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How to Test a Jet Ski Battery With a Multimeter 

 September 19, 2021

By  Phil Borges

A lot of jet ski owners tend to compare their vehicle with a car. It is natural to do so because the car is the other big vehicle in your life whose mechanical workings you are probably most familiar with. But it is a terrible comparison because both machines are not the same.

So, if you own a jet ski, it is a good idea to get some equipment, remove the battery from the jet ski and get to know it better so that you don’t accidentally blow it. That process starts with a multimeter and here is how you use it to test the health and performance of the battery.

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Let the multimeter to DC values and at anything more than 15 volts. Most multimeters start at 20V so that’s where you’ll place it. Connect its black wire to the negative terminal of the battery and the red wire to the positive terminal. You will see the jet ski battery voltage numbers on the screen of your multimeter. It’s that simple.

But if you are going to get into the functioning of the battery, there are a couple of other things you should know, like load testing it. That is a lot more than measuring voltage and actually tells you things that you must know. Let’s jump in and find out, shall we?

How to Test Jet Ski Battery

If your jet ski is acting weird or not working the way it is meant to, you must check its voltage to make sure there are no problems with the health and functioning of the battery. And for that, you need a multimeter and must know how to use the device. If you have never done this before, you don’t have anything to worry about. Here is a quick step-by-step guide.

Step 1: Pick up the test wires and attach them to the multimeter. Typically, there are two long and insulated wires that flow out of the free terminals of the cell of the battery. In this case, you will have a red wire and a black wire. Attach the black wire to the plug which says COM. Then take the red wire and attach it to the plug that probably has a symbol like this: Ω. Basically, the red wire goes into the plug that is not marked A.

Step 2: Now, some meters have the ability to read the voltage right away because they are automatic. But if you have a device that does not have this function, you must do it manually. For that, you must select the function that has a V and two lines above it. The second line will be a broken one. This V and the two lines mean it will measure the voltage of the direct current or DC. Don’t confuse it with the V with a wave on top of it.

Step 3: You will need to select a setting. When measuring the voltage of a jet ski battery, you must set it to 20 for 12 volts which is for maximum volt reading.

Now you are ready to test the voltage of your jet ski battery. But before you do that, you must remove the covers and panels around the battery and let it air for about an hour.

Step 4: Once they have been sufficiently aired, you must turn off the isolator switches in the battery.

Step 5: Attach the red probe to the positive terminal on the battery and do the same with the black probe and the negative terminal. Now you will start to see some readings on the multimeter.

If you are trying this with a battery bank, you must attach the red and black probes the same way. Then you must disconnect every single battery individually and test it. A reading from the battery bank tells you about the capacity of the battery. It also tells you about your charging needs. 

If the reading is under 11.8 volts, your jet ski battery is completely dead. If it is somewhere near 12.2 volts, your battery is 50 percent charged. And if it is between 12.6 volts and 12.8 volts, the battery is completely charged. If you rev it up a bit, it should read about 14.5 volts. That’s how you know everything is well with the battery. This process of testing the battery is an excellent way to recognize bad batteries.

When you test the battery, if you see that the number is less than half of the voltage level of each cell, you must replace the battery. Whether you have a digital multimeter or an analog model, you can get reliable measurements. Although the digital ones are preferred and can also facilitate load testing.

But here is a small tip. You don’t always need a multimeter to know if the battery is working well. Start the jet ski and listen to the sound it makes. If you hear an effortless spin and a strong sound, the battery is just fine. But if you hear the engine sound like it is struggling, you might have a weak battery or a weak starter motor. In that case, get the multimeter out and follow the above-mentioned process.

What Is a Jet Ski Battery Tester

Now, there are two things to note here. In the market, you will find a simple battery tester but also a battery load tester. If you don’t know the difference, here is what it is.

A battery load tester actually helps you measure the performance of the battery and not just the voltage. But more on that in a minute.

How to load test a battery with a multimeter?

A good battery load tester helps to calculate the remaining power capacity of a battery. This is usually done with a two-second pulse load test. What this test accomplishes is that it simulates the same environment that would be created when a device is using drawing high levels of power from a battery.

So, when the maximum amount of power is being drained, how is the battery performing? That’s the answer you will get at the end of a load test. This is a lot more than just measuring the battery’s voltage. But you will not actually drain the battery or cause any damage to it while doing this test because the load will automatically be disconnected.

To load test battery with multimeter, you need one with a min/max button. Now let’s begin.

  1. 1
    Set the multimeter to a DC battery setting. You now know how to do this. Make sure the open-circuit voltage of the battery is more than 12.4 volts. This tells you that the battery is charged at least till 75 percent of its capacity. If it’s less than that, charge it before doing this test.
  2. 2
    Connect the black wire from the multimeter to the negative terminal of the battery and then connect the red wire to the positive terminal.
  3. 3
    Push the min/max button and start the jet ski and keep it so just for about 5 seconds. Initially, you will notice a surge in power but then it will stabilize.
  4. 4
    Switch off the jet ski engine and push the min/max button once again.

Now that the test is done, it is time to look at the results. The first reading you will see indicates the higher end of things. Typically, it will be about 14.6. Push the min/max button again and you will see the lower end of things. If it is above 9.6 volts, your battery passes the load test.

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Frequently Asked Questions

How to check a jet ski battery?

You plug in the multimeter and check its voltage. The number must be above 12 volts and somewhere near 12.2.

How to tell if jet ski battery is bad?

When you do a load test and a voltage test, if the numbers don’t match the levels we talked about in this post, you know something is wrong.

How to check 18650 battery with multimeter?

It is quite easy to check whether a 18650 battery is good or bad. You only need a multimeter and a lithium ion / Li-ion charger.

How to test a lawnmower battery without a multimeter?

Testing a lawnmower battery without using a multimeter is not difficult. The process is actually pretty simple and you can do it in your home, with the help of some household equipment.

First of all, you need to check the battery's voltage. Lawnmowers and other small engines run on 12-volt batteries. You can easily find out the voltage of your battery by using a voltmeter or multimeter. 

About the author

Hi, I'm Phil Borges.. thanks for reading.. My wife says I can't shut up about batteries so to save my marriage I've started this blog .. where I'd be ranting about batteries! Please leave a comment if you have any questions, I'm happy to help!

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