Posted by Makan on 11/30/2013 to
Turning the key in the ignition, you find that your car won't start. This scenario happens frequently because car batteries provide the initial power to the starter to turn the engine over. If a battery cannot provide the necessary current, your car remains off. It is good practice to test your battery periodically to avoid being stranded. Several steps are involved to test a car battery properly and safely.
Take A Look Under The Hood
Remove the wires from the two terminals and pull the battery out. There may be a harness holding it in, however, so detach any connecting screws as needed. Set the battery on a work desk. It will be dirty and possibly corroded. Wear gloves to protect your hands from corrosion burn. Even dried granules on the battery's exterior can burn.
Inspect the case and terminals. There should be no obvious cracks or damage to the battery itself. Mix baking soda and water together in a cup. Dip a battery wire brush into the solution and remove any corrosion buildup on the terminals. Wear protective eyewear to avoid injury.
Setting Up The Test
Place the clean battery back in its original location. Inspect the loose battery wires. No cuts or cracks should appear along their length or the connectors themselves. Reattach the wires to the battery terminals by starting with the negative, or black, wire. Connect the battery harness, if equipped.
Voltage Testing
You want to start with a voltage test using a digital battery tester kit. Turn on the handheld tester and allow it to zero out. Attach the black tester wire to the negative battery terminal. Connect the red tester wire to the positive battery terminal. Read the display. A voltage reading of 12 volts or lower indicates a bad battery. It requires replacement to turn the car back on. Good batteries vary between 12.4 and 12.6 volts.
Load Testing
Your battery may indicate a strong voltage, but its ability to move current to the starter is the key to a reliably functioning engine. Detach the digital voltage tester and connect an amp battery tester to the same battery terminals, matching black to black and red to red. Adjust the load control on the tester until it reflects a value that matches half of the cold-cranking ampere rating. You'll find this rating directly on the battery's face. Turn the amp battery tester on for up to 15 seconds. Look at the corresponding voltage as the tester activates. A good battery should display 9.6 volts or higher. Any lower than that value and the battery needs replacement.
Safety Is Key
Be aware of any loose wires at all times during battery testing. Keep positive and negative wires or terminals from striking each other. You create a spark and possible fire hazard. Once you are finished testing the battery, store all test items away from the vehicle. Never leave a tester unit or part laying within the engine. It can quickly become lodged in the engine and cause significant damage.
Take A Look Under The Hood
Remove the wires from the two terminals and pull the battery out. There may be a harness holding it in, however, so detach any connecting screws as needed. Set the battery on a work desk. It will be dirty and possibly corroded. Wear gloves to protect your hands from corrosion burn. Even dried granules on the battery's exterior can burn.
Inspect the case and terminals. There should be no obvious cracks or damage to the battery itself. Mix baking soda and water together in a cup. Dip a battery wire brush into the solution and remove any corrosion buildup on the terminals. Wear protective eyewear to avoid injury.
Setting Up The Test
Place the clean battery back in its original location. Inspect the loose battery wires. No cuts or cracks should appear along their length or the connectors themselves. Reattach the wires to the battery terminals by starting with the negative, or black, wire. Connect the battery harness, if equipped.
Voltage Testing
You want to start with a voltage test using a digital battery tester kit. Turn on the handheld tester and allow it to zero out. Attach the black tester wire to the negative battery terminal. Connect the red tester wire to the positive battery terminal. Read the display. A voltage reading of 12 volts or lower indicates a bad battery. It requires replacement to turn the car back on. Good batteries vary between 12.4 and 12.6 volts.
Load Testing
Your battery may indicate a strong voltage, but its ability to move current to the starter is the key to a reliably functioning engine. Detach the digital voltage tester and connect an amp battery tester to the same battery terminals, matching black to black and red to red. Adjust the load control on the tester until it reflects a value that matches half of the cold-cranking ampere rating. You'll find this rating directly on the battery's face. Turn the amp battery tester on for up to 15 seconds. Look at the corresponding voltage as the tester activates. A good battery should display 9.6 volts or higher. Any lower than that value and the battery needs replacement.
Safety Is Key
Be aware of any loose wires at all times during battery testing. Keep positive and negative wires or terminals from striking each other. You create a spark and possible fire hazard. Once you are finished testing the battery, store all test items away from the vehicle. Never leave a tester unit or part laying within the engine. It can quickly become lodged in the engine and cause significant damage.
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