Testing car battery with a voltmeter

If you want to test your car battery you really just need a voltmeter.

The general rule is if the voltage is below 12 Volt when your car is not running your battery is weak.It should be above 13Volt.


The second check to do is to monitor the voltage of the battery when you start the car.If the voltage drop between 9.5V 11V the battery is weak if It drop below 9.5V you need to change your battery or desulfate recondition it.

The third check to do is when your car is running check the voltage again and it should be above 13.5 Volt which is what is coming out of your alternator.
This will make sure your alternator regulator is OK.

The best way to extend your battery life is to keep it fully charged at all time.
If you have a car that you don't often use disconnect the battery from the car and use a battery charger to keep it full.

Battery can die suddenly weather condition can affect the battery.

Mechanic those days use jump starter (portable battery pack) more convenient to use than cables hooked to another car.

Some Automotive Multimeter multi function tester allow you to send voltage to a relay that controls whether or not a fan switches on. You can quickly test the voltage and polarity of a circuit or whether it's short or open, check continuity, locate cylinders which are misfiring, measure frequency of ignition pulses, test solenoids, lights and more. To top it all off the easy to read LCD is backlit so it's perfect for the dark services of an engine bay.