How to test a car battery?

Author Name – Louise Helsby

    15 people

If your car is slow to start in the morning or your battery keeps going flat, you may need to test the health of your battery.

car battery testing 

A battery test can be carried out at home with the use of a multimeter. A multimeter is an electronic instrument that measures voltage, current and resistance. To get an accurate picture of the health of your battery it is advised that it is tested when cold, preferably in the morning after the car has been left overnight.

How many volts is a healthy car battery?

A healthy battery should hold 12.6 volts as a minimum, anything less signifies that there is an issue with battery.

Car Battery Testing

The battery is commonly located under the bonnet, to the side of the engine. To test the battery, you need to ensure you have access to the two terminals on the top. Some batteries have a plastic covering which can be lifted off to expose the (+) positive terminal.

Once the battery is exposed, be careful not to rest any metal tools such as spanners etc on the terminals.

When using the multimeter, the measurement you should be interested in is the DC (direct current) voltage. The DC voltage is usually a solid line and a dashed line above the letter V.

On the multimeter, set the dial to 20 to measure 0-20 volts. Holding the red probe to the (+) positive terminal and the black probe to the (-) negative terminal the multimeter will give you a reading. If the reading displays with a minus (-) before it, the probes are connected to the wrong terminals and need swapping around.

Once correctly connected, the voltage of a rested battery should be above 12.6V. A battery that is only 50% charged would display a reading of 12.2V and a reading below 12V is discharged.

Car Batteries at National

If you find that your battery is below 12.2V this means the battery is in a state of discharge and a replacement will soon be required. Here at National we have a range of Napa batteries suitable for all types of vehicles.

We stock the following batteries:

If you’re not sure which is the right battery for your car, simply add your vehicle registration to our battery search tool or pop down to your local branch where one of our highly trained technicians will assist.

If you have any concerns about the health of your battery let our experts carry out a FREE battery test for you. Just pop into any one of our branches nationwide where one of technicians can carry out this simple health check giving you peace of mind.

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