How To Use A Multimeter To Test A Car Battery
Here, we check the charge, or voltage, of your car battery. This is achieved by measuring the DC voltage of the battery in parallel with the multimeter. If you are looking to test for amperage draw testing amps in series we cover that process in this guide.
Other than trying to start the engine to see if theres charge, the best way to decipher a car batterys status is to test it using a multimeter. Digital multimeters are the best option for this since they give a more accurate reading, although you could also use an analog one. And even a cheap, category I multimeter is fine as you are merely testing voltage, not amperage.
If you dont know how to use a multimeter to test a car battery, read the procedure below:
Step 1: Set MultimeterEnsure the ignition, lights and radio are off.
Select the DC volts position on your multimeter . DC voltage is usually marked as a V followed by a short line with a dotted line beneath it. The wavy line after a V is AC voltage and is for checking the mains voltage in your house.
Most of the manual ranging meters have a 20V range, which is what you would need to test a car battery. The 20V range means it will measure between 0V and 20V. See below:
Step 2: Test BatteryWith the red lead plugged into the voltage terminal of the multimeter and the black lead plugged into the common terminal of the multimeter: position the red lead onto the positive terminal of the battery and the black lead to the negative terminal.
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As much as The Drive loves to put the “you” in do-it-yourself, we know that not everyone has the proper tools, a safe workspace, the spare time, or the confidence to tackle major automotive repairs. Sometimes, you just need quality repair work performed by professionals you can trust like our partners, the certified mechanics at Goodyear Tire & Service.
How To Charge A Dead Car Battery
Many car owners jump-start the car and let the alternator charge the battery.
While letting the alternator charge the battery works, in most cases, it is not the best method to charge a car battery and can shorten its life.
Your car’s alternator is designed to supply voltage to run your car and not charge a dead battery. Here are two reasons why you should not charge a car battery using your alternator.
If the battery is fully discharged and you jump-start the car, you risk causing an electrical problem, triggering Undervoltage fault codes on your vehicle’s control modules, and even have the car go into limp mode.
As would be when the alternator charges the battery is not healthy for the battery, a fast charge would be the case. If you want to charge your battery to 100% properly, use the slow charging method.
A trickle charger takes longer but brings the battery to a fully charged state.
To properly charge a car battery, you don’t need to remove it from the car. Even though removing or disconnecting would be the preferred method.
To determine if the battery is defective, follow the next section’s procedure to perform a battery load test.
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Allow The Car To Cool Down
The anatomy of a battery allows it to charge and discharge as it offers power to the car. With this fact in mind, it makes sense that the value measured with a multimeter will vary based on the batterys previous use.
Get a clear view of the batterys voltage by letting the car rest for at least an hour. You might park it overnight and test battery with multimeter in the morning. The resting voltage tells you if the battery is good or bad.
Cost Of A New Car Battery
When it is clear you need a new battery, then luckily there are many places you can pick up a new one. As with most parts of a car, a new battery for your vehicle comes with a range of prices and battery brands. You can pick up a brand new battery for anywhere between $50 and $150. There are also some premium batteries that may cost you as much as $300 or more. This is not necessarily something you need for your car and certainly not standard or required by any means.
It is also worth noting you can save yourself some money on your car battery by replacing it yourself rather than heading to a mechanic. A lot of people are intimidated by doing any kind of work on their vehicle but replacing the battery is one of the easiest things you can do, and its not going to take a lot of time either.
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Use The Headlight Test
This is an unscientifically imperfect way to test your battery, but it can be an easy method for checking its health.
How To Test Your Car Battery’s Charge Using A Multimeter
You can use your digital multimeter to find out in a minute whether your car battery has enough juice to get your car going.
- A reading of about 12.5 volts or higher means your battery has a good charge.
- A reading of about 12.3 volts means your battery is about 75% charged.
- A reading of 11.8 volts or lower means your battery is 25% or less charged.
If you got a low reading, slow charge your battery to improve the chemical reaction of the battery and repeat the test. If your reading doesn’t go higher, replace the battery.
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Battery Light Or Check Engine Light
Indicator lights on your dashboard can often be vague. However, when your battery is failing to hold a charge, you will likely get a warning light that pops up on your dashboard. Some cars may just throw up a check engine light first, while others will give you the battery light to let you know there is a problem. If you get these along with other symptoms, it is a good bet your battery has a problem, and you may need to replace it.
How Do You Tell If A Car Battery Has A Dead Cell
Dunedin car batteries What Are the Signs of a Dead Car Battery Cell? When the car is hesitant to start, or turn over, to get the engine moving, this is a clear indicator that one or more cells are not providing enough amperage. When the alternator is functioning, the automobile starts and operates normally.
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How To Test A Battery Using A Multimeter
Figure 1: Multimeter
Knowing how to test a battery using a multimeter is important to ensure the battery is working at optimal levels and is not showing symptoms of wearing out. A battery failure can lead to seemingly increasing problems in the hardware of an electronic system or starting troubles in a car. A multimeter can be used to check the voltage and current produced by a cell which helps to recognize a faulty battery that may be replaced. The symptoms of a poor battery and how to test a battery with a multimeter are discussed below.
To learn more on multimeters, read our . You can also learn how to in our technical article.
How Do You Know Something Is Wrong With Your Car Battery
Sometimes an imminent battery problem happens suddenly without warning, but many times there are several signs that something may be wrong with your battery before it finally dies completely. If this is the case, you can load test a car battery to see if it is good, and you can replace it before it leaves you stranded. The next question you might have is how to check if your car battery is dead. Here are a few subtle ways that your car may whisper to you that you need to check your battery soon.
