Your car battery powers the engine and essential electronics, making it the heart of the system.
Thanks to modern technology, maintaining today’s car batteries is much easier than it used to be. Most lead-acid batteries on the market are now Sealed Maintenance-Free (SMF), often using Enhanced Flooded Battery (EFB) technology.
Modern lead-acid batteries no longer require tasks like topping up with distilled water or adding acid.
That said, some simple maintenance tasks still help extend battery life.
For example, you can use a multimeter to check your battery’s voltage and assess its health.
So, how important is it to check your car battery’s health with a multimeter?
The short answer is very.
So, how do you use a multimeter?
How To Use A Multimeter
If you’ve never used a multimeter, it might seem intimidating, but once you understand the basics, it’s simple.
Usually, your multimeter will have a few parts, which include:
- A display to show your readings.
- Dial or selector knob that allows you to choose what you want to measure (voltage, current, resistance, etc.).
- And two probes, which are red (positive) and black (negative/ground).
There are three ports, which can be confusing, but the port labelled COM (common) always has the black probe plugged into it.
The other two ports are VΩmA and 10A/20A. Which port you use depends on what you’re testing.
Plug the red probe into the VΩmA port when you want to measure low to moderate current (mA), voltage (V), and resistance (Ω). These are usually the most common measurements you’ll look for when using a multimeter.
For those unsure of what these measurements mean:
- Measuring V is to check the electrical potential across a component or battery.
- Testing Ω is to check if a wire, resistor, or component works as it should.
- And measuring the mA is to check if small currents are moving where they should.
If you’re measuring high current (above 200mA), move the red probe to the 10A or 20A port.
There are a few common uses for a multimeter.
Common Function and How to Use It
There are four main functions you can use a multimeter for, which include:
- Measure Direct Current (DC) Voltage
- Measure Alternating Current (AC) Voltage
- Check Continuity
- And measure resistance Ω
When checking your battery’s health, you will want to measure the direct current.
Set the Right Settings
To measure DC voltage, you will want to ensure that the red probe is in the VΩmA outlet.
Depending on your multimeter, you should set it to DCV or V⎓, and select 20V (or the closest setting above 15V) for 12V batteries. Selecting the closest range means more accurate readings.
Once the multimeter is set, you’re ready to test the battery.
Turn Off the Engine
Before measuring the battery, make sure that the engine is turned off. Also, ensure that all accessories such as the lights, the radio or the air conditioner are turned off.
It’s advisable to allow the battery to rest for at least 30 minutes after driving the vehicle to ensure that you’re measuring a resting voltage.
Connection Time
To measure your battery’s voltage, you must use probes to touch the terminals.
Use the red probe to measure the positive terminal labelled with a +, and the black probe on the negative terminal labelled (-). While the terminals are colour-coded for most automotive manufacturers to align with the multimeter, some will swap them around.
Always look for the terminal label rather than their colours.
If there is some dirt or corrosion, make sure to clean it off with a cloth.
Interpreting the Reading
If everything has gone according to plan, you will want to check what the multimeter displays. Generally, these are what the readings mean:
- 6V or higher – Battery is fully charged
- 4–12.6V – Healthy, partially charged
- 2–12.4V – Low charge, consider recharging
- Below 12.2V – Weak battery; may need replacement soon
- Below 11.8V – Battery is likely failing.
You can perform a crank test for those who have someone to assist them with performing the readings.
Your car’s battery sends a large jolt of volts to the engine’s starter motor to turn over the engine.
Simply have them turn on the engine while you have the multimeter’s probes on the correct terminal.
A healthy battery should stay above 9.6V while cranking, while a drop below 9.6V indicates a weak battery or internal resistance issues.
When testing your car’s battery, be cautious not to touch both probes together while connected.
If the battery is swollen, corroded, or leaking, replace it immediately.
Should you have any other questions or need to replace your car’s battery, you can visit one of our stockists or a SABAT Xpress.