A multimeter can check various current properties. You will only need some of the functions available in the multimeter for your automobile battery issue diagnosis. Voltage is one of the measures you get with your multimeter. This voltage test shows if your battery is in good condition or not. This post will tell you the right multimeter setting for a 12V car battery.
We shall consider how you should approach the diagnosis. You will know what should be the electrical position of the car before and during the test. Also, this post will tell you the meaning of different readings about the condition of the battery.
Let’s start.
What Setting Should My Multimeter be on for a Car Battery?
Even if you are using a multimeter that is designed specifically for automobile diagnostic and troubleshooting, you will have a hard time, understanding the settings you need for conducting these tests.
Multimeters perform numerous functions. As their interface allows you to deal with all of these functions and tests, the interface is a bit overcrowded for most multimeters. Because of this inherent complexity, it’s not always easy to understand the unit. And if you are a beginner, you would want to consult a pro to understand its operations.
A multimeter allows you to test voltage, current, resistance, and frequency. But for every one of these electrical elements, you have to change the settings on your meter.
The basic test you would perform on your car battery is for voltage. You first have to switch the meter to DC voltage for this test. On a multimeter, these electrical elements are denoted with symbols. If you are confused about these symbols, worry not. This post will explain the DC volt symbol to you.
To find DC volt, you have to search the ‘V’ symbol. This V will be accompanied by a short line. And this line, in turn, will have a dotted line beneath it.
On your multimeter, you will also see a V symbol that is followed by a wavy line. This symbol represents AC voltage.
What do I Set My Multimeter on to Check a 12-volt Battery?
Once you set the multimeter to read DC voltage, it’s time to set the range of voltage you need to measure.
If your multimeter is auto-ranging, the operations will be slightly easier for you. In that case, you will not have to select the range for voltage testing before checking your automobile. At the same time, the meter will take the guesswork out of your operations during any other testing of electrical appliances.
But you have to be more vigilant if your multimeter is manual. If that is the case, you must know the right range for checking your battery’s voltage. You can test the electrical output from your car’s battery using 20V as the standard voltage. Turn the knob of your multimeter so it faces 20V; then check the voltage.
But the voltage reading will only be accurate if you have drained all surface charge from the battery. You can drain this charge before using your multimeter by turning on the headlights for about two minutes. After this time, turn off the lights and start the voltage test.
How to Test My Car’s Battery Amps with a Multimeter?
The next step is to measure the DC voltage. You have to use the probes that have arrived with your multimeter. Make sure you have gotten rid of the surface charge. You don’t have to start the car; the vehicle battery should rest. Now connect the red probe with the positive terminal and the black probe with the negative terminal.
The multimeter should show a reading between 12.2 and 12.6 volts for a fully charged, healthy battery. If you want to troubleshoot the battery, you should start with charging it. After charging, it should show readings in a given range. In case, you don’t get the mentioned reading even after fully charging the battery, suspect that the battery has some issue and needs replacement.
After testing the resting voltage, your next step is to test it on the crank cycle. You have to start the ignition to take this reading. This measure will test the voltage when the battery is facing the most draw. It will show how it will perform when higher energy is needed by the vehicle to start running.
This test is conducted by two people. The other person has to start the ignition. When the ignition is turned on, you will see a quick drop in voltage reading. Note that the reading should remain above 10V. If the voltage falls below 10V, it indicates a lack of turnover strength needed by the battery. In short, it’s an indicator that the battery is malfunctioning. If the battery is fully charged, you need to replace the battery to get one with the right level of turnover strength.
After this drop in voltage that accompanies the crank cycle, your vehicle will begin to idle. You will see a steady draw from the battery in this phase. The multimeter should show a voltage range of 14 to 14.5V. Again, a drop below this level indicates an uncharged or faulty battery. It may also indicate a failing alternator.
You may want to proceed with testing the alternator to accurately diagnose the source of the problem. Here is the complete procedure to do so.
Testing the Alternator
An alternator is the source of energy for your battery. It uses chemical energy and converts it into electrical energy to keep your battery charged during running. If the alternator is not in good condition, your vehicle may not run.
You can test the alternator with the help of your multimeter. First, you have to switch on all the electrical equipment in your car. This includes its headlights, climate controls, lights, and stereo. This equipment will increase the load on the battery, allowing you to assess the voltage under pressure.
While you turn on all the equipment in your car, keep an eye on the voltage reading. It shouldn’t drop below 13.5V. If this drop happens, your alternator is not properly charging the battery. It appears that the fault is in the alternator. You can get it thoroughly checked by an experienced mechanic.
Take Away
Car battery makes an important part of the reliability of your car. It may decide if your car will run on a given day or not. It will also decide if your car will break down in the middle of an important journey.
You want to ensure that this battery remains in good condition. Also, you don’t want to embark on any journey in your car without ensuring that its battery is fully charged. In addition to maintaining a strong and reliable battery, you would also need to ensure the health of your car’s alternator. Together, the two components will ensure the longevity of your car’s life span.
You should check the battery and alternator of your car from time to time. Use your multimeter to do so. Luckily, the process is so easy that you can complete the test on your own. This post details the complete process of testing the battery as well as the alternator of your car.