Last Update: 10 Jan 2021

How to Test a Car Battery With a Multimeter?

James Kelly
James Kelly

Hi! This is James. I'm a professional writer and working on this field for a long time. Basically I love to write about everything related to tools, diy and home improvement. All my writings speak for itself as I'm passionate about this. I love to explore new things as well as new places whenever I get free time. You'll never find me free for this reason!

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If you are a vehicle owner, then it is a must for you to know how to test a car battery with a multimeter.

In the market, you may find many car batteries that do not need any periodic maintenance. But you can’t expect them to last forever.

For that reason, knowing the checking process of your car battery is required.

You can either use a multimeter or use a hydrometer.

In this article, we will only mention the testing instruction using a multimeter.

At 80°F, while the headlights are on, your multimeter should give you a reading of around 12.6 volts between the two terminals. For further information, read below thoroughly.

How Can You Know if Your Car Battery is in Poor Condition?

To know if your battery is in bad condition, you have to check your battery for some common symptoms.

Approximate Volts Your Car Battery Should Have

A typical car battery should have approximately 12.6 volts.

However, as the car battery discharges, it is required to set the battery for at least one hour before testing the battery. It is called “resting voltage.” It gives the accurate results of the health of your car battery.

It will be perfect if you leave your car overnight, and then in the morning, test your car battery before starting it.

If your car’s charging system works decently, and recently you have a long drive. Your car is more likely to provide higher results than the resting voltage.

Methods To Check Your Car Battery

You can choose between two methods of checking your car battery. One is using a multimeter, and another is using a hydrometer.

The first method refers to a digital multimeter by which you can check whether your car battery has sufficient charge to start your car. This method is beneficial for maintenance-free batteries or batteries with no removable caps. In some maintenance-free batteries, you may notice there is a charge indicator. When your car is fully charged, a green dot will be visible. And when the battery needs a charge, no color will be visible. If your battery is faulty, then a yellow dot will be visible.

The second method refers to using a hydrometer. By using a multimeter, you can only check the charge condition. But, by using a hydrometer, you can also know its overall health as well as its charge condition. However, you can only use a hydrometer to check non-maintenance-free batteries or batteries with removable caps.

In this article, we will only discuss using a multimeter to check your car battery.

Step by Step Procedure on How to Test a Car Battery With a Multimeter

If you have a reading of around 12.6 volts, then you have adequate battery health. However, your car battery may be holding a charge but doesn’t have the cold-cranking amps to start your car. To check the cold-cranking amps, do the following steps,

This time reading should not drop below ten. If your reading is below ten, then your car may have a battery problem. And if the reading does not drop below ten, then your car battery has adequate amps, and the cells are in the best condition.

Below five, your battery is a total loss, and you must replace it right away.

Testing Your Car Battery Terminals by a Multimeter

In some particular conditions, your car battery terminals become faulty, not your battery itself. You may face problems starting your car if battery terminals are corroded, dirty, or loose.

However, there is good news for you. You can easily test your battery terminals for a voltage drop, which indicates your battery connections condition. The procedure is given below,

If your multimeter shows a reading more than 0.5 volts, there is a possibility of a corroded or dirty positive battery terminal.

If the voltage reading is higher than 0.5, you have a problem with your negative battery terminal.

Checking Battery Alternator Using a Multimeter

Alternator refers to a component that helps your car battery to recharge while the engine is operating.

This component can also turn the engine’s mechanical energy into electrical energy and provide this power to different electrical units of your car.

The reading must be between 13.8 volts and 14.4 volts. Below 13.8 indicates your battery is undercharging and above 14.4 indicates your battery is overcharging.

Both of the conditions can lessen the endurance of your car battery. You may need help from a mechanic or an automotive electrician to fix your car’s electrical mechanism.

Final Verdict

Checking your car battery is relatively easy if you are well-informed about the proper process.

A multimeter is an important device to use in different kinds of electronic workshops. Testing a car battery health condition is one of the main tasks of multimeters.

In the above, we’ve informed you regarding how to test a car battery with a multimeter. We believe this instruction was significant to you.

If you have any further questions, please write them in the comment section below. We will get back to you soon.

A Proper Instruction on How to Test a Car Battery With a Multimeter 1