Ford C-Max Energi: Shut off or put in Acc mode?

One more follow-up after my return trip from Yellowstone during the last few days. My routine each day on the way home included putting it into Acc mode and then locking the doors with the key after exiting the vehicle. I noticed that the car appears to turn itself off shortly after I lock it. With this routine, I got consistent results and never had it go into its power-save mode like it did on the way there.