Abstract: An electric storage battery comprising a closure sealed with a battery casing and having gas venting means which allows gases from cells to be vented out of the storage battery, but which prevents electrolyte mist and water steam from the cells carried together with the gases to be leaked out of the storage battery. A gas cooling chamber is provided on a battery cover of the closure and has a water returning cylindrical portion provided on a bottom of the gas cooling chamber and having a water returning lateral port adapted to return the water. A gas filter chamber is provided adjacent to the gas cooling chamber to communicate with the gas cooling chamber through an opening in the wall of the gas cooling chamber at the top thereof and has an explosion-proof gas filter of porous ceramics provided to vent gases therethrough.

Abstract: 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.