Is Your Car Battery Dead? How to Tell

Without a strong battery, your car doesn't have the power it needs to start. If you leave this problem unchecked, you might even get stranded in unsafe locations far from home. Here's how to tell if your car battery is dead and what to do about it.

Check Your Lights

Look at the light knob in your car. Is it switched to the off position? If not, you may have accidentally drained your battery by leaving the lights on. In this case, calling roadside assistance to get someone to come out to jump your dead car battery is a good option.

If you know you didn't leave your lights on, try to turn them on. If they aren't working, your battery may be dead, but it could be something else. A car with working headlights that won't start may have a mechanical issue or a non-functional starter. 

Check Your Battery Cables

If your car starts sometimes and is inexplicably dead sometimes, you may have battery terminals that are broken, loose, calcified, or corroded. You can open the hood and look at your battery cables to check for a white buildup or leaking fluid right away. If the cables are look frayed, are wiggly, or are falling apart, you may need to have a mechanic replace them. 

Pay Attention to the First Time You Crank Your Engine Each Day

Cold-cranking refers to the amount of energy your car needs to get started for the first time each day. Your battery provides a certain number of cold-cranking amps so your car has the power to start after the engine has been off for a while. If your engine seems to struggle to turn over the first time you turn the key each day, you may have a weak battery.

"Common symptoms associated with a bad battery include slower than normal engine cranking or an engine that doesn't crank at all," said Mia Bevacqua, Chief Mechanic at "If the engine cranks normally but doesn't start, the issue is likely an engine performance problem, (e.g., fuel delivery or spark delivery), rather than a dead battery. Having a professional test your battery is the best way to determine whether it’s bad."

What to Do if You Think You Have a Dead Battery

If your car won't start when you turn the key, a dead car battery may be a problem. You could have a faulty starter or alternator, but most of the time, jumping the car and/or replacing the battery should fix the problem.

Ideally, you'll have quick and easy access to another running vehicle and a quality set of jumper cables. Follow the instructions included in your vehicle's owner's manual to jump your car. Be sure to let it run for at least 15 minutes so your battery can recharge.

Jumping your car may not completely solve your problem. Don't risk getting stranded. If you have an old or weak battery, you may need to replace it. You can usually have your battery tested at an auto parts store or battery store. Unless you want to go through the process of jumping your car again in the near future, replace an old or weak car battery right away.

Understanding the basics of how your car battery works and looking out for signs that you have a weak battery could prevent you from being stranded because your car won't start. Of course, a dead battery isn't the only thing you'll encounter behind the wheel. When you take a state-approved and certified driver's ed course, you'll learn about other common car issues and how to deal with them.