- It starts slowly and cranks for some time before finally turning over
- The battery light comes on when you are going down the road
- You find traces of battery acid underneath your car where it is parked
- Your car suddenly stalls and dies as it is going down the road
- Your car lights suddenly dim, or you have dim headlights as soon as the car starts
- Your stereo, heated seats, and other electronics will not work
- Your car dies quickly after you charge it or has fast self-discharge
- Your car battery is beyond its recommended battery life.
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Battery Dead Learn How To Test A Battery With A Multimeter
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Do you know how to test a battery with a multimeter? We got you.
This article explores how you can quickly test 9-volt, 12-volt, and AA batteries with a regular multimeter.
Theres not much to it, but it helps to know a few tricks to test your batteries.
So, before getting started, well go over some things you need to know to test a battery. If you feel confident about your skills, then feel free to skip all this extra information.
What Causes Battery Failure
- Not driving often enough, or running electronics when the engine is not on, or otherwise depleting the battery.
- If your battery is consistently charged at less than 80%, acid stratification can occur. This means that the electrolyte collects at the bottom of the battery, causing the upper half to be acid-poor. Acid stratification reduces the batterys performance and may cause it to fail.
Vi: Measuring The Cold Cranking Amps Of The Battery:
In order to check the cold cranking amps of the battery, you need to throw a light load in the battery. All these need to be done when the probes are touching the terminals. Now, ask your family member or anybody to start the ignition with the multimeter being connected. Stay ready to notice the changes very quickly.
The moment you turn on the car, youll witness a sudden fall in the readings of the multimeter for a quick second. However, the readings will rise and even go up to the 14-volt mark as the alternator charges the battery. Now, ask your assistant to turn off the car and wait for the readings to settle down.
Set Up Your Multimeter
Now that youve prepared the battery, you can start setting up your digital multimeter to test your batterys voltage.
To do this, adjust it to about 20V of DC voltage. Setting it to 20V isnt a must the important thing is that its above 15V, so you get the correct reading. You can go ahead and turn your headlights off.
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What You Will Need To Follow This Tutorial
Before we get started, here are a few things that you will need to follow this tutorial.
I: Clean The Battery Case:
Open the bonnet and locate the battery there. Now, youve to follow a simple procedure to clean up the battery case. Take a cup of warm water and a little bit of baking soda. Mix them well. This basic solution will neutralize acid and easily clean up the dirt over the battery case and terminals.
Take a soft brush and dip into the solution prepared. Youve to apply the solution across the top and side of the battery case. Make sure you wear gloves and goggles to protect yourself from harmful chemicals and battery acid. If your car comes with a maintenance-type battery , protect the solution from going under the caps. Wipe the solution using a cloth if you didnt find anything getting build-up.
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Ii: Visually Inspect The Battery:
Open the hood/bonnet of your car and locate the battery. You can also check the owners manual for the same. Youve to make sure that there isnt any dirt or corrosion build-up on the terminals. This corrosion is usually a build-up of white or yellow crust around the metal. The positive terminal will have a red cover, and the negative terminal will have a black cover.
The corrosion or dust on the terminals would result in inaccurate/false voltage readings. It may be possible that corrosion itself is the reason behind the faulty battery. You can use fine-grit sandpaper or terminal brush to scrub off the coating. Dont forget to wear gloves for avoiding any contact with harmful chemicals or acid. If the terminals dont have any corrosion, youre ready to bring the multimeter into the scene.
Setting Up The Multimeter
The multimeter might look seemingly complex, but the operation is fairly easy. The DC Voltage is indicated with a solid and dashed line above the V alphabet. First of all, set the dial to 20. This allows for accurate measurement below 20 volts. Now, connect the red probe to the positive terminal and the black probe to the negative terminal. If you dont know, the red terminal is positive, and black is negative. If you are getting a negative reading, it means the connection should be reversed.
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How To Test Amps On A 12v Battery
If you want to Test AMPS on a 12v Battery, you will need:
To test the amps on your 12v battery, first set your multimeter to the amps setting. Then, touch the black multimeter lead to the negative terminal of your battery, and touch the red lead to the positive terminal. You should see a reading in amps on the multimeter display.
Now, interpreting the results can be a bit tricky. A healthy battery should have a reading of around 12 amps.
If your battery is showing a lower number, it may be starting to fail. And if the reading is zero, or very close to zero, your battery is most likely dead.
Connect The Battery Tester
- Remove the red plastic protective cover from your batterys positive terminal.
- Connect your battery testers red cable clip to the batterys positive terminal.
- Connect the black cable clip to the negative terminal, then turn on the tester.
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How To Check Car Battery Without A Multimeter
A multimeter is the best way to test your car battery to see if it needs to be replaced. It gives you a picture of how your battery is performing electronically, but there are some things that you can look for that might also tell you that your battery needs to be replaced. Here are a few of the things you should look for that tell you it is time for a new battery.
If you want to know how to check your battery visually, this video should help you out.
Things to look for are:
- Leaking battery acid
- Rotten egg smell from engine
- Extremely low water level in battery
- Cracks in the battery case
- Bulging sides on the battery case
If you see any of these signs, you should replace your car battery immediately. While it may have a little bit of life left in it, its imminent demise is near. Leaking, cracked batteries, or producing a rotten egg smell should be replaced immediately, as they are hazardous. A car battery with bulging sides is also an extremely hazardous situation, and the battery should be replaced immediately.