You jump into your car, and you try to ignite it, but then the engine won’t start, even the headlights won’t turn on, now you realize you are having battery issues. You already know a bit about the multimeter, you might have even gotten one for yourself, but you would need to perform the test on your batteries to see if you can still make use of it, or you need a replacement.
Knowing that you can use the multimeter to check your 12-volt battery is useful knowledge, but the key question is “how do you check your 12-volt battery with the multimeter?” We have three types of tests you can carry out on your batteries and the processes involved, to assure you that your batteries and the charging systems are in good order or not.
How to Carry out the Static Battery Voltage Test
The first test we would talk about is the static battery voltage test; you should do this to know the state of charge of your battery. This test will help you decide if a little boost is all you need to get your batteries to full function.
Before this test is carried out, you should ensure that the battery has not been charged recently. For accuracy, there should be at least an hour interval between the last time your battery has been charged and the time you are conducting this test.
The next thing to do is to adjust the multimeter to a direct current of 20 volts. Then place the multimeter leads on the battery terminals in the order of positive to positive and negative to negative.
After you have done these, you won’t still know if your battery state if you don’t understand the outcome of the test, so
- When the multimeter reads 12.8 volts, then your battery should not be charged any further, because it is fully charged.
- If it reads 12.6 volts, the battery is just attaining a fully charged state.
- But when it reads 12.4 volts, the battery has attained a 75% charge level, and it could still be charged further, there would be no danger.
- A reading of 12.10 volts means that it is halfway
- With 11.90 your battery is low and in desperate need of a boost.
- 80 or lower means your battery is empty.
So that ends the static test!
How to carry out the Starting Load Test
The next test is the starting load test; it is more straightforward than the static, you would carry this out to know if your battery needs a replacement or not.
If you are taking the loading test on a motorcycle, you need to remove the seat and expose the batteries, but don’t disconnect the batteries, because you would have to start the bike.
The next step is to adjust the multimeter to a direct current of 20-volt range and connect the battery terminals positive to positive and negative to negative, while the battery is still connected with your vehicle engine, just like you did for the static battery volt test.
Now push the start button of your bike it doesn’t matter if it starts or not, just watch how the reading on your multimeter drops, those readings are what you need.
For your battery to pass a load test, the multimeter must read between 9.5 to 10.5 volts straight for 30 seconds when the battery is tested.
Any reading of voltage below 9.5 volts, or if the battery holds a good record for a while and steadily drops, or even when it falls instantly to 0 volts, then it means there is a problem, and the battery should be replaced due to its low capacity.
How to carry out the Charging System Test
This last test we would discuss is necessary to test your battery’s charging system. Just as you have done for the load test, adjust the volt range on the direct current to 20 volts, place the terminals positive to positive negative to negative, start your motorcycle.
Now bring your engine to about 3,000 RPM, then check the voltage reading on your multimeter and compare it to the specification on the owner’s manual. For a good charging system, the voltage should read between 13.8 and 14.5 volts.
You might be thinking, since all you need is a multimeter, how dangerous can it be to test a battery? But it is important to take safety precautions associated with handling lead batteries and also wear protection for your eyes.
After a load test and you discover that your battery is faulty, the problem of the damaged could be from sulphate crystal build-up, and it may be a manufacturing flaw. Bad batteries are called open-cell batteries.
We also want you to know that to avoid battery problems; you should always test your batteries and electrical system regularly, maybe twice a year, not only when it starts showing signs of weakness.
These three tests we have outlined complement each other, like situations that static battery voltage test fails because open cell batteries may read fully charged when they are idle, so the load test is necessary.