T Thomas

Thanks so much. Very helpful. However, this leads me to question, If only the 12v is dead (and not the HV), why would the car not start? I'm guessing it is because the instrument panel is necessary? Seems weird that the HV battery could start the engine, which could then (via braking etc) regenerate the HV battery, but that neither the engine nor the HV battery could recharge the 12v battery. I must be missing something fundamental.

Hello. New to forum. We've had our C Max Energi about a month, and had one inexplicable dead 12 v battery, which was easily recharged (jumper cables from AAA). In searching this forum, and the web in general, I've come across a variety of proposed causes and potential fixes. However, I remain unclear about the cause (bad battery, bad console software, inadvertently leaving the EV motor running, leaving in accessory mode, etc) All of this has revealed that I am quite ignorant about the basic electronics of the car-e.g. do the 12v and HV batteries share any tasks? Is the 12 v battery used only to start the car and run the instrument panel, while the HV used only for HVAC and power train? Is the 12 v recharged solely by the HV battery? Does not the engine participate in charging the 12v (traditional alternator)? The owner's Manuel provided almost no help with these questions... So, can anyone provide a reference which provides a general overview of the two batteries in the C-max hybrid/Energi? Thanks!