Suggest you add the year and engine to your signature.

Depending on the engine there is a power steering hose that runs from the pump up and in front of the alternator. It is possible that power steering fluid got on the alternator.

Number of years old usually determines the life span of the battery. Depending on the quality of the battery, conditions of the environment and normal load on the battery and as a general rule, it could fail anytime after 3 years.

Suggest you have the battery load tested. A load test is the way to determine a good or bad battery. As Upallnight posted a resting 11.5 after the vehicle has been running for a half hour or more, with a good alternator indicates a bad battery.

If you unlock the cluster you can monitor the alternator output. If the alternator output is consistently in the range of say, 13.8 to 14.3 it is probably OK though it could have stopped charging for a time due to power steering fluid getting into it.

I think the best practice is that there are no coincidences when something like this happens. BMW electronics do strange things when the voltage is low. Are there any other low voltage symptoms?

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas