I had exact same problem with battery warning several days ago. I am sure I left nothing plugged in. Next day the error is gone.

However, yesterday I got an error that one of the tires is underinflated. 200 miles away from home! Start checking with i-drive and it showed that ALL my tires are underinflated.

These must be some glitches. With the tires I just reset the TPM and everything went back to normal.

I am wondering if this is related to some temperature fluctuations, we indeed got some cold air here in Northern Ca but nothing essential. It would be great to know if there is any solution to this, pretty clear that going to dealers wouldn't help unless you show that something is really faulty.