Testing Car Battery With Multimeter

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Test The Battery By Connecting The Battery Tester

Testing A Car Battery With A Multimeter-Super Easy Tutorial
  • The positive terminal of your battery has a red plastic protective cover that needs to be removed.
  • It is important to connect the red cable clip of your battery tester to the positive terminal of the battery
  • Make sure that the black cable clip is connected to the negative terminal of the tester, and then turn it on.
  • During the cranking tests that will be performed with the vehicle running, you will want to position the tester in such a way that it sits flat and would not fall down into the engine later when the cranking tests are performed. There is no need to worry about electrocution when it comes to car batteries, as their voltage is not enough to electrocute you.

V: Check The Measurements:

After touching probes with correct terminals, you need to check the display readings. If your cars battery is fully charged, you should expect your multimeter to display somewhere between 12.2 to 12.6 volts. This means that the battery is in good condition and ready to start the vehicle.

If your car battery is around 75%, the multimeter will display a reading of 12.45 volts. Any reading around 12.2 volts means the battery is 50% charged. However, if you find any figure below 12.2 volts, then your cars battery is discharged. Your battery will not work in this case. The car will start again after charging or replacing the battery. Youve to learn a simple mantra the colder the battery means, the lower the multimeter readings.

Vii: The Final Analysis:

In the previous step, we asked you to turn off the car and notice the reading. If the reading drops down to 10 volts or above, then the battery is still in good condition. However, if the reading goes below 10 volts, your battery isnt healthy and will wear off very soon. But if the reading goes down to 5 volts, you need to replace the battery with a new one.

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Put The Battery In The Garage For A Couple Of Days Then Avoid Driving

  • Before you test your car battery, wait at least a few days without driving it unless you have already determined that it would not start and suspect there may be a problem with the battery.
  • While your vehicle is running, the alternator of your vehicle charges the battery to keep the battery charged. In order to know how well your battery is holding a charge, you should test it after not driving your car for a few days. You will probably need to replace it if it runs down significantly over a period of time.
  • In order to test your vehicles battery, you will need to lift the hood, and then when you are ready if that is where the battery is located. You may find it elsewhere in the vehicle if it is not in the glove compartment.

How To Know If Your Vehicles Battery Is Bad

Testing a Car Battery With a Multimeter

The most common symptoms that come with a bad battery and will include:

  • Low battery level on your vehicle dashboard display
  • Headlights may not turn on and will be dim and can’t sustain running for even two minutes
  • The vehicle engine clicking when you turn your car on
  • Delayed ignition
  • Often needing frequent jump starts
  • Interior lights may turn on, but the car won’t start.

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How To Check The Voltage Across A Car Battery Using A Multimeter

A car battery is usually located in the engine compartment towards one side of the engine, but can also be placed under the wheel well, the back end of the car, or even in the trunk. Refer to the owners manual in case of any confusion regarding the battery location. Also, access the battery terminals by looking for metal connections on the top or front of the battery. Perform the following steps sequentially to check the voltage across the car battery when the car is off:

  • Turn on the headlights for 2-3 minutes to eliminate any surface charge on the battery.
  • Turn off the lights.
  • Set the multimeter dial to 15-20V .
  • Connect the plug of the red probe to the VmA port of the multimeter and the black probe to the COM port.
  • Connect the multimeter leads to the batterys terminals .
  • Take the reading on the multimeter.
  • If the car is off, a reading of 12.2 V-12.6 V shows that the battery is in good condition and fully charged, and if the measured voltage is less than 12.2 V, the battery is weak and may have to be replaced.

    When the vehicle is turned on, the battery drives the starter motor, so more power is drawn from the battery. The voltage rating drops for a moment as soon as the car is turned on, but it shouldn’t get below 10 V. If the measured voltage is below 10 V, the battery may not have sufficient turnover strength and may be prone to failure soon, hence may be either recharged or replaced.

    How To Check Battery Amperage Using A Multimeter

    In most cases, the voltage across a battery can be measured to check if a battery is working or dead. But if the goal is to ensure whether the battery can supply sufficient current to a load, make sure to measure the amperage of the battery in milliampere-hour . Batteries are rated in amp-hours and voltage. Check the batterys label to determine the voltage and amp-hours of the battery. For example, 12V 95Ah means the battery provides 12V at 95 Amperes for an hour.

