I got the excessive battery drain message and took it to the dealer. They performed the tests suggested by the SIB but didn't find a fault (they updated everything while they had it anyways). Their conclusion was that I was not driving it enough as I mostly drive stop and go for short distances.

Their recommendations were (1) to drive the car at least once each week for at least 30 min and (2) they gave me a charger and told me to charge the battery if I was not able to do #1.

I've never had a car that needed to be plugged in even though my commute has been the same for many years.

Of note, I was working on my other car (08 M3) this weekend and noted that the X5 wakes up periodically with electronic sounds and then shuts off. It makes me wonder if the X5 electronics run in sleep mode while the car is off.

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2012 F10 550xi Carbon black/oyster
2011 E92 M3 SSII/black
2012 W166 ML63 Steel grey/porcelain
2007 E93 monaco blue/beige (retired)
2010 E70 35d Space grey/saddle brown (retired)