How to test a car battery with a multimeter?

While some car owners would rather take their vehicle to an electrician whenever they feel like something is wrong with the battery, others prefer to do the testing on their own. If you are thinking about learning to do so yourself, the first thing that you need is a multimeter that can display the needed values with high accuracy. Actually, if you chose to do it on your own, you might develop a passion for these activities that require basic technical knowledge and more importantly, you might save some money.

Testing a car battery using a multimeter isn’t rocket science, but at the same time, cannot be done by just anyone. There are some things that you should know, but if you want to stick to the basics, you can learn them right away and this article’s purpose if to show you how to do it.

Test the battery’s charge

Car batteries usually have a long life-span, but they don’t last forever. After a certain period of time, every car owner must replace the battery. Even so, it is not recommended to replace or charge it too often. Battery testing is a practical way of testing its health. It is a matter of seconds and all you need is a multimeter. If you already own one, here is how you should do it:

  •  Use the multimeter’s voltage measurement function
  •  Set it to 20V DC
  •  Touch the black terminal with the black probe and the red terminal with the red probe
  •  Turn on the headlights
  •  Check the reading

If you are not sure what does a good reading mean, read the following:

  •  12.5 V or higher – good charge
  •  Less than 12.5 V – 75% charge
  •  Less than 11.8 V – less than 25% charge

Test the alternator

Mastech MS8229 Auto-Range 5-in-1 Multi-Functional Digital Multimeter

 

If you notice that your battery discharges too often or too fast, yet you have replaced it recently, you might want to consider testing the alternator, too. In order to do this, you can take the exact same steps as before, but with the engine running. If your multimeter reads between 13.8 and 14.4 volts, the alternator works just fine. In case the reading is lower than 13.8 V, you should consider having the alternator checked by a professional electrician.

Although multimeters are capable of measuring a wide variety of values, testing a car battery’s charge is really simple and it only requires you to know these ranges and their meaning. After the check, there are a few actions that you can take, such as e-charging the battery, replacing it or having the entire system checked by an electrician to see if there is something faulty in your car that consumes more power than it should.

Having a functional battery is crucial, as it takes away all the stress and the anxiety that a faulty one causes. If you weren’t sure if it is worth investing in a high-quality multimeter, now you know that such a device is highly practical, easy to use and can help you be proactive when it comes to your car.