How to test your car battery
Is your car battery losing strength, and you're considering testing it? Several factors can cause a decline in your battery's performance.
While long drives generally provide enough time to recharge the battery, the battery's voltage naturally decreases with age. Factors like frequent short trips, extended periods of inactivity, and using electrical functions while the vehicle is stationary can accelerate this decline.
If your starter motor is struggling to turn over and the engine doesn't start quickly, it's often a sign that your battery doesn't have enough charge. This issue is especially common during cold weather when low temperatures reduce battery capacity.
How to Check the Battery's Charge Level Without a Measuring Device
A simple method to check your car battery's charge is by using the low beam headlights. With the engine off, park your car facing a wall, turn off the engine, and switch on the low beams.
If the lights dim rapidly, this is a sign that your battery may be undercharged.
Testing the Car Battery with a Multimeter
For a more precise test, use a multimeter, a device that measures the battery’s voltage.
There are different types of multimeters—ranging from professional models to more compact options. Ensure you select one that’s appropriate for your battery's voltage. Set the multimeter to direct current (DC) and choose the correct voltage range.
To perform the test, connect the red cable to the positive terminal and the black cable to the negative terminal. The multimeter will display the battery’s voltage.
The most important value is the resting voltage, which should be checked after the battery has been idle for at least an hour.
Compare the measured voltage with a reference chart to assess the state of charge. Keep in mind that AGM batteries tend to have higher resting voltages.
- If the battery's resting voltage is below 12.4 volts, it's advisable to charge the battery by taking a long drive or using a charger.
- If the voltage remains below 12 volts, it may be time to replace the battery to avoid starting issues. Be sure to follow your vehicle manufacturer's guidelines when selecting a new battery.