The signs and symptoms of a car battery going bad are similar to other problems that can occur under the bonnet, making it mostly a matter of guess work to tell whether or not you're dealing with a faulty car battery. If your car exhibits one or two symptoms of the following symptoms, it does not mean your car battery is the problem. However, the likelihood of a dead, dying or faulty car battery increases as more signs present themselves.
Examine your dashboard warning lights. Most cars have a light indicating that the battery is faulty or going bad. If your battery is on its last vestiges of life, the dashboard battery indicator light may be on or flashing. While the battery warning light is not always indicative of a dying battery, it does appear at the first signs of a problem with the battery and should be examined by a mechanic when possible.
Keep an eye on the electrical systems of your car, including the headlights, radio, fuel injection system and heating or air conditioning. When a battery is going dead, all of these things lessen in function while the car is running. The more electrical items that are running, the harder it will be to start the car and keep it running. If your radio still turns on but the car doesn't, you may need to recharge or replace your car battery.
Car Won't Start
If your car doesn't start or has trouble starting, the battery may be going bad. When you turn the key in an attempt to start the car, you might hear a noise that sounds like clicking or ticking. This is a strong indicator that your battery, and not the car's starter or alternator, are the problem. Try starting the car with the assistance of jump leads. If it still doesn't start, the problem is most likely the battery.
Be aware of the lifespan of your car's battery. Most car batteries last from two to five years, with some greatly exceeding this expectation. If you have had the same battery for more than five years and your car exhibits the symptoms listed above, your car's battery may be on its last leg. Have the battery tested by a mechanic or auto parts store to see if the battery is still viable. Alternately, cars that have been sitting for quite some time may also have a faulty battery. Not turning on the car or using the battery greatly decreases its lifespan.