Me too. I have a Ford CMax Energi that 3 times over about a year when I go to drive it, it's completely dead. Here's what I've gathered from the internet so far, which please correct me if it's wrong: 1. Lots of Energi owners are having this problem. 2. Two possible cause of the problem: a. FOB battery dead - fix is to insert FOB into steering column as per instruction manual. b. Low voltage battery has gone dead. 3. The Low voltage battery going dead problem is caused by a defective ACM, which draws 400 mA from the low voltage battery until it goes dead, whereupon the low battery needs to be replaced, because once any lead acid battery (low voltage battery is lead-acid) is deep discharged, it's ruined. (Ford technician: Removed Fuse # 79, 400 mA draw down went away. Fuse 79 powers ACM and FCIM. Disconnecting FCIM: no change. Disconnecting ACM: 400 mA draw down goes away. 4. The fix for the low voltage battery problem is replace the low voltage battery and also the ACM (audio control module).
