June 25


Do jet skis have Alternators ?

By Steve

June 25, 2022

If you are a big fan of tracking across water, jet skis offer a fun and practical way of doing so. The problem comes in when you are suddenly stuck in the middle of the waterway due to a dead battery. What most people tend to assume is that since they have been running hard in the water for some time, then the battery should have been charging all this time.

Jet skis do not have alternators. Instead, they have alternative charging systems that consist of a fixed stator that has a spinning flywheel around it. While stators are also involved in electricity generation, they cannot charge the battery like what vehicle alternators do. What they do is help in maintaining the charge of your jet ski’s battery.

Unlike cars, jet skis have a low charging system but at the same time maintain whatever charge is left in the battery. This means that if you start your jet ski on a weak charge, this is the same charge that will be maintained going into the next day. To better understand why jet skis do not have alternators and what type of charging system they use, read more.

Why Jet Skis don’t Have Alternators

One of the reasons why jet skis have a different charging system and not alternators is because they have fewer electronic components compared to vehicles. There are no features such as power steering, lights and other features that consume electricity in jet skis.

Electric consumption is still relatively lower in jet skis with a large LCD dashboard and a braking system since these features do not require much electricity. For this reason, a car battery has a higher amperage of 48 amps compared to that of a jet ski that ranges from 12 amps to 30 amps.

What is a stator on a Jet Ski ?

A jet ski’s charging system has two main components, a stator and a flywheel. So what exactly is a stator? The stator can be described as the main static part of the charging system. It comprises a number of electromagnetic coils that generate electricity for your jet ski. The power generated is supposed to:

  • Feed the ignition system
  • Charge the battery

A jet ski stator takes the appearance of an airplane’s engine only this time, in miniature size. The bunches of small electromagnetic coils in the stator are divided into two sets. One of the sets is known as the exciter and its role is to generate electricity for the spark plugs. The other group known as the charging coils charges the battery.

How is Electricity Generated in the Stator ?

The key to electricity generation in the stator is the flywheel. Within the entire charging system, the flywheel is a spinning metal wheel that stores rotational energy. Since the flywheel features a metallic rim that is full of magnets, it is these magnets that generate electricity as the flywheel rotates around the stator. The whole process converts mechanical energy into electrical energy.

The Difference Between a Stator and an Alternator ?

There are a number of technical terms that might confuse you when looking at the difference between an alternator and a jet ski charging system. In a nutshell, some of these terms touch on whether the stator in a jet ski is a generator and the key features that differentiate alternators from stators.

Some technical terms that describe the difference between alternators and a jet ski charging system include:

  • Stator: This is the static component in a jet ski’s charging system that generates electricity. Electricity generation in a stator occurs as the flywheel rotates around it.
  • Flywheel: The flywheel is also part of the jet ski’s charging system and features a metallic wheel full of magnets that rotates around the stator.
  • Generator: A generator refers to many things. In the context of vehicles, a generator is any device that generates electricity. A generator operates the same way that an electric motor does only this time, in reverse direction where instead of being fed electricity to rotate, it produces electricity during its rotation.
  • Alternator: Alternators are very similar to generators as both perform a similar function. However, both alternators and generators work very differently.

So what is the difference between alternators and a jet ski’s charging system?  In vehicles, it is the engine drive belt that enables the alternator to rotate and subsequently charge your car battery. In jet skis however, there are no belt-driven parts.

Instead, it is the flywheel that drives the charging and exciter coil with the former charging the battery and the latter powering up the spark plugs. A vehicle alternator and a jet ski’s charging system convert mechanical energy into electrical energy.

The major difference is in the design where jet skis charging systems have a spinning electromagnetic field as a result of the flywheel rotating around the stator. In an alternator however, the electromagnetic field spins inside the stator itself and not around it.

This difference is what makes alternators more powerful hence the ability to fully charge your battery. Jet skis charging systems on the other hand are less powerful and can only maintain your battery’s charge.

What is a Rectifier Used for in a Jet Ski ?

The entire Jet Ski’s charging system has four main components, the battery, the stator, flywheel and the rectifier. So what is the role of the rectifier in a jet ski? The rectifier converts AC (alternating current) to DC (direct current).

The reason for this conversion is because the stator generates AC (alternating current). This current needs to be converted to DC (direct current) to make it appropriate for the jet ski’s electrical system.

How to Test a Jet Ski Stator

If for instance you suspect that the charging system has an issue, the problem is probably in the stator. As it is with most electrical parts, stators are susceptible to breaking down. For example, a stator will break down from corrosion as a result of water leaking inside the hull.

So how is testing done on a Jet Ski stator? Start by conducting a static and a dynamic output test using a multimeter. This is done by hooking the positive and negative ends of your multimeter to your jet ski’s battery.

Once you start the jet ski, the DC voltage should be at least 12.8V. If you rev up your jet ski, this voltage should go up to 14.5V. A different reading when starting the jet ski is a sign that there is a malfunction either with the magneto, rectifier ground or other related issues with the charging system.

Beyond such visual checks, you can do a further inspection of the stator but this will require you to remove the cover of the flywheel. For regular maintenance checks of the stator, it is recommended that you read the owner’s manual.

How to Maintain a Jet Ski’s Battery Charge if the Stator has malfunctioned ?

There are ways that you can keep your battery charged even with a bad stator. It is recommended that you charge the battery externally or install the jet ski with a solar battery that stores power when the jet ski is not in use. This means that even with a non-functioning stator, your battery charge will remain constant if not fully charged.

This however does not imply that you are no longer required to replace your jet ski stator. Charging the battery externally or using a solar battery is only supposed to ensure that your battery is not damaged considering that the charge of lead batteries is not supposed to go below a certain point.

When are you Allowed to Jumpstart Your Jet Ski ?

In emergency situations, you are allowed to jumpstart your jet ski but with some conditions. One of the conditions is that if you are using your vehicle to jumpstart the jet ski’s battery, then the car should not be on. With the car on, the voltage from the car might be too high for your jet ski such  that it might end up frying the entire jet ski’s electronic system.

This common mistake continues to happen to many jet ski owners and ends up costing them thousands of dollars in repairs just so that they can ride again. In case you are using a jump start box, make sure that you do everything the right way so that you don’t end up overpowering the jet ski’s system.

Final Thoughts

Jet skis tend to operate as if they have an alternator since most of their features require a charging system but in reality, they don’t. By not having an alternator, jet skis charging systems generate less power that is only enough to maintain the battery’s current charge. For this reason, it is recommended that you constantly check your battery before riding your jet ski.

If you have a weak battery, recharge it so that you are at a lower risk of getting stuck while out in the water. NEVER jumpstart your jet ski with your car on or use the conventional jump packs wrongly. Doing this can easily destroy your jet ski or even end up destroying some of your car’s electronic parts.

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