Knowing how to test battery chargers, whether used in small electronic devices or used in vehicles, is very helpful in making sure they are capable of delivering sufficient charge to the battery. The battery charger test procedure is generally the same for all battery types. Connect the positive and negative ends of the multimeter to the corresponding points of contact on the charger. The device will display the power voltage supplied by the battery charger.
Step
Method 1 of 2: Performing a Test on a Small Battery Charger
Step 1. Plug the charger into a power source
To find out if the battery charger is supplying the appropriate voltage, you'll need to make sure there's electricity flowing to it. Plug the power cord into the nearest power source. This will allow electricity to flow to the charger so that the voltage can be measured using a multimeter.
- If the charger being tested has an On/Off button, make sure the switch is in the “On” position.
- A multimeter, sometimes referred to as a “voltmeter”, is a type of device designed to test the voltage across a variety of electronic devices. You can buy a digital multimeter at a material store or electronics supply store for around IDR 100,000 to IDR 200,000.
Step 2. Connect the tip of the multimeter to the appropriate port
Most multimeters are equipped with colored wires, one black wire and one red wire, to measure the electrical power flowing at each pole of the charger. Insert the black lead (negative lead) into the port labeled “COM” on the multimeter. After that, insert the red tip (positive end) into the port labeled “V”.
- Sometimes, the port for inserting the cable uses a color instead of a label, depending on the model of the device you are using.
- If the multimeter comes with a built-in test cable, you can skip this step.
Step 3. Set the multimeter to “DC”
Look for the mode dial on the front of the tool which shows several test modes. Turn the regulator until the tip is pointing to the words "DC" and is right at the highest voltage number on the charger you want to test. This method will make the multimeter able to do the test, namely by measuring the current "DC" aka "direct current" (direct electric current).
- To test a standard 1.5 volt AA battery, you must use the “2 DCV” setting.
- “Direct current” means that electricity flows directly from the device that produces it to another device that receives it.
Warning:
Operating the multimeter with incorrect settings can cause overload or even cause serious damage such as a small explosion. To prevent this, double-check the settings to make sure you are using the appropriate mode for the type of current being measured and using a higher voltage than the device power.
Step 4. Touch the end of the black wire to the negative contact point of the charger
If the charger being tested is connected to the battery via the power supply cable, press the end of the cable against the metal plate on the side of the cable end. If you are testing a charger that is plugged into a wall outlet such as an AA battery charger, hold the end of the cable against the metal plate that is on one of the poles of the charger marked “-“.
Some multimeters have input ports that allow you to connect several types of power supply cables directly to the device
Step 5. Hold the end of the red wire at the positive contact point on the charger
Insert the end of the cable into the barrel at the end of the power supply cable that conducts electricity. To read the current on a charger that is connected to a wall outlet, stick the end of the cable to the metal plate on the side of one of the poles of the charger marked “+”.
If you accidentally plug the test lead upside down, the multimeter may display a negative current reading (or no reading at all). Swap the wires at each pole and try again
Step 6. Check the number shown on the display of the multimeter
This number indicates the total voltage of the direct current supplied by the charger. Your battery charger should provide at least the same (preferably higher) charge as the battery under test to periodically restore its maximum current capacity.
- If you are unsure of the required voltage, consult the manual that came in the box with the charger or look for the information directly on the charger.
- For reference, standard lithium ion batteries have a capacity of about 4 volts. Larger appliances and furniture may be powered by a set of batteries rated at 12 to 24 volts.
- If the battery charger draws a lower current than the minimum recommended current, we recommend purchasing a new appliance.
Method 2 of 2: Testing Car Battery Chargeability
Step 1. Turn on the car battery
Once the battery is on, turn on the headlights to “activate” the battery and reduce the build-up of residual current on the surface of the battery. However, do not start the car engine just yet. Before testing the charging capability of the battery, you should measure the “static reading” to check the current charge level of the battery.
- If you want, you can also turn on the car's radio, fans, emergency lights, and other electrical components to activate the battery more strongly.
- Eliminating current build-up in the battery will ensure that you get an accurate reading according to the charging capability of the alternator.
Step 2. Set the multimeter to “DC” mode
Turn the dial that controls the test mode on the multimeter so you can measure direct current at a higher voltage than your car battery. Just like batteries in small devices, car batteries rely on direct electric current to power motors, headlights, fans, and other electrical components.
Car batteries usually emit a current of 12 volts or about 6 times more than ordinary batteries. To prevent overloading the multimeter, make sure you set it to a higher voltage than your battery (usually 20 DCV)
Step 3. Connect the multimeter test lead to the car battery terminal
The best way to do this is to insert the end of the cable vertically into the space between the terminal and the metal plate around it. This way, you can ensure that the cable doesn't come loose on its own during the test. Position the negative cable first, then adjust the position of the positive cable.
After attaching both wires, the multimeter should show a reading close to 12.6 volts. This is the static battery voltage indicating that the battery is carrying an electric current, not indicating that the battery is charging normally
Tip:
Attaching an alligator clip to the end of the test lead may be helpful if you are having trouble keeping it attached to the battery terminals.
Step 4. Start the car engine
The number that appears on the multimeter will decrease rapidly as the starter draws power from the battery to start the engine. Leave the engine running for about 5 minutes so the alternator can charge the battery a little.
If your headlights or other electrical components dim or turn off momentarily when you start the engine, this may be a sign that your battery is faulty
Step 5. Turn off the car and make sure the reading is 13, 2 or higher
Turn off the car engine by turning the key, also turn off the lights, radio, and other electrical components. When the engine is turned off, the multimeter will issue a new reading. If the result is higher than the battery static voltage, it indicates that the alternator is functioning properly and is able to charge the battery properly.
- If there is no change in the readings, your car's alternator may be faulty. Consider taking your car to a repair shop so it can be repaired by a professional.
- Look for readings within the same voltage range when you were testing an external battery charger.
