Battery date codes are alphanumeric codes printed onto marine, automotive and other batteries that tell a user when the battery was shipped from the manufacturer. Battery date codes are typically four or five digits in length.
Battery date codes typically are found on the tops of batteries, usually in one corner, and can only be seen when looking straight down at the tops of batteries. The first two digits in the date code are the most important. These are the digits that indicate both the month and year when the battery was shipped. The first digit is the month, indicated by a letter (A is January, B is February, and so on) and the second digit is the year (1 is 2011, 2 is 2012, and so on).