Buzz
As you sit in the car, you realize the engine won't start and the lights are off. After several unsuccessful attempts to start the engine, it's time to think about whether your battery might need replacing. Follow the steps below to check your car battery's condition.
Steps
Check the battery with a voltmeter
Turn off the car's ignition.
Remove the positive battery terminal cover. Inspect and clean the terminals.
Connect the positive voltmeter lead to the positive terminal of the battery. Typically, the positive lead on the voltmeter is marked in red.
Connect the negative voltmeter lead to the negative terminal of the battery.
Check the voltmeter reading. If the battery is in good condition, the voltage (the reading on the voltmeter) will be between 12.4 and 12.7 V. If the voltage is below 12.4 V, the battery needs to be recharged.
- If the voltage is below 12.2 V, a 'small charge' or slow charging process is needed. Check again once completed.
- If the voltage exceeds 12.9 V, it is too high. Turn on the car's headlights to reduce the voltage. High voltage can result from the alternator overcharging the battery.
- Even with a voltmeter available, you should still verify the battery’s charging capacity.
Check the battery using an electrical tester
Remove the positive battery terminal cover.
Connect the positive probe of the tester to the positive terminal of the battery. Typically, the positive probe is marked in red.
Connect the negative probe of the tester to the negative terminal of the battery.
Place the tester probe on the positive terminal of the battery. Read the voltage measurement.
Check the reading on the Electrical Tester. If the battery is in good condition, the voltage should be between 12.4 and 12.7 V.
Recheck the battery by starting the engine
"Start" the engine by turning the ignition key until the engine cranks, holding the key in place for 2 seconds. Ask someone to start the engine while you check the voltage.
While starting, check the reading on the Electrical Tester. It should not be lower than 9.6 V.
- A voltage reading below 9.6 V means the battery has been sulfated and can no longer hold or receive a charge.
Advice
- Most car batteries last between 4 to 5 years. In hot climates, their lifespan may be reduced to just 3 years. If charging doesn't restore the battery's charge when the car is off, it's time for a replacement.
- If purchasing a new battery, ensure proper disposal of the old battery according to local regulations. Typically, repair centers will handle this for you.
- You can check and recharge your battery at local auto repair centers.
- Before buying a new alternator, perform a thorough check of the entire system.
Warning
- Never attempt to short-circuit the battery terminals, as this can result in serious consequences such as fire, terminal damage, or the release of hydrogen gas.
Items you will need
- Voltmeter
