One of the most common household applications of a multimeter is battery testing.
The easiest way to check whether a battery, say an AA piece that you use in a TV remote control, is in good condition or not is to connect it to a multimeter’s test probes and measure its voltage or amperage.
If you have been wondering how to test a battery with a multimeter, then this guide will walk you through it.
We will use a pocket digital multimeter and a 9-volt battery for this guide.
For more information about measuring other quantities such as resistance or capacitance, check out our other articles.
How to Test a Battery with a Multimeter?
The basic idea is to check if a battery is capable of supplying enough amperage to a load.
In our case, let’s assume the load is a TV remote control (RC). For a nine-volt battery, we will check both the voltage as well as the current.
How to Check Battery Voltage Using a Multimeter
Set up a multimeter in a table along with the battery to be tested. We will use a 9-volt radio battery for this guide.
#1 - In Part 1, we will measure the voltage of the battery. To do this, use the switch dial to select DC voltage measurement. Since battery generates DC power, we will measure DC voltage.
#2 - We already know that the voltage of the battery is 9V maximum, so we will point the dial to 20V (as shown) i.e. the higher range
#3 - Connect the test probes – black with negative, red with positive – to the battery and check the display
#4 - The display should read a value that is just short of 9V. Since this battery has been in use for some time, it shows 8.74V, which is still enough for it to supply current to the load.
#5 - For another (drained) battery, the reading looks like this
In most cases, this voltage measurement of a battery is enough to understand that it’s working properly.
However, to ensure that it can supply enough current to a load, let’s also measure the amperage in milliampere-hour (mAh).
How to Measure Battery Amps with A Multimeter
In Part 2, we will measure the current of the battery.
#1 - Select the DC current function using the dial and keep it at 200mA since we know that the amperage of the battery will be around 100mAh.
#2 - Connect the test probes similarly as you did for voltage measurement and check the display.
It should fluctuate around 98.3, which denotes that the amperage is 100mA – enough to run the small PCB of the TV remote control
It should be evident that testing a battery using a multimeter is one of its easiest applications.
So, whenever your TV or air conditioner remote control starts behaving funny, you can quickly take out your multimeter and start getting some answers.
Note
- Even if the battery shows a good reading, there can still be an issue while it is attached to a load.
- There are certain multimeters available in the market that simulate a load to test the battery. These multimeters can be a great addition to your toolkit.
While diagnosing, if a battery has a voltage level that is half of its original rating, it might be a good idea to get a new one. This is because batteries drain out faster once they reach the midpoint.
You can also use a simple voltmeter or an analog multimeter to check batteries. Instead of digital display, these meters will give you an accurate, direct reading on the scale.
How to Use A Multimeter To Test A Car Battery
A multimeter can also be used to test heavy-duty car batteries or alternators that may be giving you problems such as dim headlights or delayed ignition.
Even though you can check the health of your battery through the dashboard display, sometimes the battery charge can fully drain, leaving you no choice but to open the bonnet. That is where our humble multimeter comes into the picture.
The process is similar to what we did above, where you connect the test probes to the terminals of the battery and check the reading.
Battery ratings change from car to car, but a good ballpark would be 15V to 20V DC. In our case, we will select the 20V range as shown.
Tip – It is a good idea to switch on your headlights for a few minutes before checking the battery. This will wade off any surface charge that it may have.
In the image above, the reading is 12.78V, which is a good value for a one-year-old battery.
If the measured value is more than the minimum value (around 12V) then it is certain that the battery has a good charge.
However, this measurement alone is not enough to understand whether it is in good condition or not. You still need to check if your car can successfully draw power.
And the easiest way to check that is to test the cold cranking amps (CCA) that trigger the ignition. Most batteries are assumed to be good for a period of 3-4 years.
How To Test The Cold Cranking Amps (CCA) of a Car Battery
- Keep the multimeter probes connected to the battery terminals and fire up your ignition.
- You will need an extra hand for this specific task because you need to check how the reading fluctuates while you crank up the ignition.
- In an ideal scenario, the value should drop (around 10V) and return to a higher value (more than 12V).
- And if the reading stays constant while the engine is still running, you can confirm that the battery is in spick and span condition.
In the above image, the reading is 14.73, which is also a good number for the cold cranking amps value.
If the initial reading is around 5V, then your battery is working but is about to go bad. If it is way below 5V, then it is time to replace it.
Conclusion
Testing a battery whether a car battery or AA batteries, as you see, is very easy and quick. The key is to try it out with different batteries that might be lying around (in your house or lab) to understand different charge positions.
We hope this guide has been helpful on how to test a battery with a multimeter. If you have any questions, let us know in the comments.
Bruce Rivers
