I got the red light dashboard special yesterday morning. Red battery icon and the message. It was 4 degrees out when I got into car having parked overnight on the street. I did not stop but my passenger retrieved the manual and read that this message meant that the 12V battery was not charging and to see a car specialist. As I was headed to the dealer for my every other day charge and was 3 miles away, I decided to keep going and made it to the dealer. They charged the big battery and checked for shorts and the 12V battery and found nothing awry. He suggested that the battery had partially frozen overnight and that might have triggered the message 15 minutes into the drive. I am monitoring and will have them take another look next week when I am in for my charge. I am not sure what the 12V battery powers but I would think it is more than the radio and AC. I turned both off when the message popped up and the message turned off a couple of minutes later or was overridden by the Reserve Battery message indicating I had less than 5 miles left. I rolled into dealer with 1 mile left.
Coincidentally, my wife reported a similar message on her E500W later in the day and it also went away. The original 7 year old battery was replaced about 6 months ago. It is parked inside an unheated garage where the temperatures were likely below freezing too overnight.
Coincidentally, my wife reported a similar message on her E500W later in the day and it also went away. The original 7 year old battery was replaced about 6 months ago. It is parked inside an unheated garage where the temperatures were likely below freezing too overnight.