How do you use a voltmeter on a car electrical system?

I’m looking into upgrading my car stereo system and maybe adding some ambient lighting! I want to measure the voltage inside my car, but I’ve never used a voltmeter before. Can you help? How do you use a voltmeter on a car electrical system?

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Answer provided by
Tara Malenfa
Answered on Jun 14, 2022
That sounds like a fun summer project! A voltmeter is an excellent tool to measure voltage, test electronic circuits, and make sure various components are working correctly.
Here’s what we know about using a voltmeter on your car’s electrical system:
  • There are digital and analog versions of voltmeters. The digital version is more advanced with an LED display, while the analog version uses needles.
  • Take the two probes (one red and one black) and connect the red probe to the voltmeter’s positive connector. The black probe goes with the negative connector.
  • Next, select the type of measurement you want from the voltmeter. For car batteries, typically you’ll want the DCV setting to measure the direct current. The ACV setting can be used to measure alternating current from a wall outlet.
  • Select the range setting by determining the correct voltage range for the device. Say 10-14 volts if your meter functions at 12 volts, for example.
  • Turn the voltmeter on, and test the equipment piece while using rubber or plastic insulated handles to hold onto the voltmeter’s probes.
  • Digital voltmeters will show the measurement on the LED display, while the analog device’s needle will indicate the voltage output.
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