If I had to ballpark it, I would say that the fob was left in the ignition for approximately 30 minutes. I had done this on several occasions without consequence (at least which I was able to immediately observe).

I did this just to listen to the stereo while I detailed the inside. Apparently that was my mistake...I was informed to let it run with the engine on or don't turn anything on.

Again, it was an expensive wash and detail for me...