I don't understand why the light goes on when I am away from the car, it is locked, plugged in and it is fully charged. I thought the light stayed off when the car is locked. At first I thought it turned on because it was making up for vampire losses. But this time, after being fully charged I returned from a short trip and set the charge limit significantly lower than the current charge level, plugged it in, and the green light comes on for a minute or so every once in a while hours after I leave the car. Has anyone seen this behavior before? Do you know why it is doing this?