Ok, battery drained from full charge after two hours of parking. Time for a new battery. Just curious, this happened suddenly. My experience of old battery has been a gradual deterioration of charge. ☹️. Before this saga all has been well. My drives are very short and I hardly hit the freeway🤔.

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'05 E53 X5 4.4i, '97 E39 528, '07 E92 335i, '16 F86 X6M.