Posted by on 26th Nov 2019

How to Test a Battery Charger?

How to test a charger with multemeterOne of the key prerequisites to keep your rechargeable battery in good health and enjoy its long life is to make sure you charge it with a properly functioning battery charger. If you are not certain if your charging device is a top performer and reloads your batteries to a usable level, here is an easy 6-step guide on how to perform a test on a small-battery charger.

The testing procedure is similar regardless of the type of battery you’re working with. Connect the positive and negative test probes of a multimeter tool to the corresponding contact points on the charger. The device will then give you a reading displaying the voltage being put out by the charger.

1. Plug your battery charger into a wall outlet – this first step is to make sure that there’s electricity running to the charger. Hook the power cord up to a nearby AC outlet. This will cause the charger to begin channeling electricity, which you’ll measure using a multimeter tool. If your battery charger has an On/Off switch, go ahead and set it to the “On” position.

2. Attach the test probes of your multimeter to their corresponding ports (if using a multimeter with built-in test probes, you can skip this step) – Most multimeters come with a pair of detachable colored probes that are used to measure the electricity running through the poles of a battery or charger. Insert the end of the black, or negative, probe into the port on the multimeter labelled “COM.” Then, insert the red, or positive, probe into the port labelled “V”(in some cases, the test probe ports may be color-coded instead of being labeled).

3. Set the multimeter to “DCmode – Twist the dial on the face of the tool indicating the different testing modes until the pointer enters the “DC” range, stopping on the next-highest setting to the voltage of the charger you'll be measuring. Check the labels on your charger to see what the DC output is.

Important warning! Operating your multimeter on an inappropriate setting could overload it, or even result in more serious damage such as an explosion. To avoid this, always double-check that it's set for the type of current you're gauging at a voltage higher than that of your device.

4. Touch the black test probe to the negative contact point on the charger –If the charger you’re testing hooks up to a battery via a power supply cord, press the tip of the probe against the side of the metal prong at the end of the jack. If you’re testing a receptacle charger like the kind used to reload rechargeable AA batteries, hold the probe to a section of the exposed metal on the side of the charging chamber marked “-”.

5. Hold the red test probe against the charger’s positive contact point – Insert the tip of the probe into the barrel at the end of the power supply jack, which is what transmits the live current. To take a reading for a receptacle charger, hold the probe to a section of the exposed metal on the side of the charging chamber marked “+”.

6. Check the number displayed on the multimeter’s display screen – This number indicates how many volts of DC power the charger is putting out. Your battery charger needs to be supplying at least an equal voltage (preferably higher) to the batteries you’re charging in order to restore them to their full capacity in a timely fashion. If you’re not sure exactly how much, consult to the instruction booklet included with your battery charger, or look for the information somewhere on the charger itself. For reference, a standard lithium ion battery is rated for around 4 volts of electricity. Larger devices and appliances may run on batteries or battery packs that put out 12-24 volts.

If your battery charger tests well below the recommended output, it may be time to get a new one.