An indicator in use with a lead storage battery comprising a case and battery elements disposed in said case, said battery elements including electrolyte and a set of plates, said indicator adapted to indicate the overdischarge of said storage battery and also the lowered level of said electrolyte beyond minimum allowable level. The indicator comprises a cylindrical hollow body of transparent material with the upper end of the body exposed to the top of the case and with the lower end of the body positioned substantially at the minimum allowable level of the electrolyte, said lower end of the body communicating the electrolyte within the case. A colored float is disposed within the cylindrical body for vertical movement therein, said float having a specific gravity less than that of the electrolyte when the storage battery is charged at predetermined degree and greater than that of the electrolyte when the storage battery is discharged beyond the minimum allowable degree of charging condition. Reflective means is provided in the cylindrical body at the lower end thereof to reflect light from the upper face of the body through the thickness thereof in horizontal and vertical directions. When the storage battery is charged at more than predetermined degree, then the float is positioned in no alignment with reflective means whereby no light passes through the float with a result that the upper face of the cylindrical body is found to shine. When the storage battery is discharged beyond the minimum allowable degree of charging condition or when it has the electrolyte level lower than the minimum allowable level, then the float is positioned adjacent to the lower end of the body in alignment with reflective means whereby light passes through the colored float with a result that the upper face of the cylindrical body is found to provide a colored annulus.
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