Has the Stator or Regulator Rectifier Gone Bad?
One of the most common questions the Partzilla.com call center staff gets is whether to replace both the regulator rectifier and the stator at the same time when a powersports vehicle isn’t charging anymore.
Doing so could probably solve the charging problem, but do you really need to replace both? Before you order both parts for your motorcycle, ATV or side-by-side, you should run some tests first to save yourself some money by not buying a part you probably don’t need.
We looked at how many voltage regulator rectifiers we sold over the last couple of years versus how many stators, and found about a 5:1 ratio. In other words, we sold one stator for every five regulator rectifiers. That’s a pretty solid indicator that regulator rectifiers are more often than not the problem, versus the stator.
Stator vs Regulator Rectifier
A stator is made up of windings encapsulated in resin, and the only way they’re going to break down is if they’ve been abused, shorted out or overloaded.
When there’s a charging system issue, it’s more likely going to be due to diode failure inside the voltage regulator than a problem with the stator. Regulator rectifiers are a bit more fragile than stators, so chances are the regulator in your motorcycle, ATV or UTV is going to fail long before the stator does.
Test the Wiring Harness
Before you blindly order or even test a stator or a voltage regulator rectifier, one thing you need to take into account is the wiring harness. It’s wise to get a digital multimeter and test the harness for continuity, going from the regulator rectifier wiring all the way through to the stator wiring and the connections.
Also, check each wire to ground to make sure nothing’s grounded out. After you’ve isolated the harness and you know it’s not the issue, then you can test the stator and the regulator rectifier.
Stator and Regulator Rectifier Testing
The best way to test a stator is while the engine is running. Conducting an AC test really gives you a solid picture of what’s going on inside it, because the nominal resistance is very low on these components.
It’s almost impossible for a meter to pick up the difference between a stator that has shorted out and one that’s operating correctly. Spotting an open circuit inside the coils is pretty easy. However, the majority of the time when a stator fails, it’s a short circuit, and that’s hard to pick up even with the best digital multimeters.
When testing a regulator rectifier, you can use the same digital multimeter for testing a stator to check if some of the voltage regulator’s diodes are responding in forward and reverse conditions.
To avoid buying charging system parts you don’t need, it’s worth investing in a good multimeter. That way you can test both the voltage regulator and the stator, and not end up wasting money replacing a stator that has nothing wrong with it.
The stator is always the more expensive of the two charging system components, and — as Partzilla’s powersports expert John Talley often says — nine times out of 10 the problem is going to be the regulator rectifier, not the stator.
