Hi, I assume that the C-Max Hybrid only has the Lithium-Ion battery pack, and does not have a 12-volt battery as with non-hybrids. So, when you say to charge the battery, I continue to assume that you are referring to the Li-ion one. I'll discuss that with the service department when I head to the dealer as Laurel suggested. Thanks!
The C-Max has two batteries, a 12 volt and the Lithium battery. The 12 volt system is the one that has troubled many of us.
There are several discussion threads about the 12 volt problem in this forum. The biggest thread with the most information is in the section on Maintenance, TSBs, and Recalls. That is a long thread, but many of the messages are short and once you start reading you will pick up speed.
There have been several TSBs (Technical Service Bulletins) advising service departments on how to try to handle 12 volt problems. You will find them discussed in the other threads. There are TSBs for the battery ccharging software, for the entertainment screen, for the main engine wiring harness, and also another for the Body Control Module. Some people have not had repeat symptoms after one or another of these repairs, but others have had all of the repairs and still have been hit with dead 12 volt systems. Thus it seems Ford has not yet definitively identified and solved the problem.
By learning as much as you reasonably can you will be in a better position to evaluate whether your service department is doing a good job. At the very least, let them know that you know there are several TSBs related to 12 volt problems and let them know that you know this has afflicted quite a few CMax's. Ford HQ knows it, too.
The problem is not caused by how you drive the car. If anyone at the service department tries to tell you that you should go to another service department and immediately call Ford's central Customer Care number about it.
Hope your case is one that does not happen again. You won't know until a year or two goes by without further incident. Until then, keep good records, bring the car to the dealer for service whenever it happens, and, also, if it happens again have Ford Roadside Assistance tow the car to the dealer (unless you need to drive it immediately).