We’ve all been there. You’re ready to hit the road but your car won’t start. Now you need to jump start your car.

Hopefully, you have kept jumper cables readily available in your car for an emergency such as this, or maybe a Good Samaritan has offered to lend theirs and their battery. Jumper cables work best when you know how to use them. True: there is a very wrong, detrimental, and costly way to apply jumper cables!

Do I have the right jump start cables? To jump a car, the diameter of the cable should be at least 16 mm. For cars with large engines, a jump start cable with a cross section of 25 mm is recommended. The vehicle which has suffered a breakdown must be supplied by a battery with the same voltage.

Our auto experts from Christian Brothers Automotive are here to walk you through how to check to see if your battery is dead and safely jumpstart it using jumper cables in 7 easy steps.

How Do I Know If My Car’s Battery Is Dead?

Car batteries die due to a variety of reasons, preventing your engine from starting, but before you dig out and untangle those car jumper cables, there’s a few things you can do to see if the problem is only a dead battery or a more serious issue you should bring to a mechanic.

To see if your car battery is truly the problem, turn the key and listen. Do you hear the engine attempting to turn over? If so, your battery isn’t the problem – take your car into a local auto repair shop for help.

However, if you don’t hear anything when you turn the key, celebrate your situation’s silver lining! Your battery has died, but it’s not as bad it as it sounds. Using a pair of jumper cables, a jump start battery pack, or a friend’s car, you should be able to get your car started.

How to Jump Start a Car Battery

Now that you’ve confirmed your car battery is dead, and you’ve wrangled the help of another car or an emergency jump-starter battery, follow these steps to get your vehicle up and running again quickly and safely. While hooking up jumper cables may seem easy, there is a specific way it must be done to avoid the risk of causing your battery to explode along with other expensive electrical damages.

How to Jump a Car

Follow these steps to jump start a car with another car:

1. Ensure both cars are turned off and that they can reach one another’s batteries with ease.
2. When jumping a car, red goes first. Connect one end of the red jumper cable to the positive terminal on your stalled car. The red cable is for a positive charge, so it’s very important to connect it correctly and always keep it connected to positive terminals. The positive terminal will be marked, so look for a + or POS.
3. If you’re using the help of a second car to start yours, connect the other end of the red/positive cable to the positive terminal on the other car’s good battery. If you’re using a jump-starter battery, be sure that the red cable is connected properly to the device.
4. Connect the black cable to the negative terminal on the good battery. If using a portable car jumper, simply check that it’s connected correctly.
5. Connect the other end of the black negative (-) cable to a clean, unpainted metal surface in the disabled car’s engine bay. The frame is a good choice, as is the engine block itself. It will serve as your ground, a critical step in preventing dangerous electric shock. Make sure the cables are clear of any moving parts.  If you connect the black cable to the negative terminal on the bad battery, you can cause an explosion.
6. Start the good car and allow it to run for two to three minutes before attempting to start the dead car. This will allow a charge to build in the dead battery.
7. After a few minutes, your car’s battery should be charged and ready to crank. Once your car cranks, safely and correctly remove the jumper cables (Yes, there’s a correct removal process; we’ll guide you on how to do this in just a moment). You should drive or let your car remain idle for at least 15 minutes before shutting it off, otherwise you may need to jump it again. Allowing it to run for a while will give your battery time to charge, so your car can start again on its own.

We cannot stress enough the proper procedure for jumping a dead battery; anything else is very dangerous. For your safety, follow these 7 Steps in order.

What Happens if My Car Battery Won’t Charge?

If jumping your car doesn’t allow your car to start up immediately, don’t continue trying the key. Instead, turn it back off, and let it charge for another few minutes. If it still won’t start after a few more tries, either your car battery needs to be replaced or something else is wrong with your car’s electrical system. If you continue to try to start your car, you may damage your ignition.

Knowing when it’s time to replace your car battery can help prevent dead batteries. Your local Christian Brothers expert auto mechanic will gladly offer some guidance on this.

How to Remove Jumper Cables?

Once your car is running, you’ll need to disconnect it. To do so, carefully remove the clamps in reverse order. Keep in mind that you’re dealing with live cables now, so it is very important to only touch the rubber covers on the clamp handles and never touch the cables together or allow them to make contact with another metal surface.

To remove the jumper cables with ease, follow these steps:

1. Remove the black ground connection from your car.
2. Remove the black cable from the ground location on the second car’s battery.
3. Remove the red cable from the second car’s positive terminal.
4. Finally, remove the red cable from the positive terminal on your car. Once removed, the cables will be safe to handle.

Turn to Christian Brothers Automotive for Dead Car Battery Services

If you find yourself stuck or stranded because of a dead battery (or for any other reason), don’t worry! Call our expert technicians at Christian Brothers Automotive to schedule a visit for a free battery check along with your own courtesy inspection. In keeping with our core value of transparency and saving you from an undesirable surprise, if your battery tests fine, any further electrical inspection will require diagnostic services. We appreciate a heads up and figure you do, too.

We offer complete auto care solutions from batteries to engine problems to electrical components and more. We can help get your car towed to our shop if it won’t start and get it running again as quickly and safely as possible, so you can get back to the people, places, and plans that matter most. For us, it’s more than keeping cars running–it’s about Driving Joy!

Find your local Christian Brothers Automotive today.

This blog was written in August 2018 and updated July 2023 to reflect current industry standards and best practices.