A vehicle's battery will not last forever, and without it the car will be unable to continue to run or even start. When a battery is approaching the end of its useful life, there will usually be ample warning signs and clues that, if heeded, can prevent a breakdown. Since the cost of automotive batteries is significant, it pays to look for the signs of impending failure to ensure enough time to arrange funds for a replacement.
In most cases, your car will warn you when the battery will soon need replacing. With the engine running, a battery annunciator light on the instrument panel will illuminate when the battery is beginning to fail.
Some instrument panels may have a gauge called an ammeter that shows the battery state. In this case, if the ammeter is reading near the low end, like an empty fuel tank gauge, the battery is in poor condition. The car's manual will have details on what the annunciator light or ammeter looks like, but most typically have a picture of a battery with plus and minus signs at the terminals.
A car with a failing battery will have difficulty starting up because the weakened battery will not have enough power to turn all the components in the engine. When the ignition is turned to the start position, symptoms such as cranking slower than normal and loss or dimming of internal and external lights indicate a failing battery.
If nothing but a rapid clicking noise is heard when the key is turned to start, the battery is critically low.
Periodic testing of the condition of the battery may be the best early warning of battery failure. Many auto parts stores and mechanic shops offer free bench testing of car batteries, oftentimes as part of a free road safety or road worthiness test. The battery is charged and then tested on a machine, and the results indicate whether there is much useful life left in the battery.
