This presentation has been developed as a aid to those wishing to determine the date of manufacture or warranty date for a cell or battery. Manufacturers sometimes code dates using letters and/or numbers that are not easily understood by those responsible for the battery system. This presentation attempts to provide those persons with a guide when needed to determine the date code. Date codes are sometimes changed by the battery manufacturer and there is no guaranty that the information needed is contained in the presentation; however, it may help in ultimately identifying a date code, either with help from the battery manufacturer or using the information presented to interpret what one observes. The information contained in this presentation does not include every battery type or manufacturer.