The age of a car battery can be determined using the battery date code. The code is
a two-digit code stamped into the cover as part of a longer code or on a battery's
top or side label. The battery date code indicates when the battery was shipped from
the manufacturing plant and is read as follows:
Letter - indicates in which month the battery was manufactured
(Example: A is January, B is February, C is March, etc.)
Digit - indicates the year in which the battery was manufactured
(Example: 9 for 2019, 0 for 2020, 1 for 2021, etc.)
For example, an automotive battery date code that starts with "B1" would be February
2021. In February 2027, this battery would be 72 months old.