The primary function of a car battery is to start your car.
Many cars have a single maintenance-free 12-volt acid battery (in the photo).
A car battery is rechargeable. It uses its charge to power the vehicle systems while parked and to turn over the engine to start. Once you start the car, the alternator generates additional electric power to recharge the battery.
Over time, a battery loses its capacity or ability to hold a charge and eventually will not be able to start your car. This happens most often when the weather gets cold. When the battery is low on charge, a car will need to be boosted to start. To avoid this situation, a battery should be replaced before its capacity drops to a critical level.
On average, a car battery lasts from 5-to-7 years.
The battery lasts longer if the vehicle is driven daily and kept fully charged. When the vehicle is parked for extended periods, the battery deteriorates sooner. We have seen the battery last up to 10 years.
How can you tell that the battery capacity is getting low? One way is to have it tested. The battery capacity is often measured in CCA or Cold Cranking Amps.
Many automotive repair shops can test your battery with a special tester (in the photo). The battery tester can measure the actual CCA and compare it to the new battery CCA rating. A battery tester can also test the alternator and the charging system.
The battery and charging system test, known as the AVR test, costs from $20 to $50.
After the test, you might get a printout showing the battery CCA rating and actual CCA. The printout will indicate if the battery should be replaced or need to be recharged. See the sample printout in the photo.