    Perform the following steps to measure the amperage in a battery:

  • Disconnect the battery from the circuit.
  • Rotate the multimeter dial and set it to measure DC of the appropriate current range .
  • Connect the plug of the red probe to the VmA port of the multimeter and the black probe to the COM port.
  • Connect the multimeter leads to the batterys terminals .
  • Take the reading on the multimeter.
  • If the multimeter reads somewhere around the value given on the batterys label, the battery works fine. For example, if a battery designed for 100mAh gives a reading of 98.5 mA on the multimeter, the battery works fine.
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    How To Test Cold Cranking Amps Of A Car Battery With Multimeter

    We will attach the probes of a multimeter with the car battery properly and this time we are going to start ignition.Battery voltage shouldn’t drop below 10 volts, if drops below 10 volts, then we have a battery problem.We had observed that voltage dropped down about 10 volts and then it popped back up at 14 volts. That’s because the alternator is charging the battery. So, we had checked out battery has enough cranking amps and is in good condition.If your battery starting to go below 5 volts, your battery’s garbage, you need to buy a new one.We hope this article will help you how to test voltage or electric current of a simple AA cell or the car battery.

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    How to Test a Car Battery with a Multimeter

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    Ii: Clean The Battery Terminals:

    Similar to step I, its time to remove dirt or corrosion away from the battery terminals. Youve to use the same baking soda and warm water solution for cleaning both the terminals. You can also pour the solution into a foam cup and dip the terminals for about 2 minutes.

    After doing this, take a battery-post cleaning tool and remove the corrosion from the terminals. Keep repeating this step until you find your cars battery free of corrosion.

    How To Check A Car Battery With A Multimeter

    The first test with your multimeter will measure DC voltage, indicated with a solid line and a dashed line above a letter V. Set the dial to 20, which will allow you to accurately measure between 0-20 Volts.

    Touch the red probe to the positive terminal, and the black probe to the negative terminal. The terminals will be marked + and -. If you get a reading with a minus in front of it you’ve got the probes the wrong way round!

    The resting voltage should ideally be no lower than 12.6V. A battery that reads 12.2V is actually only 50% charged, and is classed as discharged below 12V.

    One thing to bear in mind is that all modern cars experience ‘parasitic loss’, which is when something electrical drains the battery even with the engine turned off. So, systems such as the clock, computer and alarm use some power. If you suspect this is killing your battery during storage, you might be wise to disconnect the battery or remove it entirely.

    If the multimeter reads less than 12.6 volts, disconnect the battery and fully charge it using a battery charger. Then let it rest overnight. If it holds a charge when it’s not connected to the car something is draining the battery far faster than the computer memory and digital clock.

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    Find Your Cars Battery

    To test your cars’ batteries, you should know where your battery is located, with most vehicles having their battery under the hood in the engine bay and on one side of the engine. However, modern cars may have batteries in their trunk and if you can’t find your battery, consult your mechanic or the car’s manufacturer’s website to determine the location.

    Today’s vehicles have a plastic cover covering their batteries, and you may need to unscrew the cover to access the battery’s terminals. Avoid anything metal such as tools from touching your terminals as they may shorten it.

    Is A Car Battery Tester Worth It

    Electronic Automotive Relay Tester for LED 12V Cars Auto Battery ...

    It depends on what you need it for. If you just want to test your battery to see if its still good, a car battery tester is probably not worth the money. However, if youre having trouble starting your car and think your battery might be the problem, a car battery tester can be a valuable tool in diagnosing the issue.

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    Reveal The Batterys Terminals

    Knowing how to test a battery includes the understanding of the terminals. Every car battery has positive and negative terminals. Once connected to the car, electrical current flows between the terminals as the battery activates the ignition system.

    • Locate the terminals under plastic or rubber covers. Some vehicles have screwed-on caps as alternative protection.
    • Carefully remove the covers. Keep any metal objects, such as hand tools, away from the terminals. They can shock you. You can keep the wires connected to the terminals as you test car battery with multimeter.

