Your M5 F90 shouldn’t go dead overnight. Here’s how to find a parasitic electrical draw, what parts to check first, and whether it’s safe to keep driving.
Why is your M5 F90 draining overnight?
If the battery is flat after the car sits overnight, a parasitic draw is the most likely suspect. The F90 has many control modules, and one module that stays awake can pull 200-500 mA and flatten a healthy battery in hours. A normal sleep draw for this generation is usually under 50 milliamps, so anything noticeably higher points to a module that refuses to sleep or a wiring fault pulling current.
