Funny story about those green eyes...
My friend used to own a store that sold every battery from wristwatch batteries to 8D's. It was called The Battery Terminal. He always had a Delco battery on the counter that he had sawed away most of the housing but left the cell with the eye intact. It would be green. Whenever he tested a battery and it would test bad and then the customer would say but the eye is green, he would direct their attention to the butchered battery and say I'll give you this one free. The eye is green. They would then agree a bad battery could have a green eye.