Many battery manufacturers and installers use a date code system to help establish warranty dates. You will often see a label on the top of your car battery that has a date code systems similar to the one shown below. The dates typically represent the month and year in which the battery was installed into your car.
The photo below shows a battery that was installed in April of 2015. Your warranty will be dependent on service range of your battery. This is typically 24, 36, or 48 months. See your battery installer for more details.