I know this has been the subject of several posts but I have never understood fully what this problem is and how to cure it. Can someone in very laymans terms explain how I can travel 3 miles to my local supermarket with no warning then on my return the warning is there. Sometimes I can go a week without using the car and no warning then for no reason the next day it appears. sometimes I have to reset it and sometimes it just goes away withou having to do anything. The car is 5 years old so it shouldn't be the battery but would a battery charger help?