How Do I Know If My Car Battery Is Bad?

Most of us get in our car every day and turn the key in the ignition without any thought of whether it is going to start. A car's battery is a vital part in the starting process, but it is something that is too often overlooked. Sometimes an unresponsive car can be fixed by simply adding water to a battery. There are other ways to determine if your car's battery is causing it to fail to start.

Things You'll Need

• Voltage meter
• Eye protection

Instructions

Testing A Battery Without A Voltage Meter

1. Turn the key to the accessory setting in your ignition. This is the setting that allows you to play the radio and turn on other accessories, such as the windshield wipers.

2. Turn on the windshield wipers. If they run more slowly than normal, the battery does not have enough of a charge.

3. Look at the instrument panel lights. If they are dimmer than normal, the battery's charge is not adequate.

Testing A Battery With A Voltage Meter

1. Turn your car off and don't drive for at least eight hours. Open the hood and remove the battery terminal covers.

2. Connect the positive (red) cable on a voltage meter with the positive (red) battery terminal of your car. Connect the negative (black) cable on the voltage meter with the negative (black) battery terminal.

3. Look at the reading on the voltage meter. A properly-functioning battery will produce at least 12.5 volts on the voltage meter.

Tips & Warnings

• The lifespan of most batteries is three to five years, so a battery that is at the end of that range will probably need to be replaced. Batteries that are less than three years old and are run down can be charged.

• You can remove your car's battery and take it to an auto parts store for a free diagnostic test. The auto store staff will connect your battery to a voltage meter to determine whether it needs to be replaced.

• Remove all jewelry and wear eye protection when using a voltage meter to test your battery. Jewelry can conduct electricity.

References

• Samarins: Car No-Start Troubleshooting Guide
• 2 Car Pros: Checking A Battery