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    First Off What Is A Multimeter

    Testing your car battery with a multimeter is the easiest and most effective way to get the job done. We are assuming you will NOT have one handy but for the record, a multimeter is an instrument designed to measure electric current, voltage, and usually resistance, typically over several ranges of value.

    However, if you do not have a multimeter handy there are a couple of things you can do to test a car battery.

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    Testing Batteries With A Multimeter

    Before you learn how to test a car battery, there are a couple of things to keep in mind. A multimeter itself is going to test one thing on the battery, and thats to measure voltage. A battery test at AutoZone has an advantage in that its going to simulate a starting load on a battery. Many bad batteries will appear to have full voltage, but when it comes to holding that voltage under load, the battery reveals it is bad. There are several things you can do at home to simulate a load, which we will walk through, but none is as good as a thorough load test that AutoZone can perform.

    Next, you should only test a battery after its been sitting unused for at least an hour. This is known as resting voltage. If you test it immediately after use, you can receive a false reading from a unit charged by your cars electrical system, also called a surface charge. Once youre sure you can use your multimeter, youre ready to get started.

    How To Check Car Battery Without A Multimeter

    How to Test a Car Battery with 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.

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    Bring The Battery In To Autozone

    Its important to note, that jump-starting and driving on a potentially bad battery is not a good practice. A bad battery that cannot keep a charge puts an incredible strain on an alternator, which is not designed to put a high-amperage charge on a battery, unlike generators of old, which could do this. This is one of the prime reasons why many vehicle owners change out their battery, only to come back where they purchased the battery a few days later, angry that the battery has died again, only to then find out the worse news the alternator is also bad. If you suspect the battery is bad based on your multimeter testing, remove the battery and bring it into AutoZone for further testing. If the vehicle will start on its own, bring it into AutoZone where it can be checked. If you do end up replacing the battery, you can learnhow to test your charging system here, or bring the vehicle back up to AutoZone for a charging system test. Dont assume once the battery is changed that everything has returned back to normal.

    How To Visually Inspect The Battery Case And Cables

    Now its time to check the physical condition of your battery case. A damaged battery case can not only prevent the battery from working properly, but will eventually kill it. To check the battery, youll need to remove it from your vehicle.

  • First, disconnect the battery cables starting with the ground terminal and then the positive terminal. Now, unscrew the hold-down mechanism to remove the battery from the tray.
  • Make sure the hold-down mechanism works. If theres missing hardware, replace it. This hardware prevents the battery from bouncing and getting damaged when the vehicle is moving.
  • Place the battery on a workbench or similar surface. Carefully examine the battery case for potential damage. Check for a bulging side or cover, cracks around the case, or damaged terminal posts. If your battery is damaged in any way, replace it.
  • Overcharging and internal short circuits will cause a battery to swell as the acid turns to gas. So if you find signs of bulging, check the charging system as well.
  • Now, check the battery cables. Check for frayed, cracked, or worn insulation around the cables and the condition of the cable threads. Replace them as necessary.
  • Make sure the hold-down mechanism on your battery is working.

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    Checking The State Of Charge Of The Battery

    Batteries come in all shapes and sizes, and each has its own particular way of indicating how much charge remains. While some batteries have an indicator on the outside, others have a tiny light that glows when the battery is charging.

    Knowing how to check the state of charge on your battery can help you save time and money. As a general rule, most batteries should have a charge state of at least 80%. The 12V battery in your vehicle should be able to jump-start another car if necessary. If the battery is completely dead, its unlikely that any amount of charging will be effective.

    Troubleshooting Other Causes You Should Check

    Digital Multimeter with Battery Tester eM530S

    If the battery is not reading the proper voltage with the multimeter, the first thing you should check is whether there is corrosion on the posts. If there is, you can disconnect the battery cable ends and terminals with sandpaper or a wire brush. Reconnect the battery cables, always starting with the positive cable first and retesting the battery, starting with step 3 on this list. Please make sure the cables are tight enough and cant be pulled off of the posts easily by hand.

    Before testing your battery, make sure everything is off, including the radio, lights, and any other electronics that could pull energy from the battery. You also want to see if you have a device that is drawing electricity from the battery even when it is supposed off, called a parasitic draw. This video explains how to do this test with a multimeter.

    This process will help you diagnose your battery problems and help you narrow down whether it is your battery or something else.

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