Do Jet Skis have an alternator?
Jet skis come equipped with a charging system for their batteries, but it differs from car alternators, relying on a stator instead.
In this post, we want to go over how jet skis recharge their batteries while they run and why the systems are different from your car. Let’s dive deeper into what makes a stator unique.
The jet ski Stator explained
While stators and alternators serve similar functions by charging batteries, a stator primarily maintains the charge through a “trickle charge.”
This system works well for small engines like you find for jet skis, which are used in wet and rough environments. Interestingly, stators are lightweight, compact, and integrated into the engine unlike alternators, making them ideal for these situations.
Many jet ski engines are very similar to motorcycle engines, some are often repurposed motorcycle or snowmobile engines, so this video below going over motorcycle stators is a great one to watch and explained very well:
For those that wonder, here are the reasons a stator is used over alternators.
- Stators are smaller.
- Stators can be built into the engine, which cuts down on weight and costs of manufacturing.
- Stators are simpler.
Compared to cars, a PWC has a lot less going on, and a PWC operates in wet and rough environments, all the features above are a must.
Key Differences Between a Jet ski alternators and stators
The primary distinction between alternators and stators lies in the types of magnets and their functionality.
Common alternators use copper-coiled electromagnets, while stators depend on fixed magnets.
This setup influences power generation, especially when jet ski engine RPMs come into play. A stator’s efficiency is tied to RPMs, requiring a voltage rectifier to regulate power output.
RPM Dependent
A stator is dependent on RPMs, and the reason it’s more of a maintainer than a charger. It’s interesting to note, that do to the irregularity of power, a voltage regulator (also called a voltage rectifier), must be used.
Fixed magnets allow stators to be smaller and lighter, and you can put them inside the engine block. You won’t find alternators built in as you would with stators, well… it’s rarer.
Voltage Rectifier
A voltage rectifier takes the power produced by the stator and converts the AC (alternating current) power into DC (direct current) power and smooths it out to make it more constant and predictable for the charging system.
AC power is easier to regulate the power, and that is what both a stator and alternator generate.
Signs Of A Bad jet ski Voltage Regulator
A flashing “12-Volt Low” on the display is a common sign that the voltage regulator has gone bad. But this could also mean the batteries have gone bad, the grounds are dirty, or a fuse is bad. A bad voltage regulator can be what’s draining your batteries, and replacing it won’t fix the issue.
From what I see is that most of the electrical issues tend to be bad batteries more often than anything else.
Replacement
I consider replacing a voltage regulator as not being hard, it’s often next to the battery and comes off with a few screws and unplugging wires. (Most people could replace it with simple tools!)
Just make sure the batteries are disconnected before you replace it.
If your batteries keep going flat on you, then I got a post that covers that here.
Testing The Charging System On Your Jet Ski
Testing the charging systems and stator to determine whether the stator or voltage regulator is functioning properly is a straightforward process, similar to diagnosing other small engines. With the vessel safely out of the water, follow these steps to evaluate your stator:
- Connect a voltmeter to the battery.
- Start the engine and monitor the voltage reading.
- Rev the engine to 5,000 RPMs and observe the voltage again.
- Turn off the engine, ensuring you don’t run the PWC out of water for more than 30 seconds.
If you have voltage readings fall outside the range of 13.5 to 15 volts, either the voltage regulator or the stator is malfunctioning. Readings exceeding 15 volts at 5,000 RPMs indicate a faulty voltage regulator. While PWC batteries operate at 12 volts, higher voltages are required for charging—but excessive voltage can lead to additional problems.
If you’re having problems, the best solution is to get a new battery.
No Batteries, No Go
I’ve had a few people ask me about running without any batteries, mostly because they need a jump.
You can’t swap your batteries out and expect jet skis to run fine. The engine needs a place to dump its charge, and without it the engine will stop running.
Can you Jump Start Your jet ski Or Will You Fry The Computer?
While you can jump start your engine, it’s best you don’t.
Not many people have realized how dangerous jump-starting lead-acid batteries are, they can explode. Also, jump-starting from your car or truck is not as ideal as they output more power than the computers on a jet ski can handle, especially when they are completely flat.
You can jump start jet skis from a jump pack, like a jump starter kit, or even another lead acid battery not connected to anything. I cover more on this subject here.
Most of the time, people needing to jump start is because they left jet skis unused for months, like during the winter. It’s best you remove the batteries and charge it the night before you want to ride next season.
Consider A solar Charger
If you’re having jet ski battery problems, then it’s mostly because you’re not driving them enough.
Lead acid batteries go flat when not used for months.
If you get yourself a solar charger, it will help maintain the charge and keep the vessels ready to go on your next ride. They’re so stupid simple and effective, it makes me wonder the reason the manufacturers are not just baking them into the covers? Yamaha did this for a little bit with their Jet Boat line, but it never really took off. Do this, and you’ll easily get 3 to 5 years of life out of your batteries. A solar charger is great because you don’t take the crafts out at night, or not allowed to, as discussed here.
If you’re looking for how to charge your batteries, see the post on that here. You don’t need to charge your batteries often, only when it’s been sitting for months unused. You can overcharge them, so make sure to use a smart charger. You can use a car charger, so long as it’s 12 volts and under 2 amps, along with it being a smart charger (turns on and off as it’s needed).
This is off track from the earlier question. I have a 2003 Honda Aquatrax (sp) It’s been serviced winter and summer. Garage kept. Do have cover for it. Practically new tires on trailer. Low hours. Is it worth keeping since we don’t take it out much or should I sell it?
If it’s running fine, I would keep it until it doesn’t. Honda made some great jet skis, but certain parts will be difficult to find, but you can still do the basics like an oil change and such.