A jet ski engine has many similarities to your car and truck engines, but they vary on many things.
One thing that is different with a jet ski in comparison to cars is that a jet ski uses a stator instead of an alternator.
While a stator and alternator work very similarly, they’re not completely the same and have some unique differences. In this post, I want to go over why a jet ski uses a stator instead of an alternator and the other parts of your jet ski charging system.
Does A Jet Ski Have An Alternator?
Jet skis do not have an alternator and instead use a stator for their charging system.
A stator works very similar to an alternator, both charge your battery, but a stator is more focused on maintaining the charge (“trickle charge the battery“).
A stator is mostly used on smaller engines like jet skis because they don’t take up as much room, simpler, and they can be stored inside the engine block.
Why Do Jet Skis Use A Stator?
There are 3 reasons why jet skis use a stator over an alternator.
- Stators are smaller.
- Stators can be built into the engine, which cuts down on weight and costs of manufacturing.
- Stators are simpler.
A stator is a simplified alternator that produces just enough power for small engines with batteries. Saving weight, cost, and keeping it simple is the goal with jet ski manufacturers, and thus they use stators over alternators.
Stator Vs. Alternator
What makes a stator different from an alternator is the magnets.
All generators move copper wires through a magnetic field to create electricity. A stator and alternator are no different and work the same way.
What is different is that a stator uses fixed magnets and an alternator uses electromagnets.
The alternator is creating its own magnetic fields, and doing so allows it to better control the power output of the alternator. No matter what RPMs the engine is spinning or how much power you need, the car’s alternator can adjust the magnetic field to get the power it needs.
Since the magnets on a stator are fixed and don’t change their magnetic fields, the power they produce is dependent on the engine’s RPMs. To control this power and convert the AC to DC to charge the battery, a voltage regulator (also called a voltage rectifier) is used.
Fixed magnets allow stators to be smaller and lighter, and you can put them inside the engine block. A stator just makes sense for a jet ski.
What Is A Voltage Rectifier?
A voltage rectifier or also called a voltage regulator takes the power produced by the stator and converts the AC power into DC power and smooths it out to make it more constant and predictable.
Since a jet ski uses a stator, the magnets are fixed, they can’t adjust the field, so the faster the engine goes the more electrical power the stator produces. Making too much power could fry sensitive electrical parts or even fry the battery.
Using a voltage regulator cleans up the electrical mess and makes it into something that is useful.
The voltage regulator takes a lot of abuse and do wear out over time.
One sign the voltage regulator has gone bad is that the jet ski will flash a “12-Volt Low” on the display, but this could also mean the battery is bad, grounds are dirty, or a fuse is bad.
Replacing the voltage regulator is not a hard job, it’s often next to the battery and comes off with a few screws and unplugging wires. Just make sure the battery is disconnected before you replace one.
How To Test Jet Ski Charging System?
Testing the charging system to know if the stator or voltage regulator is working fine is similar to any other small engine.
With the jet ski out of the water, here is how you test the charging system.
- Connect a volt meter to jet ski battery.
- Turn the jet ski engine on and look at the voltage reading.
- Rev the engine to 5k RPMs and look at the voltage reading.
- Turn engine off, don’t run the jet ski out of the water for no more than 30 seconds.
If the voltage reading on both is not between 13.5 and 15 volts, then the voltage regulator or stator is bad. If the voltage reading is over 15 volts at 5k RPMs, then the voltage regulator is bad.
Here is a video on how to check the stator:
Do Jet Skis Have A Magneto?
A magneto is an even simpler version of the stator, but it doesn’t charge a battery and only powers spark plugs. So a jet ski does not have a stator unless it’s a really old jet ski.
A magneto only creates enough power for the spark plugs to ignite the fuel, and often only found on engines that don’t have a battery. Things that use a magneto are push mowers and other smaller engines.
Jet skis have small engines, but they’re more complex than lawnmowers and thus need a stator.
Why Is My Jet Ski Battery Always Dead?
If your jet skis battery is not holding a charge, it could be due to the battery being bad, the stator is damaged, or the voltage regulator is bad.
If the battery is dead after sitting for months, then the battery has gone flat and lost its charge. Jet skis use lead acid batteries and if they’re not used for months they will go bad. It’s best you keep a battery charger on your jet ski if you’re not going to use it for months.
If your jet ski gives you one click when you go to start it then that is a bad starter relay as covered here.