is more likely that they are simply unable to compensate for the failing battery. Given your lack of experience with electrical diagnostics, I would strongly recommend taking the car to a qualified workshop for a proper diagnosis and battery replacement.

I wanted to provide an update regarding the undervoltage issue with my Mini One. Following your advice, I took the vehicle to a reputable workshop. As you suspected, the battery was indeed defective. After replacing it, the electrical problems have disappeared, and the car is starting perfectly again. The total cost, including the battery and labor, came to 290€. Thank you so much for your accurate diagnosis and guidance. Your expertise saved me a lot of time and potential misdiagnosis!