How to Use a Voltmeter to Check Your Portable Generator’s Output

Last Updated on July 5, 2022

Do you own a portable generator? You must find it invaluable. Yes, a portable generator can be a great item that you will use in a variety of situations. It could be that you have to power tools, and you are far from the nearest power lines.

Or perhaps you require a power source as an emergency backup. It might be that you are camping or are in a tailgating expedition and want to keep things going. In all these situations, a portable generator is just what you need. Make sure that your generator has the right voltage.

However, how can you tell that the voltage is right? You only need a volt meter to do that. It doesn’t have to be costly. A cheap voltmeter will do just fine. Meanwhile, as you do this, remember that your safety comes first.

Safety First

It is vital to follow a few safety rules when using a voltmeter to gauge the voltage in your generator. Here are a few useful tips:

  • It would be wise to step on a rubber mat and wear non-conductive- sole shoes. This is an excellent precaution to guard against possible electric accidents that can harm you.
  • Avoid touching the wires located at any point because this could lead to electric shock. You especially need to avoid touching the voltage regulator for the same reasons.

It is essentially a straightforward process to test the generator output. Nevertheless, you must exercise great caution to forestall dangers or the possibility of fatal accidents.

Steps to Check Your Generator Output

Follow these simple steps:

  • Turn on the voltmeter after first starting the generator.
  • While the generator runs, turn on the voltmeter. Make sure the voltmeter is set to the “AC Voltage” position. Unless this is done, you risk blowing a fuse.
  • Ground your meter. Do this using the black lead. To do this, attach the meter to the frame of the generator (if it grounded!).
  • There is an alligator clip found on the lead. This is useful for attaching the meter to the engine frame.
  • Attach the red lead to the output plug.
  • Touch the red lead to the place where you want to plug in the appliance tool
  • Read the displayed voltage.

Note that whatever is indicated in the reading is the current voltage output of the generator.

Troubleshooting the AVR

If you find that the voltage reading is below expectation, you can take some steps to remedy that:

  • Does your generator have an automatic voltage regulator (AVR)? This might be the cause of the low voltage.
  • Test this by locating the AVR and removing the two leads.
  • There is a red and black lead going from the AVR up to the brush set. Remove the leads.
  • Cover the two leads with electrical tape. This will prevent them from touching each other or touching the housing.
  • Get a 12-Volt DC power source. This can be a car battery and alligator clips. Hook the clips to the brush set that were removed from the leads.
  • Set your battery by hooking the positive line that you just attached to the brush set.
  • Ensure the positive line is always set towards the bearing. At this stage, leave the negative line alone.
  • Now start the generator.
  • Let the generator run for some ten seconds then hook the negative line from the brush that is set to the battery.
  • Take your voltmeter. Use it to test the first two leads that were detached from the AVR.
  • Try to make it read 60v. Many times, a 12- volt battery test is enough to resolve the problem. You will find that the residual magnetism of the generator is restored through this test. That is all that is needed to fix the problem.
  • In case this fails to work, you might have to replace the AVR. If the AVR is not the reason for the low generator output or lack of power, it could be that another part of the engine is faulty.
  • If some other part of the engine is causing problems, you will have to take the machine to a qualified technician for service. Make sure the manufacturer approves the selected technician.


It is quite easy to check a portable generator’s power output. All you need is a cheap voltmeter. It is a simple process. In case you get an unexpected reading on your meter, follow the necessary troubleshooting process to remedy the issue.

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