Answer:The battery is allowed to have a small amount of heat, whether in use or during charging, but abnormal heat is not allowed. The abnormal fever is obvious, and you can feel it by touching the battery case with your hand. Heat is very harmful to the battery. The heat first causes the electrolyte water to evaporate and gradually dry up, and then decreases the charging efficiency, deformation of the plates, increased internal resistance, accelerated oxidation of mechanical parts, burned out plates or separators, and finally manifests in reduced battery capacity and shortened life.