Jet skis are usually all fun until you get stuck out on the lake due to a dead battery. Your thought is that you have been running hard all day and that should be charging your battery.
Typically, your jet ski does not have a high charging system like a car, but it will maintain whatever charge you have when you start. If you start the day with a weak charge, then you will have a weak charge for the next day. Batteries will need to be cared for and charged separately form the ski to keep them maintained and running as best as possible.
Do jet skis have alternators? No, jet skis do not have alternators. They have a stator which will typically maintain a charge, not fully charge your jet ski battery like a cars alternator would. The stator generates power from the rotation of the flywheel which rotates the charging coil that charges and maintains the battery.
All about Jet Ski Charging Systems
What is a stator?
The stator is a piece of static electrical equipment basically like a generator or electric motor. There is magnets that will rotate around the static stator to generate electricity to provide power to your jet ski battery and accessories.
One set of stator coils called the exciter is providing power to the spark plugs, and the other set of coils called the charging coils provides power to the charging system of the battery.
The stator is usually located behind the flywheell. To determine or get a visual check on your stator, you will need to pull the flywheel off of your motor.
Why don’t jet skis have alternators?
Jet skis do not have alternators because they do not have a belt drive system for its accessories. Compared to a car, jet skis have very little accessories to drive. You may have your electronics such as your fuel gauge, speedometer, etc, but jet skis don’t have heaters, stereos, power steering, or other items that would either be driven by a belt drive system or by an alternator supplying higher amperage.
Could you imagine a belt drive system in your ski which is getting banged around wave after wave, it would be difficult to keep reliable and going.
What is the difference between a stator and an alternator?
In a vehicle, the engine drive belt rotates a pully which rotates the alternator to make power to charge your battery and run your accessories.
Jet skis do not have belt driven accessories, and instead have a charging coil and a exciter coil which are both driven by the flywheel. The charging coil charges the battery and the exciter coil drives power to the spark plugs.
How to tell if you have a bad stator on your jet ski?
To determine if you have a bad stator which isn’t delivering enough power to charge your battery, first you will need a multimeter.
Hook both leads of the positive and negative on the multimeter to your jet ski battery. Start your jet ski. The voltage DC should read 12.8 volts or more. Give the ski a little rev and it should read up to 14.5 volts.
If your ski does not read differently when you start or rev your ski then you could have a bad magneto, rectifier, ground, or other issue directly related to your charging system.
How do I keep a charge on my jet ski if I have a stator that is going bad?
To keep your battery fully charged, we recommend charging it externally with a battery charger, or a solar battery charger to trickle power when not in use. This will keep your battery charged and not reduce it to zero if you have a temperamental stator that is not fully working.
If you do have a bad stator, you will want to fix it immediately as to not be stuck dead on the water, but the tip above will prevent you from damaging your battery in the process as lead acid batteries are not supposed to be drained under a certain percent charge.
Can you jump start a battery if your jet ski is dead on the water?
In an emergency situation, yes, you can jump start your jet ski battery. Never, and I repeat, NEVER have the vehicle that you are using to jump start be on as it could provide too much voltage and fry your electronics system. This has happened to many people and don’t cause a $1000+ dollar mistake just because you want to get riding again.
If you can use a jump start box, that is fine, just make sure you take it off right away as to not overpower your system.