Unanswerable without a lot more information. First is where you live. Warm weather is what does the most damage to batteries. So why do people in the north always blame cold weather for being the cause of their battery failure? Because the heat of the summer damages the battery and the extra stress of starting the car in the cold pushes it over the edge.
On average, batteries last one to two years longer in the colder regions than in the hot south. So the average temperature where you live could have an extreme affect on how long your battery will last.
Next is battery CCA (Cold Cranking Amps). CCA is the measurement of how much work a battery can do during the starting process. Starting a car will draw more electricity from the battery then anything else it will ever be required to do. The higher the CCA the more power the battery can deliver. So if you have a car that requires a 500 CCA battery and you install a 750 CCA battery it will not work as hard to start the engine and will last longer. But if your car requires a 500CCA battery and you install a 250 CCA battery that battery will struggle and wear out much faster.
Then comes RC (Reserve Capacity) which determines how long a battery can maintain a small load, like computer memory, and still maintain a minimum voltage. The higher the RC rating the longer the battery can maintain the various loads applied to it when the car isn’t running and still be able to start the car. A low RC rating could mean the battery goes dead while sitting and that is very stressful on the battery and causes shortened life.
There are also differences in battery types which must match the requirements of the vehicle. Wrong battery type, shorter battery life.
How many times the battery is discharged to where it won’t start the car or deep cycled to where it won’t light the lights. The more discharges and the deeper the discharges the shorter the life of the battery.
How well your charging system works. If the voltage isn’t kept within a tight range the battery will likely overcharge and fail prematurely. Dirty (electrically dirty) battery cable connections are a common cause of over charging. Physically dirty battery cases are another cause of overcharging.
Other things that affect the life of a battery are: if the car was reprogrammed when a new battery was installed (applies to some but not all cars), was the heat shield replaced with the new battery or thrown in the trash because it is a pain to reinstall, the number of times the car is started over the life of the battery, how difficult the car is to start, etc., etc.
So battery life 2 years to 10 years but the average is 3 to 4 years.
