Whatever happened to the battery eye?

[ffhdriver]

Originally Posted By: SHOZ
Don't they just indicate the level? no.

 

[kc8adu]

they are a simple hydrometer in one cell.can help determine overall state of charge/electrolyte level but only a 1 in 6 chance of telling you the battery has failed.
i would never pay extra for one and with caps one can test with a real hydrometer with a much greater accuracy.
so its rather useless.
the average car owner never even checks oil much less a battery.

 

[NYEngineer]

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.