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How To Test Battery Charger With A Multimeter: Explained!

When new batteries that you bought a few months ago don’t seem to work, it gets confusing. Have the batteries already gone bad or is there something wrong with the charger, you start wondering. Don’t worry, we got you covered.

How to test a battery charger?

Put a battery in the charger and plug it into an outlet. Attach probes to a multimeter. Touch the negative side of the charger with the black probe and the positive side of the charger with the red probe. If the multimeter displays the volts equal to the capacity of the battery, the charger is fine.

If you are interested to read more about this topic, we have a detailed segment on it. We will be discussing the multimeter and how to check the charger in step-by-step order in the following parts. Stick with me till the end.

Check If Your Battery Charger Is Alright

If you work with rechargeable batteries all the time, you may have a battery charger at your home as well. Batteries get old and eventually die. But when a new battery stops working, we start wondering if the battery charger is okay or not.

Nothing much to worry about though. Checking battery chargers is very easy with a multimeter. Just match the reading of the meter with the batteries.

Apart from battery chargers, a multimeter can check amp, voltage, and other electric measurements. It can be used to test circuit breakers and engine ignition coils as well. But for this article, we will focus just on battery chargers.

Things You Would Need

To check if a battery charger is alright or not, you will need some electrical instruments. You would require:

  • A battery / a pack of batteries
  • A working power outlet
  • A battery charger
  • A multimeter
  • Probe wires

Step 1: Remove the Batteries and Power On

The first step to check a battery charger will be to remove all the batteries from it. Give the charger a quick cleaning and go to a power outlet to plug the charger in. Choose an outlet that is not hard to plug in.

Power on the battery charger and ensure there’s electricity flow in that. You can check that with the multimeter as well or use a tester screwdriver.

Step 2: Prepare the Multimeter

Grab a multimeter. It should give you the volt measurements once you start giving it input. Find the probe wires and plug them into the multimeter to get started. Put the meter on DCV mode.

The probes consist of two colored wires. The hot one or positive one is painted as red and the idle one or negative one is painted as black. These probes touch the electric source and give a reading on delivered volts.

Step 3: Attach the Black Probe to the Negative (-) Contact Point

The black probe test wire resembles a negative point and should be met with the negative contact of the battery charger. If it is a AA battery charger, then the negative side will have a metal prong.

For other kinds of battery chargers, find the minus (-) marked the negative end and attach the test probe to that contact point.

Step 4: Attach the Red Probe to the Positive (+) Contact Point

The black probe test wire denotes the positive point of the multimeter and must be connected with the positive contact of the battery charger. For AA battery chargers, it has to be on the opposite side of the metal prong.

While checking chargers other than AA type, find the plus (+) marked the positive end and connect the test probe to its contact point.

Step 5: Check the Reading and Match

When the multimeter probes are connected to the contact points of the charger, check the display of the meter. It should have a reading of negative or positive charge in volts.

If the reading of volts from the multimeter matches the volts of the batteries that are supposed to be charged by that particular charger, it’s fine. Otherwise, there are some problems with the battery charger and you should fix or replace it.

For example, AAA, AA batteries have a capacity of 1.5 volts. So, a charger that is built for charging these batteries should output 1.5 volts and a multimeter will read that. If the output from the battery charger is lower than 1.5 volts, it has issues.

Here are some of our recommended battery chargers that you can check out:

Product 1
Product 2

How Does Multimeter Work?

A multimeter is one of the most widely used electrical tools. Almost every electrician on earth owns a multimeter. It is called a multimeter because it can give readings of many electrical properties. It’s like an all-in-one tool.

It usually has two probes or needles. The probes are color-coated. Black means negative or idle end, Red means positive or hot end. Digital multimeter also features a digital display, while analog meter has a pointer that swings between positives and negatives.

It can measure grounding, the current, voltage as well as resistance. It can be used to check circuits, batteries, motors, home wiring, power supply, and many more electrical commodities.


Question: How do I know if the battery charger is broken?

Answer: You can’t directly identify if your charger has gone bad or not by looking at it. You need to run a test on it using a multimeter to be sure. 

Question: How to check a battery charger amp output?

Answer: Usually, this information is written on the charger body, packaging, or manual it comes with. But you can always check such information using a multimeter.

Question: How do I know if my battery charger is working?

Answer: If the charger is recharging batteries fine, there is nothing to worry about. But if it isn’t then change the batteries first. If that fixes the issue then your charger is fine.


With that, we have reached the end. We hope your battery chargers are okay or you now understand how to test battery charger. If you still can’t figure out how to check your charger, then take it to a technician, he can help you with that.

Hope you have enjoyed our segment for today. Leave us feedback if you wish.