How to Test a Car Battery Charger With a Multimeter

How to Test a Car Battery Charger With a Multimeter

You’ve just plugged in your car battery charger and are eagerly waiting for it to bring your battery back to life. But is it working? How can you tell? Luckily, testing a car battery charger with a multimeter is a simple process. In this article, we’ll walk you through the steps on how to test a car battery charger with a multimeter. We’ll also explain how to check a battery charger, so you can be confident in the health of your battery charger.

Steps on How to Test a Car Battery Charger with a Multimeter

Stop the vehicle’s engine and open the hood.

The first step for testing a battery charger with a multimeter, is making sure the engine had stopped working. Check that the battery stays connected. If not, reconnect it and try again. Also, check that your multimeter can read a current of 12 volts from this battery before connecting it to another one in order to make sure nothing goes wrong during installation or removal of old batteries at some point in time (you may need a new cable if you cut yours).

Connect the black test lead to the negative battery terminal.

black and brown handle hand tool

Make sure you connect it to the negative terminal and not the positive one. If you are not sure which one is positive or negative, check your car’s manual or ask someone who knows what they’re doing!

Touch the red lead to the positive terminal on top of the battery.

Do not touch any part of your body or anything else, as this could damage your multimeter and/or cause serious injury or death!

Look at the screen on the multimeter a note the reading in order to determine how much voltage is being put into the battery by the alternator.

You can use a multimeter to test the voltage put into your car battery charger. The multimeter will display a reading on its screen. And you’ll want to determine how much voltage is put into the battery by the alternator. If you have an automotive-specific multimeter, it will be easier for you to do this than if you don’t have one—and if not, there are plenty of other devices available that claim they’re good for testing things like car batteries and alternators (for example).

Test for current by setting the dial on your multimeter to DC amps.

To test for current, you’ll want to set your multimeter’s dial to DC amps. This means that it will measure voltage in milliamps (or mA). You can find out how many mA are flowing through your circuit by setting the needle on your multimeter between 0 and 20 volts per meter. If there is no current flowing in either direction from terminals A or B of your battery charger, then there won’t be any volts sensed at all!

To test for this condition:

Set up a simple circuit with two resistors (R1 and R2), one connected across battery terminal A and another across terminal B; then connect them both together using an ohmmeter or voltmeter as shown below:

Use your back probes to measure three different areas with your meter to get an accurate reading

You can start with the positive connector leading out from your battery and going through your battery-to-engine cable and then moving onto your alternator and then finally touching your negative cable’s connector.

Measure the voltage on your positive charging connector. Then, measure three different areas with your meter to get an accurate reading, starting with the positive connector leading out from your battery and going through your battery-to-engine cable and then moving onto your alternator and then finally touching your negative cable’s connector.

Look at all of those readings and compare them

Since the readings should all be within plus or minus 2 amps of each other, if not then it could mean that there is too much resistance within that part of your electrical system. The multimeter will have a readout for voltage, current and resistance. If you find that these numbers are high on your multimeter (which indicates an excess amount of power loss), then there may be a problem with the charging system in your car battery charger or alternator itself.

Understanding the Metrics Displayed

The multimeter will now show two different values: voltage and current. Voltage is measured in volts, and current is measured in amps.

If you’re testing a battery charger, the voltage value should be close to or greater than the voltage rating of the battery charger. If the current value is significantly lower than the rated current of the battery charger, then it’s likely not capable of charging your battery.

How to Test a Car Battery Charger with a Multimeter – Tips and Warnings 

gray and black engine
Photo by Chad Kirchoff

Once you have your multimeter ready to go, there are a few tips and warnings to keep in mind when testing your car battery charger.

Firstly, always make sure to set the multimeter to the correct voltage setting. This will ensure that you get an accurate reading and don’t damage the multimeter or the charger.

Secondly, unplug the car battery charger before attempting to test it. This prevents any short circuits from occurring and makes sure that no power passes through the device if it is defective in any way.

Thirdly, be careful when handling wires and terminals as they easily break which could lead to a hazardous situation if not handled correctly. Always wear protective gloves when dealing with electricity for your own safety!

How to Test a Car Battery Charger with a Multimeter – Safety Gear Needed 

When testing vehicle electrical systems for faults, it is very important to make use of the proper precautions and safety equipment.

  • Safety is your number one priority. You must be able to see what you are doing and touch things without getting shocked. Always wear eye protection when working on any vehicle electrical system or other potentially hazardous equipment. A good pair of goggles will protect your eyes from flying debris while also providing clear vision in all directions, including behind your head!
  • Use good work practices when testing vehicle electrical systems:
  • Don’t work alone. Always have someone else nearby who can help in case something goes wrong (and/or if they get hurt). 2) Be sure that all power lines are disconnected before beginning any test procedures. So there is no possibility of accidentally electrocuting yourself with live wires running through the garage floorboards!
  • Wear protective clothing such as rubber gloves (changed frequently!), long sleeves/jackets (typically worn by mechanics), safety glasses with side shields covering both eyes—these items cost little money but ensure complete protection against injury while doing preventative maintenance tasks like this one! 4) Be sure there are no objects within reach which could cause severe damage upon contact with high voltages generated during faulty diagnostics activities such as these ones performed here today.

