Reasons Why Your Jet Ski Battery Dies

Do you ever feel like you have to replace your jet ski battery every year?

It can be quite puzzling why your battery in your Sea-Doo, Yamaha, or even Kawasaki keeps dying and needs to be replaced often.

Let me show you why your battery keeps dying and what you can do about it.

Signs of a Bad Battery

How you know you have a dead battery is when you put your key on and all your jet ski does is click multiple times. This is not to be confused with one click you get from a bad starter relay.

Also, a battery could be so bad that the watercraft doesn’t even turn over or barely does anything. Some watercraft will even say “12 volt low” to let you know the battery is weak.

Does the Jet Ski Have a Charging System?

I often get asked if riding around for a bit will charge your battery on your jet ski. This works for cars but not for jet ski engines.

Your jet ski does have a charging system but it uses a stator instead of an alternator as found in cars. A stator does not fully charge your battery but instead maintains a charge.

So riding your jet ski will not fully charge it, it will put a slight charge back but when you go to leave the watercraft for a few hours the battery will be dead again.

Can I Jump My Battery on My Jet Ski?

Do NOT jump your battery on your jet ski from your car battery.

This will overcharge the system and fry the electronics on your jet ski.

Let me say this one more time since it happens too often, DO NOT JUMP START YOUR JET SKI BATTERY!!!

Why Does My Battery Go Dead?

You only have to replace your battery in your car every few years, so why can’t your jet ski battery last longer?

The reason why your car battery lasts longer is that you drive it all the time and your jet ski is only ridden parts of the year.

When a battery just sits it goes bad by sulfating. Sulfating is when the plates on the battery build up and cause it to lose charge over time. The same thing would happen to your car if you only drove it a couple of times a year, but happens faster for a jet ski because its battery is smaller.

How to Make Your Jet Ski Battery Last Longer?

The best way to keep your jet ski battery lasting for years is to keep it on charge when you’re not using it.

There are two ways to do this…

How Long Does a Jet Ski Battery Last? – A good jet ski battery can last 3 to 5 years as long as you keep it charged when you’re not using it and keep it away from the extreme cold. If you don’t keep your jet ski battery on charge when you’re not using it or go months without riding your jet ski then you can expect it to last a year.

I recommend a 5-watt solar panel or maybe even a 2.5 watt and just hang it off the jet ski when you’re not using the jet ski. What the solar panel does is keeps the battery alive by smacking it with just enough power to keep it from sulfating.

Smart Battery Chargers will come on when it starts to lose power and will cycle until you take it off. I prefer the solar panel option because it is as simple as pulling the panel out of the storage compartment and hanging it off the watercraft. The solar panel doesn’t need a wall outlet and just works.

What if I Can’t Charge My Battery?

You’ll need to charge your battery if it’s dead. You could also disconnect the negative cable to keep any excess power draw from happening but this is merely a band-aid on the problem.

Also, the wise tell about how you can’t put a battery on concrete is false as long as you keep a battery charger on it. It’s best to keep the battery in a warm place too. Keeping the battery somewhere cold is not good either.

If your battery is too far gone then it will be time for a new one.

Click here to read my post about the best batteries to use and how to install a battery into a Seadoo.

Winter Battery Storage

It’s best to get your battery out or keep it on charge during the winter.

I’ve seen many people go out to their watercraft when the winter is over and try to get it ready for the summer. They try to start the machine but the engine won’t start because the battery is dead.

They’ll call up whoever winterized their jet ski and complain that they didn’t do it right and want the problem fixed.

If you did not keep your battery charged with a battery charger or solar panel then there is a good chance your battery will be dead by the time warm weather comes around. The cold and the lack of being charged kills the battery quickly and often it can’t come back to life from it.

Also, if it’s been about 3 years or more then it might be time for a new battery. I would wait till spring before I put a new battery into the machine.

Jet Ski Battery Won’t Stay Charged

If you find that your jet ski battery won’t stay charged then it’s a good chance something is draining it or the stator has stopped charging.

To check to see if the stator is bad you need to take the jet ski out of the water and turn it on for a few seconds and test the voltage of the battery. The battery should be pushing close to 14-volts, if it’s not or hovers at or below 12 volts then something is wrong with the charging system.

Other things that will keep a battery from charging…

  • Bad Rectifier
  • Bad Grounds
  • Sulfated Battery Plates from sitting too long or improper charging
  • Bad Computer
  • Wrong size battery
  • Damage or corroded battery cables
  • Blow Fuse
  • Broken Gauge
  • Broken Key
  • Leaving the Key on when you’re not using it(happens often)
  • Broken battery charger or not using a smart battery charger.
  • Overcharging the battery. You want to stay under 2amps when charging a jet ski battery and use a smart charger so it doesn’t overcharge when the battery is full.

43 thoughts on “Reasons Why Your Jet Ski Battery Dies”

  1. My Jet Ski is telling me I have low voltage, I took the battery out and did a load test and it seemed fine, charged it, ran good for one ride, next time I got a low voltage. I put a meter on it while running and the voltage slowly went down. Put the battery in my other jet ski and the voltage went up and held at 13.5 volts. It sounds like my charging system is not working, checked the fuses.


Leave a Comment