How to Test a Car Battery With a Multimeter

You don't need to be well-versed with quantum physics to test your car battery using a multimeter, which, in all likelihood, is one of the most-overrated attributes of car maintenance.
The battery used to supply electric energy in an automobile is rechargeable. It is often referred to as a SLI battery, which stands for Starting, Lighting, and Ignition. It has two terminals: positive (+) and negative (−). Though rechargeable, most of the batteries have a life of 3 - 5 years, after which they need to be replaced with new ones. Proper maintenance can ensure that your battery goes on for 5 years. Most car starting problems are related to battery, and therefore, being well-versed with the battery testing procedure can be of great help.

Some Precautions Before You Begin

Make sure you read the manufacturer's instruction.

Wear protective glasses, as the sparks flying in the hood can hurt your eyes.

Avoid wearing jewelry, because gold is a good conductor of electricity.

Disconnect all the cables before you go for the battery.

Most important, always keep in mind that the battery of your car has enough power to give you an intense shock.

Car Battery Testing With a Multimeter

In order to get a precise reading on your multimeter, restart it and set it to 50 volt scale. The lead should be connected to the post of the battery―and not the cable―for an accurate voltage reading. The red lead in the multimeter should be connected to the positive (+) terminal, while the black lead should be connected to the negative (−) terminal. After 15 seconds note the reading on the multimeter gage. If you have a 12 v battery, the reading should be at least 9.6 on the multimeter for the battery to take charge. If it's less than 9.6, it means it's the time to opt for a new battery.

Caution
Many people resort to the practice of shorting the battery, wherein they take a conductive object and hold one end to one terminal, while brushing or swiping the other terminal with the other end, to test it. Owing to its hazards, which includes a fatal high volt shock, it is best avoided.

If you have good observation skills, you will be able to detect the problem with your car battery by observing some changes in the car. For instance, you will notice that the lights in the car, including warning lights, are not illuminating properly, or that your car audio system is working after you turn your ignition switch to ON or ACC, but the car doesn't start.

In some case the fault can be with the cables connected to the battery, so it's wise to cross check them before jumping to conclusions.

Regular maintenance will ensure that your car battery runs for its full term. Similarly, using a terminal protecting spray can help in optimizing the life of the battery. As we mentioned earlier, being well-versed with this procedure can save you a trip to the car repair shop, thus saving your valuable time and money.
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