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Last Updated on July 25, 2022 by Manager Access
A portable generator can be a great tool for a variety of situations.
Whether using it as an emergency backup power source, for powering tools in a remote location, or for improving your tailgating or camping experience, it’s important that your generator is producing the correct voltage.
How can you tell? A cheap voltmeter is all you need.
Table of Contents
When using a voltmeter to test your generator’s output, it’s important to follow a few safety rules.
Ideally, you should stand on a rubber mat and wear shoes with non-conductive soles. This is just a precaution, but it is a good idea. Although it is unlikely, you could end up getting seriously injured.
It is also imperative that you don’t touch the voltage regulator or other wires at any point—or you could get a big shock.
Testing your generator’s output is really quite safe, but an abundance of caution doesn’t hurt.
1. Start your generator and turn on the voltmeter
Get the generator running. Turn on the voltmeter and make sure it is set to the “AC Voltage” position.
If you don’t have it in this mode, you’ll risk blowing a fuse.
2. Ground your meter
Using the black lead, ground your voltmeter by attaching it to the generator’s frame.
The lead should have an alligator clip you can use to attach it to the frame.
3. Touch the red lead to the output plug
Take the red lead and touch it to where you would plug in a tool or appliance.
Read the voltage displayed.
This is your generator’s current voltage output.
Troubleshooting an AVR
If the voltage wasn’t the number you were expecting, there are a few steps you can take to figure out where the problem is.
First, if your generator has an automatic voltage regulator, or AVR, this is likely the cause of your lack of voltage.
To test this, locate the AVR and remove the two leads.
Next, remove the red and black leads going from the AVR to the brush set.
Cover the red and black leads with electrical tape so they cannot touch each other or the housing.
Grab a 12-Volt DC power source (like a car battery) and some alligator clips. Hook the alligator clips to the brush set you just removed the leads from.
Then, hook the positive line you just attached to the brush set to your battery.
The positive line should always be toward the bearing. Don’t do anything with the negative line just yet.
At this point, start up the generator.
After the generator has been running for at least 10 seconds, hook the negative line from the brush set to your battery.
Now, grab your voltmeter and use it to test those first two leads that you first detached from the AVR.
You need it to read at least 60V. Often, this 12-volt battery test actually resolves the problem.
It helps restore the residual magnetism that the generator needs.
If this doesn’t work, you will likely need to replace the AVR. If the AVR isn’t the problem and your generator is still failing to produce electricity, chances are good that another more complex part has gone bad.
At this point, you should take the generator in for servicing from a manufacturer-approved technician.
Ultimately, checking your portable generator’s output is an easy and safe endeavor. A cheap voltmeter is all you need, and the process is quite simple. If you get an unexpected reading on the voltage meter, the basic troubleshooting process is a bit more complicated but still doable and safe.
Does this guide make sense to you? Do you have any unanswered questions? Do you have any other questions about portable generators? Please ask away in the comments!
Scott Krager purchased generatorgrid.com in the summer of 2020 and quickly began to buy every generator under the sun! He currently has over a dozen generators and the number is growing quickly. He lives in Portland, OR near his family and friends.