Your car battery is the strong, silent member of the vehicle. It does its job regardless of heat, cold or a driver who demands so much of it. While the battery that allows your car to start at the first turn of the key is a joyful thing, it will not last forever.
In fact depending on where you live and how you drive, the condition of your charging system, plus other factors, a battery may last 4 YEARS on average. There is generally no sign of trouble - it just gives out and your car dies.
While that basic design of the battery hasn't changed in the last 100 years, the simple rule of thumb for battery replacement is approximately four years.