Safety goggles for sports and work includes a frame, two lenses, two female fasteners and an elastic band. The method involves measuring a variable cell parameter for at least a part of an initial period of discharge during which the cell voltage initially decreases to a through voltage and then increases to a plateau voltage, and relating the variable cell parameter to reference information to obtain the absolute or relative charge capacity of the cell or cells. In another aspect, an improved method of evaluating responses to the encoded questions is disclosed.