There is nothing quite as disappointing as getting out on a great day of riding your quad only to have the battery suddenly die. There are several reasons your ATV could suddenly stop working, and it seems many people point their finger (rightfully and wrongfully) at the stator.
But, how do you know if your ATV has a bad stator? If your stator is bad, the battery of your ATV will not charge while the ATV is running. This can be caused by several other problems, however, so the only way to be sure that your stator has gone bad is to perform a series of tests using a multimeter.
In this article, you’ll find everything you need to know about your ATV’s stator, including what it is, what it does, and how do you test to see if it is bad.
What is a Stator and What Does it Do?
A stator is an electrical component of ATVs that is responsible for recharging the battery while the ATV is in use. Think of it like your car’s alternator.
Stators can look quite different depending on the brand of ATV and model, but in general, they consist of an iron core, wire coils, and a cable that allows the stator to be connected to the voltage regulator.
Magnets spin past the coils, which creates an electric current in the wires, which is then passed along to the voltage regulator, and then charges your battery.
Types of Stators
There are three different types of stators:
- Single Phase Stators: Not as powerful. Uses a single wire to create the coils that circle the iron core. You will see two wires in the cable coming off the stator.
- Three Phase Stators: Most ATVs use a three-phase stator because they are capable of producing more electricity. It uses three wires to create the coils that circle the iron core. The cable coming off the stator will clearly have three wires (usually yellow, but not always) if you have a three-phase stator.
- Bar coiled stator: This is a compact stator with coils arranged and attached to a backing plate. The coils are attached to bars and not an iron core. This type of stator is more common in older ATVs.
Extra Components on Stators
The stator’s primary job is to recharge your ATV’s battery while it is in use, but many ATVs have stators capable of doing more. Your stator might include one or more of the following:
- Crank position sensor: This is a small boxy component that should be attached to the stator at the cable. Some people also call this a pick-up coil.
- Specialty coils designed to power the ignition system directly: These coils are usually protected with cloth and/or epoxy, and look strikingly different from the other coils.
- Grommets and other mounting components: These will vary depending on the design.
So, looking up a picture of a stator won’t tell you what your specific stator should look like. The best place for that information would be your service manual.
Signs Your Stator is Bad
If your stator is bad, your battery will not charge while you’re driving the ATV. Unfortunately, this can be caused by a variety of other issues with your ATV. Stators tend to be reliable, so before you go replacing the stator, check on these other components:
- Your battery: Will the battery charge if you put it on a separate charger? Is the battery old or corroded? It is easy to have a battery checked at someplace like Autozone for free so I recommend doing this first.
- Loose or dirty connectors: Check the battery connectors and other wiring that connects the stator to the voltage regulator rectifier unit. You may need to clean the connectors. This is a free and easy fix so try it out if your battery is still good.
- Voltage regulator rectifier unit: If your voltage regulator is bad, you’ll have the same problems as if your stator is bad. This can make it difficult to determine, which is the problem. You can test this with a multimeter to see if it is working.
If you’re battery, wiring, and voltage regulator are all working correctly, then it is time to check the stator. Some people opt to replace the stator without checking, but testing a stator is easier than replacing it as long as you have a multimeter.
You can get a multimeter for $10-40 on Amazon, so you might as well just have one around for when you need it.
How to Test a Stator
In order to test your stator, you only need two things, neither of which is expensive.
- Multimeter: You don’t need a fancy multimeter, just one that can measure AC and DC output and ohms.
- Service manual: If you no longer have your ATVs service manual, you should be able to find one on the manufacturer’s website. Just make sure you have your model number handy.
Once you have these two items gathered, you will need to perform some tests to see if your stator is working properly. Your service manual will give you the best information on how to do this, but we will go over the basics below.
For the resistance test, you’ll measure the ohms. You don’t need to worry about which meter lead you use with which pin because polarity doesn’t matter for this test.
- Make sure your ATV is off. Disconnect the stator cable. You should see the three wires of the same color running out of the stator to the connector.
- Turn the multimeter to ohms.
- You’re going to place the meter leads to the pins in the connector. You’ll test each combination of pins. It is helpful to number them mentally for this. Test pin 1 with pin 2, pin 2 with pin 3 and pin 1 with pin 3.
- For each combination, you should note what the reading is and compare it to the reading that it should be, which is listed in your service manual.
- If your reading is not what it should be according to your service manual, then your stator should be replaced.
Insulation Break Down Test
This test makes sure that the stator isn’t shorting out to the ground.
- Place one meter lead in the connector and the second on the body of the stator
- Your meter should read “OL” or open line. If the multimeter is picking up a reading, it means your stator needs to be replaced.
- Repeat this test for each of the windings.
Testing with the Motor Running
When testing the stator with the motor running, you’re going to need to make sure that the battery already has some charge in it. This can be easier said than done when your battery’s charging system isn’t working!
For this test, you’ll measure the volts of AC coming out of the stator while the ATV is running at an rpm determined by your service manual.
You’ll basically do the same thing listed above, but with the motor running at a set rpm. You’ll need a friend to help you with this!
How to Fix a Bad ATV Stator
If your ATV’s stator is bad and you aren’t a master at working with electrical components on vehicles, then you’ll have to replace the entire stator.
Stators aren’t usually expensive for most ATVs. They will usually cost under $100 for the part and can be significantly less.
The job itself isn’t usually too intense as the stator is typically mounted to the engine in such a way that it is somewhat easy to access. Of course, this will depend on the design of your ATV.
Whether you decide to do the job yourself or hire a professional, it shouldn’t set you back too much.
Unfortunately, replacing a stator is going to be unique, depending on the design of your ATV, so we can’t give you much guidance on how to replace it. The idea is simple, though: remove the old one and attach a new one. Put it all back the way you found it, and you’re done.
Stators can and do go bad, but it isn’t a common occurrence. The only way to know if it’s your stator is to test the stator itself. Luckily, testing is simple. Even those who aren’t mechanically inclined can test their stator by referring to their service manual and following the steps outlined above. So if you aren’t sure, do the test.