5 TIPS – How to use multimeter to test car battery
There are many issues that happen with cars, and many times these can related to simple things like fuses and batteries which both are easy to fix. Let’s focus in on batteries today and show you how you can do a simple test to determine if your car batter is still in working order and some simple ways you can fix try to remedy it.
Items you will need for this:
- Plastic globes (not required, but recommended)
Symptoms of a bad battery
There are many symptoms that you may see that will alert you that there are a few battery issues. These include a battery symbol on your dashboard, dim headlights/dome lights, or when starting your car you will only hear a clicking noise. When these happen, you know there will be either two reasons: a bad battery or a broken alternator.
Just as a side note, if you left your lights on when you left your car and find that your battery just got drained, that is a different situation and you will need to charge the battery up for it to start. This does not mean that your battery isn’t working.
Before I start going through the tips on testing a car battery I want to make sure to give everyone the assurance that a car battery will not shock you. Most car batteries are 12V and if you touch both the positive and negative ends of the car battery you will feel a sensation but it is not enough to harm you.
I still highly suggest to avoid touching both ends of the car battery at the same time with your hands.
Additionally, do not allow a single piece of metal to touch both sides of a car battery (as an example, a wrench) as it can cause the battery to explode or have damaging effects.
5 tips on how to test your car battery
- DC Volt/20V Setting: First and foremost, ensure you have a working multimeter that has a good battery in it. If your multimeter’s battery is low, it can throw off the results completely. But if you think it’s time to replace the old multimeter with a new one, you should definitely check Fluke 117 (see on Amazon.com) as it works great. To test a battery using a multimeter you will need to ensure you have the setting for 20V (or anything near or at the very least, 15 V) or you may only see a DC voltage setting. The range that we are looking for your Car battery to have is around 12.6 volts running through it at a given time.
- Clean the Connectors: Check the connections to ensure they are not corroded. Often you will see a brown/blue-green crystalized substance around the connection terminals. If you do see this, loosen the connectors and pull them off the battery. Then take sandpaper and clean both the terminals and the connectors. I suggest for you to wear gloves during this part as there may be some toxic substances on it. Once you’ve cleaned the terminals you can spray some WD40 onto it to ensure it doesn’t rust in the future.
- Turn on the headlights: Before you check the battery, you need to ensure you remove the surface charge on the battery. While your car is not running, turn on your headlights of the car for about 2 minutes. Once you’ve waited 2 minutes, turn off your headlights and continue to check the voltage.
- Check the voltage: Your battery will have two “leads” or terminals. These will usually be black and red. The red lead is your positive lead, and the black one is the negative lead. The negative lead is what keeps your car grounded. If there is no negative lead, you can use a solid piece of metal on your car. Take your multimeter metal prongs and connect/touch them to each of the terminals (Red to red and black to black). Just to note, if your multimeter has a min/max function it is important to set that so that you can have recorded what the highest voltage and lowest voltage was so you have both of the extremes.
- A good or bad voltage: Your goal in having a good battery is to have it around 12.6V. Once you’ve connected it to the terminals see what the voltage has. If it is below 9.4V, it’s a good sign that your battery is starting to go, but make sure you try to charge the battery up and test it a couple times before you take it in. If it’s below 5, it needs replacement. Batteries are supposed to last for 4 years and most have a warranty up to that length of time. But only about 40% of batteries sold today last until that point.
If you have a battery which requires water, you will see caps on top of the battery. When you fill this with water, make sure you don’t fill it to the top. Only fill it until you see it’s a quarter of an inch above the electrode inside it. Also make sure you use distilled/bottled water and not tap water.
In many places around the world you can also take your vehicle to different repair/maintenance shops and they will do battery testing for free. They also have more sophisticated testing tools.
Now that you know how to check the battery, you can use this knowledge to check it without paying the mechanics and using your entire lunch break. You can also use this knowledge to impress your friends. Only thing is that you need is a multimeter.
Hope you found this article helpful. If you have any questions or comments, feel free to leave them here.