I have a 14.4V charger for my ryobi drill. It has three lights on it ...yellow on the left with no text...green in the middle with text "fully charged"...red on the right with text "fast charge". I bought my drill used from ryobi and it did not come with an owners manual. I have two batteries and one goes into fast charge mode almost immediately, when I plug it in...the other one doesn't. It just lights up the yellow and green light until it is fully charged, then the yellow light goes out. Both batteries need to be replaced, as they aren't holding a charge very long any more, but I was wondering why they don't both go into fast charge mode. Does anyone know what that means?