Digital Multimeter

In any auto shop or garage, you can count on finding a digital multimeter. This a helpful tool that shouldn't just be found at mechanic shops though, but rather even at home as there are many uses for it. Many may already be familiar with digital multimeters as they're used frequently in homes to measure how much power is being used – the digital multimeter is usually used to test the circuit breakers.

What is the Digital Multimeter?
The digital multimeter is a device used for electric measurements. The digital multimeter is a composition of three different devices. The three different devices that make up a digital multimeter are: an ammeter, voltmeter and ohmmeter. Below is a bit of information about each device.

  • Ammeter – a device used to measure electric current in amps
  • Voltmeter – a device used to measure the electric potential in volts
  • Ohmmeter – a device used to measure electric resistance in ohms

Digital Multimeter Design
Digital multimeters are designed to be easy to use so you can test anything without any complications, even if you're a beginner to the device. They're also designed to be able to be roughed around and usually have a hard plastic case covering the device. There are knobs on the device that make operating it very easy.

Digital multimeters are unique for the fact that they are digital and contain a digital screen that displays the measurement results. Before you buy a digital multimeter you will want to make sure that the screen can easily be read in the sunlight. You’ll likely need to use the digital multimeter while outside (in the sun), especially if you’re using it for your vehicle.

The function switch (knob located under the digital screen) lets you change the testing mode so you can choose what to measure – ammeters, voltmeters, or ohmmeters. When picking which digital multimeter to purchase, it's advisable to select one with a larger function switch. There are usually eight different modes to choose from. You can find out what each mode symbol is for in the instruction manual that comes with your digital multimeter.

Testing a Car Battery with a Digital Multimeter
When you test a car battery you will want to make sure the digital multimeter is set to measure in volts. Testing your car battery isn't very difficult when you use a digital mutimeter but you will need to know how to do it with safety in mind. Here's a short guide that can help you with the task:

Disconnect the Battery
First you'll have to lift up your engine bonnet and grab the battery. Disconnect the cables (according to the directions in the driver's manual) and grab your digital multimeter. Make sure the cables are disconnected properly as you could cause self injury or damage to your vehicle if you're careless and don't follow the manufacturer's directions.

Preparing the Digital Multimeter
With your digital multimeter powered off, program it to a 50v scale. By doing this you are resetting the digital multimeter and it leads to more accurate and reliable results. You will now want to take the red lead from the multimeter and connect it to the positive terminal on your car battery. Do the same with the black lead as well, but attach it to the negative terminal of your car battery. Don’t place the lead on the cable, but rather the actual post so you can get a more reliable measurement.

Reading the Results
Once you have connected both leads to the battery terminals you can test the voltage. Wait about fifteen seconds for the accurate results to surface and then check what the digital multimeter is displaying on its screen. Assuming you have a 12v car battery, you'll want to have a minimum of 9.6 volts displayed on the digital multimeter screen. If you aren't getting readings that high, it's time to get a new battery.

If you are getting a reading of less than 9.6 volts from the multimeter, it may not mean your battery is no good. You'll want to determine the temperature of the battery before throwing it out. If the battery is at a low temperature then the minimum voltage that you can rely on is lower. A car battery at 3 degrees Fahrenheit would only need a reading of 9.1 volts. This will vary depending on the temperature but generally in non-extreme climates it shouldn't offset the results too much.

Use all the information provided in this article to pick a good digital multimeter to buy for your automobile. You shouldn't have any issues with following the guide for testing your car battery and it could save you from investing in parts that you don't really need. Plus, a digital multimeter is a great tool to have around the house!

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