How To Test a Car Battery

Reader Question


Ok, just went out to my car and the battery is obviously dead. What caused it to die without any notice is another question for you, but for now how can I test the battery myself and see if I just need a new battery or if there is another problem that needs to be addressed?




Hi Diana, good question


The VERY simple rule of thumb, or at least MY rule of thumb regarding dead batteries is this. If the battery terminal connectors are all corroded and full of that blue/green/white ish powder around the battery cables….clean them FIRST. You might just have a bad connection at the cables connecting to the battery.

Next simple rule of thumb tip, if the battery is 3-4 years old now…its probably already at it’s useful life span and should be replaced anyway.

I would say 8 out of 10 times it’s just a bad battery OR a battery connection corrosion problem.  A bad alternator that has failed to recharge the battery is not as common as it once was.

Here is a pretty simple video showing you how to test a car battery with a voltmeter you can buy at any auto parts or Home depot store.

This is a much more professional approach to my rule of thumb, but even our top mechanics will just “eye ball” a customer dead battery and say ” I need a new battery”, then they will test the rest of the charging system with the voltmeter and attempt to re-charge and test the customer battery.

The average life of a car battery is about 3 1/2 to 4 years.

About the Author:

Austin Davis, consumer car repair advocate. "Hi there! I love to help people solve their car repair problems and I hope my site was helpful to you today. Thank you for stopping by."