How To Test MacBook Charger With Multimeter?


Is your MacBook not charging quickly? Or does it not turn on when you press the power button? The culprit may be your charger. Most of us have several MacBook chargers lying around the house, and it is hard to know if they are all safe to use. The best way to check whether a MacBook charger is working is using a multimeter.

  1. Plug the MacBook charger into an outlet 
  2. Put the black multimeter cable into the COM port and the red into the VΩmA port
  3. Switch the multimeter on at the DC signal
  4. Insert the red positive conductor of the adapter pin inside
  5. Put the negative black conductor on the top of the adaptors edg

Still confused? Keep reading this article to learn how your MacBook works with a multimeter.

How Do I Test a Charger With a Multimeter?

Plug the charger into the main plug and turn it on. Put the multimeter’s black cable into the COM port and the red into the VΩmA port. Switch the multimeter on at DC signal. Insert the red positive conductor of the adapter pin inside. Put the negative black conductor on the tip of the adaptor’s edge. 

You will see a reading on your multimeter. When it comes to testing chargers using a multimeter, there is a general step-by-step process to follow regardless of make or model. Read the detailed steps below:

  1. Ensure your charger is plugged into the mains plug and is switched on.
  2. The multimeter will come with two leads. One black and one red; the black lead should go into the COM port (standing for common), and the red lead should go into the VΩmA port (an acronym for voltage, resistance, and current). The black wire is negatively charged, and the red wire is positively charged.
  3. Now it is time to switch on your multimeter by turning the tab to the DC signal.
  4. Grab your adapter pin and insert the red positive conductor inside, ensuring it touches the pin.
  5. Grab your negative black conductor and place it on the outside tip on the edge of the adaptor.
  6. Finally, this should produce a reading on the multimeter indicating whether the charge is safe. A reading of around 19V is optimal!

This easy step-by-step process is a great way to ensure all of the chargers you are using for your MacBooks are safe and reliable.

Want to keep your MacBooks battery healthy Read my ultimate guide on MacBook battery health here.Opens in a new tab.

Note: It is good to use Apple’s genuine chargers; as Apple says, using a cheap third-party alternative can be dangerous. However, you can’t go wrong picking up a high-quality third-party charger on Amazon with good reviews. 

How Do I Know if My MacBook Charger Is Working With a Multimeter?

When you plug in your MacBook charger with a multimeter, it will show how much electric potential your MacBook charger delivers. If it has the same or nearly the same electric potential in volts as it says on the MacBook charger, then your charger is working fine with the multimeter.

Multimeters are a great way to check if your chargers are safe to use; they measure the electric current, voltage, and resistance. Investing around $12 on a digital multimeter could save you from buying needless chargers and lots of money; you can pick one off for a bargain on Amazon.Opens in a new tab.

You can see a tutorial on Youtube on how to use a multimeter here.Opens in a new tab.

Generally, MacBooks require different chargers depending on the model. However, the testing process is very similar. All laptop chargers have two parts:

  1. The main plug — this goes into your plug socket
  2. The adapter — this goes directly into your MacBook

It is important to check the voltage on the adapter to ensure it aligns with that on the multimeter. 90V is the required voltage for the majority of MacBooks. However, the model may cause this to differ slightly, because the AC (alternating current) takes 240V from the mains socket and converts it to a more sensible DC (direct current), safe for your MacBook.

Note: A reading of over 240V reflects a dangerous charger, and you should throw it away.

Want to learn more about MacBook chargers? If so, please read my complete guide to MacBook chargers.

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