That is a deceptive light. It actually has nothing to do with battery condition. What is means is that the battery is not being recharged at the time which is usually a bad alternator but could be other issues.
November, 12, 2010 AT 5:13 PM
I got your private message but all question responses need to be made here. You should see whatever the current battery voltage is with the engine off and with the engine idling and no accessories on, you should see between 13.5 and 14.8v.