You should have the following items with you when troubleshooting a vehicle charging system:

  • A voltmeter. This can measure voltage, which is one of many ways to determine if there’s an issue with your battery or alternator.
  • Work gloves. They will protect your hands from electrical shocks and burns while working with tools that can cause them, such as a test light or wire piercing probe (WPP).
  • A 12-volt test light or WPP tested positive for safe use on DC circuits when connecting its probes/points/joints into receptacles in order to check continuity between two points on an electrical circuit board (PCB).

The safety equipment to test an automotive charging system is the same as what you need to test the engine’s ignition system or any other vehicle electrical system.

Safety is one of the most important aspects of any job, and it’s also a common practice during electrical testing. When working with high voltages and currents, it’s important that you wear protective gear at all times (including gloves).

These key items include a voltmeter, work gloves, a 12-volt test light, and a wire piercing probe (WPP).

There are a few key items that you’ll need to test the charger. These include:

  • A voltmeter. A good quality voltmeter is essential for testing battery charging systems, as it will allow you to measure voltage levels in relation to battery life and when testing other aspects of the charger, such as its ability to deliver current safely and efficiently.
  • Work gloves. It’s important that while you’re working with electronics equipment, especially if they’re high-voltage or dangerous in any way—like heavy machinery—you wear protective gloves over your hands so that no harm comes from static electricity build up from touching metal parts during testing procedures or maintenance work on electrical outlets around the home

The test light and WPP are optional

They are both very helpful tools in modern vehicles that have lots of electronic components interfering with voltage measurements.

The test light is used to check for voltage at a specific point, while the WPP can be used to test for resistance. Both tools are very useful when troubleshooting automotive electrical systems, especially those involving high-current devices like alternators or starters.

You need a voltmeter, work gloves, a 12-volt test light, and a wire piercing probe (WPP).

  • A voltmeter is used to measure the voltage of the battery terminals. If you have access to one of these instruments at your workplace, then it’s likely that this item is already in your possession. However, if not or if you don’t have one available on site at all times during testing procedures then consider purchasing one for yourself beforehand so as not to waste time looking for one later on down the line when needed most!
  • Work gloves are necessary because they protect your hands from burns while working with hot components such as batteries or wires in close proximity; however their main purpose here isn’t just safety but also protection against any potential injuries sustained during testing procedures themselves – so make sure they’re durable enough before putting them into action!

How to Test a Car Battery Charger with a Multimeter – Troubleshooting Tips 

person holding black and green electronic device

When your car battery charger isn’t working, there are a few things you can do to troubleshoot and get it back up and running. First off, if the charger is not charging your car battery properly, make sure the multimeter readings are accurate. If the voltage reading is different than what’s written on the charger, then there could be an issue with either the charger or the multimeter.

You should also check the connection points between your car battery charger and the battery. Make sure they’re clean and secure so that power can flow through properly. If you’re having difficulty, try re-reading your user manual or checking online for step-by-step instructions.

Last but not least, make sure your charger is compatible with your car battery model. Not all chargers work with all batteries, so you’ll want to double check this before troubleshooting any further.

Frequently Asked Questions:

Why is it important to test a car battery charger with a multimeter?

Testing a car battery charger with a multimeter ensures that it is functioning correctly and delivering the right voltage and current to charge your vehicle’s battery effectively and safely.

What tools do I need to test a car battery charger with a multimeter?

To test a car battery charger, you’ll need a digital multimeter, the charger you want to test, and a functioning car battery (or a suitable substitute).

How do I set up the multimeter for testing a car battery charger?

Set your multimeter to the DC voltage mode and select an appropriate voltage range. Depending on your charger, this may be 12 volts or 6 volts, as most automotive batteries fall into these categories.

What are the steps to test a car battery charger with a multimeter?

The basic steps are as follows:

  • Ensure the charger is disconnected from the electrical outlet.
  • Connect the multimeter’s black probe to the charger’s negative terminal or clip.
  • Connect the multimeter’s red probe to the charger’s positive terminal or clip.
  • Plug the charger into an electrical outlet.
  • Turn on the charger.
  • Measure the voltage output on the multimeter’s display.

What voltage should I expect to see when testing a functional car battery charger?

A functional car battery charger should output a voltage that matches the voltage of the battery it’s designed for. For most automotive applications, you should expect to see around 12.6 to 13.8 volts for a 12-volt charger.


Testing a car battery charger is a very simple process that only takes a few minutes. All you need is a multimeter, and following these simple steps will help you determine whether your battery charger is working properly or not.

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Written by webmaster_kzwort

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