How do car batteries work?
Although the technology has not changed greatly over the years, the use of a battery has expanded. As most commonly known, the battery provides the necessary burst of electricity to start the car’s engine, sending it down the cable to power the starter motor, which then turns the flywheel. In addition, the battery provides power when the engine is not running. Lights and security systems stay on after the engine has been shut off. On board computers also perform many basic diagnostic functions while the car is not in use. Last and least known, the battery acts as a giant capacitor. It easily absorbs any a/c current produced by the alternator but not rectified (converted) into d/c current. Electrical components need d/c current to work, but will perform poorly or break down if exposed to a/c current. The battery shields these sensitive electrical components.
On average, when will you need to replace your battery?
Most car batteries will last an average of 4 to 6 years depending on the quality of construction. As the battery is used to start the car and to provide power when the car is not running, the number of starting cycles or key turns is more instrumental to the longevity of a battery than the months or years. Extremes of temperature, engine vibration, worn starter motor and the addition to high draw after-market electronics will also affect the length of useful battery life. Ultimately, the most proactive approach to predicting when to change a battery is to have it load tested when in for other service. A load test will place the battery under similar conditions to how the starter does, where a more accurate measurement of the battery state can be obtained. A battery that falls below 9.5 volts under this dynamic test should be replaced.
What happens if the battery is not replaced on time?
If a car battery is not tested regularly, and not changed when recommended, several consequences will result. The most painful will be the lack of sufficient power to start the car. Jumping the car with another battery can temporarily resolve the problem, if the bad battery can still accept a charge. If the battery cannot hold a charge or if the battery has been drained or discharged fully, the alternator may have to work harder to keep up with the power needs of the car and the attempt to recharge the battery. This may cause a failure or shorten the expected life of the alternator. Moreover, as the battery fails to supply engine off power to systems, keep alive memory, stored figures and numbers will be erased, causing drivability issues (air-fuel ratio calculations, shift points, idle values), where the car will run poorly. In a worst case scenario, key codes could be erased, the anti-theft computer will not recognize a key resulting in a no start until a reset with an appropriate factory computer is performed and values restored.
Most automotive service professionals can perform this service. Keep in mind, pricing will vary by location and your vehicle make and model. Use Openbay to compare battery replacement costs with top repair shops in your area.
Service article written by an ASE Master Technician