How to jump start a car battery
A jump start will help bring your car back to life for a short time if the battery has failed or there’s a charging component failure. If your engine won’t spin over, the battery may be the problem. If that’s the case, a jump start can get you back on the road for long enough to get to your local AutoZone or a repair shop.
You’ll need another car and a pair of jumper cables, or a portable jump starter. This only takes a few minutes to set up, but you’ll want to carefully follow a few specific steps to stay safe. It’s always a good idea to have jumper cables and an emergency kit or battery booster in your vehicle in case you have a problem.
A note of caution: If the vehicle that will not start has an internal short or other electrical problems damage may possibly occur to the other vehicle when the jumper cables are connected.
How to jump a car battery
Before beginning ensure your clothing and jewelry do not interfere during the procedure. It’s a good idea to wear protective gloves and goggles if you can, and keep loose hair or clothing tied up. NO smoking allowed near the batteries to stay precautionary of your surroundings.
Inspect and clean your jumper cables
Make sure the connectors and wires are in good shape and rust free. Clean the clamps before attaching them to the car batteries. Even unused clamps may have gunk if they’ve been sitting in your garage or the trunk of your car for an extended period of time.
If you have a portable jump starter, it likely comes with cables. These are the ones you’ll want to inspect.
Park near your working vehicle
Park a working vehicle next to yours. Pop both hoods and secure them. Make sure the batteries are close enough for the cables to reach and not interfere with moving parts under the hood. Turn off both cars, and set the automatic gear to park. For a manual transmission vehicle, use the neutral setting. Apply the parking brake in both vehicles.
If you’re using a portable jump starter, you won’t need another vehicle. Just set the jump starter in a secure place.
Identify your cables
It’s important to connect the jumper cables to the correct battery terminals. The red connector clamp will connect to the positive battery terminal/post and the black connector clamp will connect to the negative battery terminal/post. The positive battery terminal/post is denoted by a plus (‘+’) symbol and the negative battery terminal/post is identified by a negative (‘-‘) symbol. Follow the next steps precisely to stay safe.
Connect your cables
Connect one red clamp to the positive terminal of the dead car battery. This is denoted by a circled (+).Connect the other end of the red clamp to the positive terminal of the working vehicle. Connect a black clamp to the negative terminal of the working vehicle. This is denoted by a negative (‘-‘) symbol.
To avoid ‘sparks’ close to the battery being jumped, connect the other black jumper cable clamp to a good ground on the engine such as a metal bracket. Some vehicles have a large steel or brass grounding stud that works well. This step grounds the connection.
Double check your connections
Check to make sure that all the jumper cable clamps connections are secure. You should also keep the jumper cables from twisting and in a straight line. Caution: Make sure the jumper cables will not interfere with the moving engine parts of both vehicles.
Start the engine of the working vehicle
Slightly raise the engine speed to aid in boosting the battery. Then try to start your car. If this doesn’t work, you may need to leave the working vehicle running for a couple of minutes. This will provide a new charge to the dead battery, assuming that it’s not beyond repair.
If you’re using a jump starter, this is when you would turn it on. Follow instructions to make sure you use the appropriate settings.
Try to start the dead car
Try the dead car’s starter. Make the first attempt immediately. If the dead car starts, great! Let the newly revived car run for a few minutes. Keep the (formerly) dead car running, and then turn off the jump starter or (always) live vehicle. Carefully remove the negative cable, and then the positive cable, from both cars (or just the one, if you’re using a jump starter). Once the cables are removed, drive the (newly) live car directly to AutoZone for a new battery or to a mechanic for service.
If the vehicle doesn’t start immediately, you may want to try two more times. Make the second attempt three minutes after the initial try. Make the final attempt only after 10 minutes. If your car fails to start after that long, the battery is likely completely dead. You risk damage to the starter and related components with any additional attempts. At this point, you’ll need to charge and test the battery to determine if it has completely failed.
Your local AutoZone store provides free battery charging and testing. The alternator and starter can also be tested at AutoZone. If the battery was low and tests OK after being re-charged, there may be another problem such as the alternator not charging or a slipping alternator drive belt and/or belt tensioner.
Whatever the case, AutoZone can test these components for free and provide you with Trustworthy Advice and all the right parts and tools for problem solving solutions.
By taking the steps listed here, you should be able to successfully jump-start your car. If not, then either the battery is totally dead or there’s something else wrong with the vehicle.
If the battery was the culprit and needs to be replaced, you can rely upon AutoZone to get you the battery you need and get back on the road. We also offer free battery testing, so be sure to stop by America’s #1 battery destination.
Advice, how-to guides, and car care information featured on AutoZone.com and AutoZone Advice & How-To’s are presented as helpful resources for general maintenance and automotive repairs from a general perspective only and should be used at your own risk. Information is accurate and true to the best of AutoZone’s knowledge, however, there may be omissions, errors or mistakes.
Be sure to consult your owner’s manual, a repair guide, an AutoZoner at a store near you, or a licensed, professional mechanic for vehicle-specific repair information. Refer to the service manual for specific diagnostic, repair and tool information for your particular vehicle. Always chock your wheels prior to lifting a vehicle. Always disconnect the negative battery cable before servicing an electrical application on the vehicle to protect its electrical circuits in the event that a wire is accidentally pierced or grounded. Use caution when working with automotive batteries. Sulfuric acid is caustic and can burn clothing and skin or cause blindness. Always wear gloves and safety glasses and other personal protection equipment, and work in a well-ventilated area. Should electrolyte get on your body or clothing, neutralize it immediately with a solution of baking soda and water. Do not wear ties or loose clothing when working on your vehicle.
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