Blue 'eye' on top of battery

[JAS21]

I've never noticed this 'eye' on previous batteries ... is it something new? ... my battery is a Panasonic MF. It's very blue, does that mean the battery itself is good, which it should be or is fully charged which hopefully it is? or something different..... thanks

[Crossy]

Got a photo?

Does it have any text indicating what it does, maybe it reports back to Panasonic by WiFi when you open the bonnet.

[WarpSpeed]

Yes, not new, a least not to the rest of the world. Bright blue indicates good charge good water level, if it begins to fade color check water, and if it has life it will come back blue again. Some brands have a green eye.

[Pomthai]

Yes, not new, a least not to the rest of the world. Bright blue indicates good charge good water level, if it begins to fade color check water, and if it has life it will come back blue again. Some brands have a green eye.

Yep, Boliden has the eye, if I remember right it was green for OK, white to charge it, black your in trouble if it's an auto ride....

Surely black means someone punched it in the face as well.