"The production year of a Bosch car battery is not printed directly as a "year", but is encoded in a code. The code is usually located on the surface of the battery, either on the side or on the cover. To determine the production date, look for a four-digit code on the battery. The last two digits of this code indicate the year of production. For example, "21" would stand for the year 2021. The first two digits represent the calendar week of production.