A common question mechanics are often asked is: “When should my battery be replaced so it doesn’t let me down?” Well, the answer is that it “depends” but a rough rule of thumb is that a car battery lasts about four years -maybe five- under normal conditions.
“Normal” in this case means the battery goes through full charge cycles, it is attached to a properly functioning charging system, and it isn’t providing power for a ton of accessories. As you might imagine, normal just isn’t that common. In the real world, temperature extremes, vehicle vibration, short trips down the street and an ever-increasing array of electronic devices take a toll on a battery’s lifespan.
Image by Luke Jones
If you look at a typical lead-acid, maintenance-free car battery, it’s easy to make sense of why these factors. Inside the plastic battery box are plates made of heavy materials like lead and lead compounds. These plates are suspended in a mix of water and sulfuric acid. A host of factors can disturb this arrangement and weaken the battery structure. Vibrations from rough travel can shake loose or damage the plates. Extreme heat during the summer can speed up the chemical reaction inside a battery which can shorten its life. Driving distances can affect the reaction, too. If you have a short commute or take lots of brief trips, the battery never gets fully charged. The same rule applies for motorcycle batteries.
According to BMW of Towson, Maryland, the most obvious sign of a battery that is nearing the end is that when it is fully charged, say after a long trip, that it cranks the engine slowly. A good mechanic can help check this for you. The battery itself provides other clues to whether it’s on its way out. The first is age. If your battery is older than three or four years, start expecting problems sometime soon.
In conclusion, batteries are so reliable and so simple that drivers have a tendency to forget about them. If you pay attention to the age of your car’s battery, you’ll reduce your risk of being stranded on the road. All things considered, batteries are relatively inexpensive, considering the amount of work they perform on a regular basis.